How many uplights do I need for an oak tree?

A wide canopy often needs more than one lighting direction. Kichler prefers two 35° accents over one 60° flood for medium deciduous trees. One narrow uplight may light the trunk and leave the canopy dark.

Why is my tree dark at the top?

Usually the beam is too wide, too close, or aimed at the trunk — not a lack of watts. Use photometry for throw, then aim at night. If the crown stays dark, choose a narrower beam or another direction before more wattage.

How wide is a 15° beam vs a 60° beam at 20 ft?

A Projekt Supply geometric estimate: about 5.27 ft wide at 15° versus about 23.09 ft at 60°, same 20 ft distance. That is not manufacturer photometry.

Landscape lighting design

How to Uplight Trees

Palm Trees vs Oaks: Fixture Count, Beam Angle, Placement & Brightness

Written by Projekt Supply Lighting Team. Last reviewed September 4, 2026. First published September 3, 2026. Application guidance in this article is sourced to manufacturer and authority publications. Catalog examples are checked against Projekt Supply's current public Dabmar records. Numeric beam diameters are Projekt Supply geometric calculations, not manufacturer photometry.

Palm vs oak: start with tree form

A palm is a vertical trunk with a crown. An oak is a trunk plus branching, layered canopy architecture. Palm: put the light where it can travel up the tree. Oak: put the lights where they can open into the tree.

Night view of a tall palm uplit along the trunk beside a spreading oak lit from two sides into the canopy. — Palm vs oak form

Palm vs oak / wide-canopy starting comparison. Typical / often / starting point — not a code requirement.
Characteristic	Palm	Oak / wide canopy
Tree form	Vertical trunk / column with a crown.	Trunk plus branching, layered canopy architecture.
Typical fixture count	Often one fixture from a single primary view; a walk-around specimen typically needs more sides.	Often more than one lighting direction. One narrow uplight may light the trunk and leave canopy mass dark.
Typical beam strategy	Starting point: narrower beams that can travel up the trunk into the crown.	Starting point: medium or wider beams that can open into limbs and canopy, often overlapping.
Typical placement	Often closer to the trunk so the beam can graze bark and stay concentrated vertically.	Often farther from the trunk so the beam can open into scaffold limbs before it is blocked.
Primary aiming goal	Graze the trunk and carry light into the crown.	Light trunk structure, major limbs, and canopy mass.
Common mistake	A wide flood on a tall, thin palm that brightens the lower trunk and never reaches the crown.	A single close-in uplight that sketches the trunk and leaves the canopy a dark silhouette.
Best suited fixture style	Adjustable directional spotlight when aiming into the crown matters; a well light when hardware must disappear.	Adjustable directional fixtures for overlapping canopy shots; well lights where turf or foot traffic hides hardware.
When multiple fixtures help	Thick trunks, multiple viewing sides, or a crown that still looks flat after one well-aimed narrow beam.	House-plus-street views, wide spread, or when one beam cannot cover both trunk architecture and canopy mass.

Tree uplighting starting points

Starts for a slim one-view palm: 1 fixture, 10–15°, 1–3 ft from the trunk. Pick photometry for throw, then aim at night. If the crown is dark, use a narrower beam or another direction before more watts.

Tree uplighting starting points. Compact starts only — sourcing is under the table.
Situation	Fixtures	Beam start	Distance start	If the crown stays dark
Slim palm / one primary view	1	10–15°	1–3 ft	Narrower beam or another direction first
Feature palm / walk-around	2 sides	10–15°	1–3 ft each side	Narrower beam or another direction first
Thick date or Sylvester-type palm	2	10–15°	Farther than a slim palm	Narrower beam or another direction first
Fan palm / Bismarck-type form	1–2	35°	Far enough to open into the fan	Narrower beam or another direction first
Small ornamental shade tree	1, or 2 if two views	35°	Close enough to graze trunk into canopy	Narrower beam or another direction first
Typical mature oak (~30 ft class)	2	35° (not one 60°)	Farther than a palm	Narrower beam or another direction first
Wide / heritage-scale oak	1 trunk + 2–3 canopy	15° trunk; 35° or 60° canopy	Trunk nearer; canopy farther out	Narrower beam or another direction first

10–15°, 35°, and 60° are Kichler application numbers for trunks/columns and deciduous trees — not a claim that every manufacturer uses the same labels.
Palm 1–3 ft setbacks and treating a palm as a column plus crown are Projekt Supply design starting examples, informed by Kichler’s graze-the-trunk and trunk/column notes. Kichler does not publish a palm-specific fixture count.
Kichler prefers two 35° accents over one 60° for medium deciduous trees. The 15° + 35°/60° layered method is Kichler’s large-tree (60–100 ft) approach, used here as a starting idea for heritage spread.
The “if the crown stays dark” column is a field method, not a lumens-per-foot rule. No manufacturer source in this research set states 50–100 lumens per foot of height as a requirement.

Manufacturer: Kichler Lighting Manufacturer: Kichler Lighting

How many lights do I need to uplight a palm tree?

Count the sides people actually see first, then the tree form. A slim palm against a wall, viewed mostly from a patio, may need fewer fixtures than a specimen in a circular drive.

Three night views of the same oak: one front uplight with a dark far side, two opposite uplights, and four uplights around the tree. — Viewing sides

One-view: a tree read mainly from a patio or one window often starts with one well-aimed uplight.
Two-view: house plus street, or two seating areas, often needs a second lighting direction.
Walk-around / 360°: a lawn or drive that circles the tree typically needs coverage on more than one side so the dark side does not become the composition.

Kichler: most small deciduous trees only need one accent, but if viewed from two angles the tree may benefit from two; more viewing angles may require more accent lights. Manufacturer: Kichler Lighting Connect that to form: a palm is still a column. Extra fixtures are for extra sides or trunk mass, not a required 2–3 count.

How many lights do I need for an oak or wide-canopy tree?

A wide canopy usually needs more than one lighting direction because one narrow uplight may illuminate the trunk but leave the canopy dark. That is a common starting arrangement, not a rule that 2–3 fixtures are always required.

Trunk shot: graze bark and the first branching so the structure reads.
Main scaffold limbs: aim into the architecture of the tree, not only the bark cylinder.
Canopy mass: overlapping medium or wider beams often fill volume that a single close-in spot cannot.

Kichler prefers two 35° accents over one 60° for medium deciduous trees, and layers a 15° base shot with additional 35° or 60° canopy fixtures on large trees. Manufacturer: Kichler Lighting A typical 30 ft oak is not automatically a 60–100 ft Kichler large-tree job; use the medium analog first and add directions if house-plus-street views still leave canopy mass dark.

What beam angle should I use for a palm vs an oak?

A narrow beam concentrates the same light into a smaller area. A wider beam spreads it over a larger area. Narrow beams can appear more intense at distance; wide beams can better fill broad canopy mass.

Manufacturers do not all define narrow, medium, and wide identically. Kichler’s application numbers are 10–15° for a trunk or column, 35° for many deciduous trees, and 60° for wide canopies. Manufacturer: Kichler Lighting As approximate orientation bands for this guide — not an industry standard — narrow is about 10–25°, medium about 25–40°, and wide about 40–60°+.

Kichler also notes that a beam opens with distance, and that a narrow beam hitting a thick low branch may stop there. Manufacturer: Kichler Lighting Tall thin trees need narrower spread; wide canopies need wider coverage or more fixtures.

15° vs 35° vs 60° at the same distance

Geometric cones at 10 ft. Numeric diameters are in the table under the drawing. This is not manufacturer photometry.

Approximate geometric beam diameter at 10 feet
Beam	Approx. diameter at 10 ft
15° narrow	2.63 ft
35° medium	6.31 ft
60° wide	11.55 ft

How wide is a beam at 20 ft?

At 20 ft, using diameter ≈ 2 × distance × tan(beam angle / 2), a 15° beam is about 5.27 ft wide and a 60° beam is about 23.09 ft wide. Same throw, more than four times the width. That is a Projekt Supply geometric estimate, not manufacturer photometry. Projekt Supply geometric calculation

Approximate geometric beam diameter at 5, 10, 20, and 30 ft. Not manufacturer photometry.
Distance	15°	25°	35°	60°
5 ft	1.32 ft	2.22 ft	3.15 ft	5.77 ft
10 ft	2.63 ft	4.43 ft	6.31 ft	11.55 ft
20 ft	5.27 ft	8.87 ft	12.61 ft	23.09 ft
30 ft	7.90 ft	13.30 ft	18.92 ft	34.64 ft

FX Luminaire’s RS 35° uplight publishes a photometric beam-width table (for example about 7.9 ft wide at 15 ft on the LED20WFL listing). Our 35° geometric estimate at 15 ft is about 9.46 ft. The difference is expected: manufacturer tables use measured intensity, not tan(θ/2) on the advertised angle. Manufacturer: FX Luminaire

How far from the trunk should the fixture sit?

Placement changes where the beam opens. There is no universal setback. Small trees, large trees, narrow beams, wide beams, viewing direction, roots, irrigation, mowing, and maintenance all affect where the fixture can sit.

A landscape spotlight close to a palm trunk sending a narrow warm beam up the bark into the frond crown at night. — Palm placement starting idea

Palms: closer placement can graze the trunk and keep a concentrated vertical shot. Kichler tells designers not to be afraid to graze the trunk on the way to the canopy. Manufacturer: Kichler Lighting

Two landscape spotlights farther from an oak trunk, with overlapping warm beams opening into the limbs and canopy at night. — Oak placement starting idea

Oaks: moving the fixture farther out can allow the beam to open into major branches and canopy. Kichler places large-tree canopy accents away from the trunk pointing into the canopy, and places fir uplights farther from the base. Manufacturer: Kichler Lighting

Why does my tree look bright at the bottom and dark at the top?

The lower trunk is close to the fixture, so it receives a smaller, hotter part of the beam. The crown is farther away, so intensity falls and a wide beam may already be too dilute — or blocked — before it arrives. Watts alone do not explain this.

Beam too wide for the height and form
Fixture too close, so the cone opens below the crown
Not enough candela for the throw distance
Beam aimed into the trunk instead of the crown
Canopy or low limbs blocking a lower-positioned shot
Insufficient fixture count / missing viewing side
Ambient light reducing contrast at the top

How many lumens or watts do I need for tree uplighting?

For a tall tree, beam intensity and distribution can matter as much as raw lumen output. Do not make wattage the primary brightness specification.

Watts: Electrical load. VOLT: add fixture wattage to size a transformer; watts are energy consumed. Manufacturer: VOLT Lighting
Lumens: Total emitted light. DOE: lumens measure light output; watts measure energy use. Kichler: lumens are the way brightness is expressed, formerly discussed as wattage. Authority / independent: U.S. Department of Energy
Candela: Intensity in a direction. NIST: the candela is the SI unit of luminous intensity. Authority / independent: NIST
Footcandles / lux: Light arriving on a surface. Manufacturer photometric tables report this at distance; we are not calculating exact footcandles without those files.

Same lumens, different tree

Two fixtures can both produce 600 lumens. One with a narrow beam may deliver much more intensity onto a distant crown than one with a 60° flood, because the same flux is concentrated into a smaller solid angle. That is a conceptual comparison, not a photometric study. We are not fabricating candela for Dabmar models; those records do not list lumens or candela in the public catalog used here.

A real manufacturer example: FX Luminaire lists the RS LED20WFL at 250 delivered lumens, 35°, and 570 center-beam candlepower — intensity and lumens are published together, not watts as a proxy for throw. Manufacturer: FX Luminaire

If the tree lights are on a low-voltage landscape run, size load and cable before adding fixtures. How to size a landscape transformer

Long 12-volt runs also see voltage drop. Read the landscape voltage-drop guide. Catalog examples later on this page include 12V landscape wells and 120V line-voltage families. Do not put 120V SKUs on an EMCOD ESL.

2700K or 3000K for trees?

Both can work. 2700K generally appears warmer and softer. 3000K generally appears slightly cleaner or crisper. Neither is automatically correct.

Kichler describes 2700K warm/soft white for warmer surroundings — brown or cedar, natural walls or stonework, and foliage with red, orange, or yellow tones, with oak trees as an example. Manufacturer: Kichler Lighting VOLT notes most residential work uses 2700K warm white. Manufacturer: VOLT Lighting Still match bark color, foliage, adjacent architecture, other landscape lighting, and ambient context.

Outdoor CCT rules and DarkSky

Some jurisdictions, projects, DarkSky-oriented specifications, and local ordinances may limit outdoor CCT. Check current project and local requirements. DarkSky Approved luminaire criteria state that the light-source CCT shall not exceed a nominal 3000 K. That is a product-certification limit, not a statement that California requires all outdoor lighting to be 3000K or lower. Authority / independent: DarkSky International

Does CRI matter for trees?

CRI is a color-rendering metric. Higher CRI can improve fidelity of foliage, bark, stone, and adjacent finishes relative to a reference illuminant. That is not the same as claiming 90+ CRI automatically makes leaves look better. FX Luminaire publishes 80+ CRI on the RS uplight family as a manufacturer specification for those products, not as a tree-lighting law. Manufacturer: FX Luminaire

Should I use a well light or a bullet spotlight for a tree?

Choose the housing for aiming, daytime visibility, and maintenance — then confirm photometry. Neither style is the required tree light.

Well / in-grade versus bullet / directional spotlight. Manufacturer architecture guidance, not a product ranking.
Topic	Well / in-grade	Bullet / directional spotlight
Visual discretion	Housing sits flush or below grade, so the fixture is usually less visible in daytime turf or paving.	Hardware remains visible above grade unless planting conceals it.
Mowing / foot traffic	VOLT: flush well lights are intended for turf where mowers pass over, or hardscape with foot traffic, when installed level with the surface.	VOLT: stake spotlights sit in lawn or beds and can conflict with mowing if placed in the travel path.
Aiming	Aiming range depends on the model. Some wells are more limited once installed in a can.	Typically easier to pan and tilt, including as the tree grows.
Drainage / installation	In-grade cans need drainage, correct burial, and listing appropriate to the location. Follow the manufacturer instructions for the exact model.	Stake or surface mount is usually simpler to relocate. Still keep splices dry and listed.
Tree-uplight role	Useful when the design must hide hardware at the base of a tree or column.	VOLT: spotlights / bullets are the usual directional tool for uplighting trees and for techniques that need aiming control.

VOLT: spotlights are also called uplights, directional lights, or bullets; well lights install flush or below grade. Manufacturer: VOLT Lighting VOLT lawn-care note: quality well lights sitting level with turf are less likely to be damaged by mowers; stake spotlights in lawns need careful placement. Manufacturer: VOLT Lighting

Layer order

Aim uplights at night.
Add a second side if people see more than one face.
Only then add moonlighting for ground pattern and canopy shadow.

When should I add moonlighting instead of more uplights?

Moonlighting uses fixtures mounted higher in or near the canopy aiming downward to create softer downward illumination and branch or leaf shadows. It is a layer, not an automatic replacement for uplights.

It is most often discussed for large oaks, broad canopies, and paths or patios below the tree. Kichler describes a 60° accent about 20–25 ft from the ground, at least four feet above the lowest branch tier, with cowls so the source is less visible from below, and says uplighting and downlighting can be used together. Manufacturer: Kichler Lighting

Safety: tree-mounted or elevated installation should follow manufacturer instructions and appropriate professional practice. Kichler specifies a tree-mount junction box with standoff screws, slack for growth, and routing on the least-visible side of the trunk. Do not improvise tree wiring.

How does a dark backyard differ from a tree near a streetlight?

Perceived brightness depends on contrast. A fixture output that looks dramatic in a dark yard may look weak beside streetlights, commercial lighting, or bright architecture. Do not apply a universal lumen multiplier; re-aim and re-evaluate photometry against the actual ambient scene.

Will the tree grow out of the lighting layout?

Often, yes. Palms gain height. Canopies expand. Branches redirect or block beams. Roots and irrigation change where a fixture can stay. Adjustable fixtures and accessible placement make future re-aiming easier. Kichler also notes leaving extra wire at the base for growth on tree-mounted work. Manufacturer: Kichler Lighting

Avoiding glare

Aim light at the tree, not into pedestrian sightlines, windows, drivers, neighboring property, or open sky where that can be avoided. Use shielding, aiming, and fixture placement. Kichler cowls reduce source visibility on downlights. DarkSky’s responsible-lighting principles include directing light only where it is needed and using no more brightness than necessary. Authority / independent: DarkSky International This section is aiming practice, not a code claim.

Common tree uplighting mistakes

Choosing by wattage alone instead of beam, candela, and photometry.
Using a wide flood on a tall, narrow palm.
Placing an oak uplight too close to the trunk so the beam never opens into the canopy.
Lighting only the trunk and ignoring canopy mass.
Using one extremely bright fixture where several directions would work better.
Ignoring how many sides people actually see.
Ignoring ambient light from streets, architecture, or neighboring sites.
Overusing the highest-output fixture in the family.
Failing to re-aim as the tree grows.
Ignoring glare toward people, windows, streets, and neighbors.
Assuming more lumens always means better tree lighting.
Ignoring manufacturer photometry and aiming by guess.

Worked examples

Projekt Supply design starting examples

Queen / tall feather palm, about 25–35 ft, patio view

Starting approach: one directional uplight, narrow beam (Kichler 10–15° trunk/column analog), close-to-trunk placement, aimed vertically into the crown. Add a second fixture only if there are multiple viewing sides, a thick trunk, a crown that lacks dimension, or the tree is a major walk-around feature.

Projekt Supply design starting example.

Mature oak, about 30 ft tall × 40 ft spread, house + street

Starting approach: multiple fixtures — one emphasizing trunk and primary branching, others opening into canopy. Kichler’s medium-deciduous method (two 35° rather than one 60°) is the closer published analog than the 60–100 ft large-tree recipe. If the upper canopy remains dark, evaluate an additional lighting direction or moonlighting rather than automatically selecting one extremely bright flood.

Projekt Supply design starting example.

Catalog examples at Projekt Supply

These public catalog records do not list beam angle in degrees, lumens, or candela. Request manufacturer photometry / IES before ordering. Do not specify throw from wattage.

Use these families for housing and aiming architecture — 12V well, directional spot, flood-coded well — not as a brightness spec. L25S / L25F are Dabmar optic codes, not published degree values. Examples below are 2700K (27K) configurations that exist on these families.

When the tree is on a 12V landscape run

Use a 12V in-ground well on an EMCOD ESL or other landscape transformer. These are housing examples, not photometric recommendations. 7W is load, not throw.

LV25-L7-27K-WBS — LV25
In-ground well · 12V landscape voltage · 27K
Beam angle not listed · lumens not listed · request photometry / IES before ordering
Listed load 7W — electrical load, not throw.
12V brass in-ground well for turf or planting. Use this family when the tree is on a landscape transformer and hardware should disappear. 7W is listed load, not throw.
View LV25 family
LV24-L7-27K-ABZ — LV24
In-ground well · 12V landscape voltage · 27K
Beam angle not listed · lumens not listed · request photometry / IES before ordering
Listed load 7W — electrical load, not throw.
12V brass well with grill. Same landscape-voltage class as LV25; the grill face is the mowing / debris difference, not a photometric one.
View LV24 family
LV306-L7-27K-BZ — LV306
In-ground well · 12V landscape voltage · 27K
Beam angle not listed · lumens not listed · request photometry / IES before ordering
Listed load 7W — electrical load, not throw.
12V cast-aluminum well. This family has higher listed loads than the brass 27K rows, still with no published beam degrees or lumens. It is not a 120V DW4701 substitute.
View LV306 family

When you need a directional spotlight

Use a bullet / directional family to aim up a trunk. These are architecture examples, not photometric recommendations.

DPR21-L7-27K-BZ — DPR21
Directional spotlight · 120V line voltage · 27K
Beam angle not listed · lumens not listed · request photometry / IES before ordering
Listed load 7W — electrical load, not throw.
Directional spotlight / bullet. Use this family when you need adjustable aiming up a trunk. Request photometry before treating wattage as throw.
View DPR21 family
DPR38-L25S-27K-BZ-GL — DPR38-GL
Directional spotlight · spot-coded · 120V-277V line voltage · 27K
Beam angle not listed · lumens not listed · request photometry / IES before ordering
Listed load 25W — electrical load, not throw.
Spot-coded directional spotlight (L25S is a Dabmar optic code, not a verified degree). Request the IES / spec sheet before ordering.
View DPR38-GL family

When you need a flood-coded directional

Compare a flood-coded spotlight when the target is broader mass. L25F is an optic code, not a published degree. Get the IES file.

DPR38-L25F-27K-BZ-GL — DPR38-GL
Directional spotlight · flood-coded · 120V-277V line voltage · 27K
Beam angle not listed · lumens not listed · request photometry / IES before ordering
Listed load 25W — electrical load, not throw.
Flood-coded directional spotlight (L25F is a Dabmar optic code, not a verified degree). Request photometry; do not shop this row by 25W.
View DPR38-GL family

When a well light is the housing, not the brightness spec

A flood-coded well can hide hardware. It still needs photometry. 25W is load, not throw.

DW4701-L25F-27K-BZ — DW4701
In-ground well · flood-coded · 120V-277V line voltage · 27K
Beam angle not listed · lumens not listed · request photometry / IES before ordering
Listed load 25W — electrical load, not throw.
Flood-coded well light. Use when hardware must disappear and the target is broader mass — after you have photometry, not because it is 25W.
View DW4701 family

When hardware must disappear

Use an in-ground well family for turf or paving. Confirm aiming range and photometry on the exact model.

DW4701-L25S-27K-BZ — DW4701
In-ground well · spot-coded · 120V-277V line voltage · 27K
Beam angle not listed · lumens not listed · request photometry / IES before ordering
Listed load 25W — electrical load, not throw.
In-ground well / discreet housing, spot-coded LED option. Request IES before assuming it will throw to a tall crown.
View DW4701 family
DW4751-L25S-27K-BZ — DW4751
In-ground well · spot-coded · 120V-277V line voltage · 27K
Beam angle not listed · lumens not listed · request photometry / IES before ordering
Listed load 25W — electrical load, not throw.
Second Dabmar well family. Same catalog gap: no published beam degrees or lumens on the public record.
View DW4751 family

Compare products

These are architecture examples, not required choices. The 40K directional floods in the catalog are 4000K — cooler than the 2700K/3000K discussion above — so they are not used as tree starting examples here.

Need a shielded path light instead of a tree uplight? How to pick a bollard

Common tree uplighting questions

How many lights do I need to uplight a palm tree?: A slim palm with one primary view often starts with 1 narrow uplight, about 10–15°, placed 1–3 ft from the trunk. Add fixtures for extra viewing sides or trunk mass — not as a required 2–3 count.
How many uplights do I need for an oak tree?: A wide canopy often needs more than one lighting direction. Kichler prefers two 35° accents over one 60° flood for medium deciduous trees. One narrow uplight may light the trunk and leave the canopy dark.
Why is my tree dark at the top?: Usually the beam is too wide, too close, or aimed at the trunk — not a lack of watts. Use photometry for throw, then aim at night. If the crown stays dark, choose a narrower beam or another direction before more wattage.
How wide is a 15° beam vs a 60° beam at 20 ft?: A Projekt Supply geometric estimate: about 5.27 ft wide at 15° versus about 23.09 ft at 60°, same 20 ft distance. That is not manufacturer photometry.

These values are design starting points, not universal fixture prescriptions. Final performance depends on exact tree geometry, photometrics, ambient light, fixture output, aiming, and field adjustment.

Return to the lighting guides. Related product families: LV25, LV24, LV306, DPR21, DPR38-GL, DW4701, DW4751.

Technical Sources & References

Kichler Lighting — Tree Lighting Techniques & TipsManufacturer product pageManufacturer application guide for fixture count, beam angles, viewing angles, grazing, and moonlighting / tree-mount practice.
Kichler Lighting — Landscape Lighting FundamentalsManufacturer product pageManufacturer guidance for 10–15° trunk/column spots, 35° and 60° deciduous recipes, lumens versus watts, and 2700K oak/warm-surroundings notes.
VOLT Lighting — How to Choose the Best Landscape Lighting for Your Home & YardManufacturer product pageManufacturer definitions of spotlights, well lights, flood lights, lumens, wattage, beam spread, and color temperature.
VOLT Lighting — How Landscape Lighting Affects Lawn CareManufacturer product pageManufacturer note that flush well lights are intended to sit level with turf so mowers pass over them, while stake spotlights sit above grade.
FX Luminaire — RS uplight photometry (LED20WFL / LED35WFL)Manufacturer specification sheetManufacturer photometry example: 35° beam, delivered lumens, center-beam candlepower, CRI 80+, and beam-width-at-distance tables. Not a Dabmar specification.
DarkSky International — DarkSky Approved Luminaires guidelines v3.1Independent technical sourceProduct-certification criteria: DarkSky Approved luminaires shall not exceed a nominal 3000 K CCT. This is not a claim that California requires all outdoor lighting to be 3000K or lower.
U.S. Department of Energy — Lumens and the Lighting Facts LabelIndependent technical sourceIndependent explanation that lumens measure light output and watts measure energy use.
NIST — SI Units: CandelaIndependent technical sourceCandela is the SI unit of luminous intensity — light in a given direction.
Projekt Supply — Geometric beam-diameter approximationProjekt Supply calculationdiameter ≈ 2 × distance × tan(beam angle / 2). Teaching estimate only; use manufacturer IES/photometry for fixture selection.