Illuminance Converter
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Illuminance is the measure of how much luminous flux (raw light energy) is spread over a specific area. Whether you're an interior designer planning the lighting strategy for an office, a photographer metering a scene, or a botanist ensuring plants get enough grow-light exposure, understanding illuminance is essential to getting the right results.
However, light measurement standards differ significantly by industry and geography. The International System of Units (SI) measures illuminance in Lux (lx), signifying one lumen per square meter. In contrast, the United States often uses Foot-candles (fc), signifying one lumen per square foot. Attempting to guess these conversions or do the math in your head can result in dangerously underlit workspaces or overexposed photographs.
Our free Illuminance Converter eliminates the guesswork. Input your light meter reading, select your units, and instantly get mathematically precise conversions. It works effortlessly on both mobile devices natively using responsive browser technology.
How to Convert Light Measurements
- 1
Take a reading with your light meter or check your lighting specification sheet, and type the value into the main input field.
- 2
Use the 'From' menu to select the unit of your original reading (e.g., Foot-candle).
- 3
Use the 'To' menu to choose the final unit you need for your calculations (e.g., Lux).
- 4
The accurately converted light level will appear instantly in the result window.
Why Use This Tool?
- ✓Invaluable for photography exposure math
- ✓Ensures workspaces meet OSHA lighting requirements
- ✓Assists with grow-tent lighting equations
- ✓Mobile-friendly for on-site checks
- ✓100% Free with no login needed
Understanding Lux vs Foot-candles
What is Lux (lx)?
Lux is the metric standard for illuminance. Exactly 1 lux is equal to the illumination provided when 1 lumen of light is evenly spread over 1 square meter.
What is a Foot-candle (fc)?
A foot-candle is the imperial standard. One foot-candle is the illumination provided when 1 lumen is spread over 1 square foot. $1$ fc is roughly equal to $10.76$ lux.
Frequently Asked Questions
What is the difference between Illuminance and Luminance?
Illuminance (Lux) measures the light *falling onto* a surface. Luminance (Candelas/$m^2$ or Nits) measures the light *emitting from or reflecting off* a surface (like a computer monitor).
Is Illuminance the same as Lumens?
No. Lumens measure the *total* light output from a source (like a lightbulb) globally. Illuminance specifically measures how concentrated that light is when it hits a surface. An 800-lumen bulb produces high lux if focused like a laser, but low lux if spread across an empty room.
What is a Phot?
A phot (ph) is an older unit of illuminance used in the centimeter-gram-second (CGS) system. One phot completely equals 10,000 lux.
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