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Illuminance ConverterConvert between lux, foot-candles, and phots for lighting measurements.

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Illuminance Converter

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

How to Use
1

Enter illuminance

Type the illuminance value.

2

Select units

Choose between lux, foot-candles, and phots.

3

Get the result

Converted illuminance appears instantly.

What Is Illuminance Converter?

An illuminance converter translates between units measuring the amount of light falling on a surface. Lux (lx) is the SI unit — one lumen per square meter. Foot-candles (fc) measure one lumen per square foot and are standard in US lighting design. Phot is the CGS unit equal to 10,000 lux, rarely used today but found in older references. Proper illuminance levels are specified by building codes for workplaces, schools, hospitals, and outdoor spaces.

Why Use Our Illuminance Converter?

  • Converts between lux and foot-candles for international lighting standards.
  • Essential for architects, lighting designers, and photographers.
  • Includes the phot for legacy reference compatibility.
  • Real-time conversion.

Common Use Cases

Lighting Design

Convert illuminance requirements between lux and foot-candles for international projects.

Photography

Understand light levels for exposure calculations.

Building Codes

Verify workspace lighting meets standards specified in either lux or foot-candles.

Horticulture

Convert light level measurements for indoor growing specifications.

Technical Guide

Illuminance is luminous flux per unit area — how much light hits a surface. • 1 lux = 1 lumen/m² • 1 foot-candle = 1 lumen/ft² = 10.764 lux • 1 phot = 1 lumen/cm² = 10,000 lux Typical illuminance levels: • Full moonlight: 0.25-1 lux • Street lighting: 5-30 lux • Office lighting: 300-500 lux • Surgery: 10,000-100,000 lux • Direct sunlight: 100,000 lux Do not confuse illuminance (lux, light on a surface) with luminance (cd/m², light from a surface). They measure different aspects of lighting.

Tips & Best Practices

  • 1
    1 foot-candle ≈ 10.76 lux. For quick estimates, multiply fc by 10.
  • 2
    Office lighting should be 300-500 lux (30-50 foot-candles).
  • 3
    A single 60W incandescent bulb provides about 800 lumens.
  • 4
    Illuminance (lux) measures light arriving at a surface; luminance (nits) measures light leaving a surface.

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Frequently Asked Questions

QHow many lux in a foot-candle?
One foot-candle equals approximately 10.764 lux.
QWhat is the recommended office lighting level?
Most standards recommend 300-500 lux (28-46 foot-candles) for general office work.
QWhat is the difference between lux and lumens?
Lumens measure total light output from a source. Lux measures how much of that light reaches a surface. Lux = lumens per square meter.
QWhat is a phot?
A phot is the CGS unit of illuminance equal to 10,000 lux (1 lumen per cm²). It is rarely used in modern practice.

About Illuminance Converter

Illuminance Converter is a free online tool from FreeToolkit.ai. All processing happens directly in your browser — your data never leaves your device. No registration required. No ads. Just fast, reliable tools.