Illuminance measures how much light lands on a surface. Lighting designers in the U.S. use foot-candles (lumens per square foot); the rest of the world uses lux (lumens per square metre). Offices are typically lit to 300–500 lux.
How to use the Lux to Foot-Candles Converter
- Pick the unit you are starting from in the From menu and type your value.
- Pick the unit you want in the To menu. The heading changes to match – for example “Lux to Foot-candles Converter”.
- The most common illuminance units are shown below at the same time, so you can compare them at a glance.
- Type into any result to convert backwards, then use Copy results – the copied text starts with the heading for your chosen units.
Results update as you type. Everything is calculated in your browser.
How it works
Every illuminance unit is defined by an exact factor relative to the lux (the base unit). The calculator first turns the value you type into lux, then turns that into the unit you picked in the “To” menu and into each of the common units below it. This two-step method means any unit can be converted to any other – 3 units are available in each menu – and you can type into any field, including a result, to work in the other direction. Changing a unit menu keeps the quantity the same and just re-expresses it, and the page heading and copied results follow your choice.
How to convert illuminance units
- Choose the unit you have in the From menu and type the value, for example 500 lx.
- Choose the unit you want in the To menu, for example foot-candles. The page heading changes to “Lux to Foot-candles Converter”.
- The calculator multiplies by the lux factor of the “from” unit and divides by the factor of the “to” unit: 500 lx × 1 ÷ 10.76391 = 46.45152 fc.
1 lux in common units
| Unit | Value |
|---|---|
| Foot-candles (fc) | 0.09290304 |
| Phots (ph) | 0.0001 |
Lux conversion table
| Lux | fc | ph |
|---|---|---|
| 50 | 4.645152 | 0.005 |
| 100 | 9.290304 | 0.01 |
| 300 | 27.870912 | 0.03 |
| 500 | 46.45152 | 0.05 |
| 1,000 | 92.90304 | 0.1 |
| 10,000 | 929.0304 | 1 |
Formula
1 lx = 0.09290304 fc1 lx = 0.0001 phWorked example
Inputs — From: 500 lx.
Results — To = 46.45152 fc; Phots = 0.05 ph.
Frequently asked questions
Is lux the same as lumens?
No. Lux is lumens per square metre, the light falling on a surface.
How bright is direct sunlight?
Roughly 30,000–100,000 lux.
How much light do houseplants need?
Low-light plants manage with 500–1,000 lux; vegetables want 20,000 lux or more.
How do I change the units?
Pick any unit in the From and To menus. The value is converted in place, and the heading changes to show your conversion, for example “Lux to Foot-candles Converter”.
Can I type into any field?
Yes. Every field is editable, so you can start from whichever unit you have.
How many units can I convert between?
3 illuminance units, from the everyday to the specialised.
Which units are exact?
All factors here are exact by definition except astronomical and similar reference values, which use internationally agreed constants.
What formula does the Lux to Foot-Candles Converter use?
1 lx = 0.09290304 fc.