Lux to Foot-Candles Converter (and Reverse) + Chart
Lux to Foot-Candles Converter (and Foot-Candles to Lux)
If you've ever compared a US lighting chart against a European one, you've run into the two units of illuminance: lux and foot-candles. They measure the same thing — how much light lands on a surface — just over different areas. Converting between them is quick once you know the single number that links them, and this guide gives you the formula, worked examples in both directions, and full lookup tables.
The short version: 1 foot-candle = 10.764 lux. Multiply or divide by that and you're done. To get a reading to convert in the first place, you can measure lux with your phone and apply the math below.
📲 Get the reading, then convert
Kelvin Light Scale measures lux straight from your iPhone. Take the reading, then use the formula here to convert to foot-candles — or the reverse.
The conversion formula
One foot-candle equals one lumen per square foot; one lux equals one lumen per square meter. Since there are about 10.764 square feet in a square meter, the conversion factor is simply 10.764.
| To convert | Formula |
|---|---|
| Lux → foot-candles | foot-candles = lux ÷ 10.764 |
| Foot-candles → lux | lux = foot-candles × 10.764 |
For a fast mental estimate, round to “1 fc ≈ 10 lux.” It's close enough to sanity-check a reading from the app before you reach for a calculator.
Lux to foot-candles
To convert a lux reading to foot-candles, divide by 10.764. For example, a desk measured at 500 lux is 500 ÷ 10.764 ≈ 46.5 foot-candles. Here are common values:
| Lux | Foot-candles |
|---|---|
| 50 lux | 4.6 fc |
| 100 lux | 9.3 fc |
| 200 lux | 18.6 fc |
| 300 lux | 27.9 fc |
| 500 lux | 46.5 fc |
| 750 lux | 69.7 fc |
| 1,000 lux | 92.9 fc |
So if your phone reads 300 lux at a desk, that's about 28 foot-candles — right in the general office range.
Foot-candles to lux
To go the other way, multiply foot-candles by 10.764. A workbench specified at 75 foot-candles is 75 × 10.764 ≈ 807 lux. Common values:
| Foot-candles | Lux |
|---|---|
| 5 fc | 53.8 lux |
| 10 fc | 107.6 lux |
| 20 fc | 215.3 lux |
| 30 fc | 322.9 lux |
| 50 fc | 538.2 lux |
| 75 fc | 807.3 lux |
| 100 fc | 1,076.4 lux |
This direction is handy when a US specification is in foot-candles but your meter, like most phone apps, reads in lux — convert the target to lux and compare directly to your reading.
💡 Pro tip
Don't mix the rounded and exact factors in the same calculation. Use 10.764 for accuracy, or 10 for a quick estimate — just be consistent. The 10 vs. 10.764 difference is about 7%, which matters when you're close to a target threshold.
Why two units exist
It comes down to measurement systems. The United States and a few other regions use foot-candles, built on the imperial square foot, while most of the world uses lux, built on the metric square meter. International projects, imported fixtures, and global lighting standards routinely mix the two, which is why converting is a everyday task for designers, electricians, photographers, and facility managers. Whichever your local standard uses, a reading from a phone meter converts to the other in one step.
Getting a reading to convert
- Open a lux meter app and allow access to your phone's sensors.
- Place the phone at the surface you care about, sensor facing the light.
- Read the lux value once it settles.
- Apply the formula — divide by 10.764 for foot-candles, or compare directly if your target is already in lux.
✅ The verdict
Lux ÷ 10.764 = foot-candles; foot-candles × 10.764 = lux. Memorize the factor, keep the tables above handy, and you can move between any two lighting charts instantly.
Converting between lux and foot-candles is one of the simplest pieces of lighting math — one factor handles both directions. Take a reading, apply it, and you're speaking whichever unit your project needs. You can grab a lux reading now and convert it in seconds.
Measure in lux, convert to anything
Kelvin Light Scale reads lux, color temperature, and exposure from your iPhone — take the reading, then convert with the formula above. Free to start, with pro tools when you need them.
Frequently asked questions
How do you convert lux to foot-candles?
Divide the lux value by 10.764. For example, 500 lux ÷ 10.764 ≈ 46.5 foot-candles. For a quick estimate you can divide by 10 instead, which is within about 7% of the exact figure.
How do you convert foot-candles to lux?
Multiply the foot-candle value by 10.764. For example, 50 foot-candles × 10.764 ≈ 538 lux. Rounding the factor to 10 gives a fast approximation.
How many lux is 1 foot-candle?
One foot-candle equals approximately 10.764 lux, because a foot-candle is one lumen per square foot and there are about 10.764 square feet in a square meter.
How many foot-candles is 500 lux?
500 lux is about 46.5 foot-candles (500 ÷ 10.764). This is a common office desk level, which US charts list as roughly 50 foot-candles.
Why are there two different units for light levels?
Foot-candles are based on the imperial square foot and used mainly in the US, while lux is based on the metric square meter and used in most of the world. International projects and standards often mix both, so conversion is routine.
What does my phone app measure, lux or foot-candles?
Most phone light meter apps report lux, since it's the international standard unit. To get foot-candles, take the lux reading and divide by 10.764 — or check whether your app offers a foot-candle display option.
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