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Free Illuminance Converter

Convert between lux, foot-candles, and phot for lighting and photography measurements.

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Illuminance measures how much light actually falls on a surface, which matters for photography exposure settings, indoor lighting design, and workplace safety standards.

Lighting specifications mix metric lux with the older imperial foot-candle unit depending on the country and industry, so a converter is genuinely useful for reading equipment specifications or building codes written in a different unit than you're used to.

How it works

Enter an illuminance value, choose the unit you're converting from, and the unit you want to convert to. The tool applies the standard conversion factors between lux, foot-candles, and phot and returns the result.

  1. Enter value.
  2. Enter from.
  3. Enter to.
  4. Click Calculate to see your results.

Examples

Checking an office lighting standard

A recommended office lighting level of 500 lux converts to about 46.45 foot-candles.

Who should use it

  • Converting a lighting standard or building code requirement between lux and foot-candles.
  • Checking a photography light meter reading against a foot-candle-based exposure guide.

Industry applications

  • Architectural and interior lighting design
  • Photography and film production

Advantages

  • Covers the standard metric and imperial illuminance units used in lighting and photography.
  • Exact, standards-based conversion factors.

Common mistakes to avoid

  • Mixing up lux and foot-candle values when comparing lighting specifications from different regions.
  • Confusing illuminance (light falling on a surface) with luminance (light emitted or reflected from a surface), which are related but distinct measurements.

Best practices

  • When comparing lighting standards or equipment specs from different countries, convert to a single unit first to avoid an easy factor-of-ten misread.

Tips

  • Remember roughly "1 foot-candle ≈ 10.76 lux" as a quick mental check when skimming a lighting spec in an unfamiliar unit.

Frequently asked questions

Yes, with no signup and no limit on how many conversions you run.
Both measure light falling on a surface; lux is the metric (SI) unit based on lumens per square meter, while foot-candles is the imperial equivalent based on lumens per square foot. 1 foot-candle equals about 10.76 lux.
Phot is an older, rarely-used metric illuminance unit equal to 10,000 lux — occasionally seen in older scientific literature or legacy equipment.
Light meters measure illuminance to help determine correct exposure settings, and many lighting specification sheets for photography and film equipment are published in lux.

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