The Illuminance Converter transforms light intensity measurements between lux, foot-candles, and phot. Lux is the SI unit used internationally. Foot-candles are the imperial equivalent used in the US. Phot is a less common unit used in some scientific contexts. The tool converts between all three using exact factors.

How does Illuminance Converter work?

This tool applies standard illuminance conversion factors: 1 foot-candle = 10.7639 lux, 1 phot = 10,000 lux. You enter a value in one unit and see the equivalent in the other two.

Key Features

Converts lux, foot-candles, and phot
Exact conversion factors
Reference chart for common light levels
Bidirectional conversion
Six decimal place precision

Common Use Cases

When and why you might need this tool

Designing workplace lighting
Convert a lux specification to foot-candles to match US lighting standards.
Setting up photography lighting
Convert foot-candle meter readings to lux for documentation or equipment comparison.
Comparing international lighting standards
Convert European lux requirements to foot-candles for US compliance.
Evaluating natural light levels
Convert a foot-candle reading from a light meter to lux for a report.

How to Use This Tool

Step-by-step guide to get the best results

Enter a value

Type the illuminance and select the source unit.

View the conversions

The tool shows the equivalent in the other two units.

Copy the result

Copy the value you need.

Pro Tips

1
1 foot-candle = 10.7639 lux.
2
Office lighting typically requires 300-500 lux.
3
Direct sunlight is about 100,000 lux.
4
Lux is the SI standard. Foot-candles are used primarily in the US.

Frequently Asked Questions

What is the difference between lux and foot-candles?

Both measure illuminance (light intensity). Lux is the SI unit used internationally. Foot-candles are the imperial equivalent used in the US. 1 foot-candle equals 10.7639 lux.

Is my data sent to a server?

No. All conversion happens in your browser. Nothing is transmitted.

What is a phot?

Phot is a CGS unit of illuminance equal to 10,000 lux. It is rarely used today but appears in some older scientific literature.

When would I need this converter?

Lighting designers, photographers, and safety engineers commonly need to convert between lux and foot-candles when working with international standards or equipment from different regions.