Lighting Quick Reference

Photometry Conversion Table

Check the most common lighting unit conversions in one cleaner reference page. Built for room lighting, displays, photography, and production teams that need quick answers first.

Lux ↔ Foot-candle1 nit = 1 cd/m²Lumens need area or angle

Some lighting units convert directly. Others need extra context like area, beam angle, or surface behavior before the math means anything.

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Most Common Lighting Conversions

These are the lighting relationships people usually need first.

Illuminance

1 fc = 10.7639 lx

Use this for room, task, and architectural lighting targets.

Display Brightness

1 nit = 1 cd/m²

This is the cleanest display luminance conversion.

Screen & Projection

1 fL = 3.42626 cd/m²

Useful when older screen specs meet newer display references.

Beam-Based Lighting

1 cd = 1 lm/sr

This works only when the beam's solid angle is known.

Where People Use These Units

Room and Building Lighting

Compare lux and foot-candle when you move between SI lighting plans and US lighting specs.

Display and Monitor Brightness

Use nits, cd/m², and foot-lamberts when checking screen brightness, HDR targets, or projection references.

Stage and Event Production

Quickly compare landing light levels and beam references without digging through older handbooks first.

Photography and Video Lighting

Switch between lux and foot-candle when using mixed lighting guides, meters, or exposure references.

Illuminance

Use these units when you care about how much light lands on a desk, floor, wall, working plane, or sensor.

If your job is about room lighting or set lighting levels, lux and foot-candle are usually the first units to check.

Lux (lx)

#1
Symbollx
Lux (lx)1
Foot-candle (fc)0.092903

Foot-candle (fc)

#2
Symbolfc
Lux (lx)10.7639
Foot-candle (fc)1

Luminance

Use these units when you care about how bright a screen, projector surface, sign, or glowing object appears.

For monitors and TVs, nits and cd/m² are the same value.

Candela per Square Meter (cd/m²)

#1
Symbolcd/m²
cd/m²1
Foot-lambert (fL)0.291863
cd/ft²0.092903

Nit (nt)

#2
Symbolnt
cd/m²1
Foot-lambert (fL)0.291863
cd/ft²0.092903

Foot-lambert (fL)

#3
SymbolfL
cd/m²3.42626
Foot-lambert (fL)1
cd/ft²0.318310

Candela per Square Foot (cd/ft²)

#4
Symbolcd/ft²
cd/m²10.7639
Foot-lambert (fL)3.14159
cd/ft²1

Know Before You Convert

These are the lighting relationships that look simple but are not fixed without extra context.

Needs Context

Lumens to Lux Needs Area

lux = lumens / area

Total light output is not the same as light level on a surface. You need the illuminated area.

Needs Context

Lumens to Candela Needs Beam Angle

candela = lumens / steradian

A narrow beam and a wide beam can have the same lumens but very different candela.

Needs Context

Lux to Nits Is Not a Fixed Pair

surface and geometry matter

Illuminance and luminance describe different things, so you need surface or display assumptions.

Built on Standard Photometry Definitions

The page keeps easy conversions easy, and it flags the places where lighting math needs extra assumptions. That keeps the reference practical without turning it into a misleading all-in-one matrix.

Frequently Asked Questions

Can I convert lumens directly to lux?

Only if you know the illuminated area. Average illuminance is lumens divided by square meters.

Is candela the same as lumen?

No. Candela measures intensity in a direction, while lumen measures total light output. You need solid angle to connect them.

Is a nit the same as candela per square meter?

Yes. In luminance and display work, 1 nit equals 1 cd/m².

How do I convert foot-candles to lux?

Multiply foot-candles by 10.7639.

Can I convert lux to nits directly?

Not as a fixed conversion. You need more information about the surface or display conditions.

Why is this not a giant full conversion matrix?

Because lighting units do not all describe the same quantity. A giant matrix would look convenient but often be physically wrong.