Foot Candles to Lux Converter

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Enter a foot-candle reading or lighting requirement to find the equivalent surface illuminance in lux.

Advanced options
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How to use our Foot Candles to Lux Converter

  1. Enter the surface light reading or requirement in "Foot-candles (fc)." You can use a decimal, scientific notation such as 1e-3, or a number followed by fc.
  2. Select "Calculate" to see "Illuminance in lux."
  3. Open "Advanced options" if a report, meter, or specification requires a certain number of decimal places.
  4. Use the lux result only for the same illuminance value in metric units. A result of 0 lx means the entered value was 0 fc.
Example inputs for Foot Candles to Lux Converter
Example inputs for Foot Candles to Lux Converter

Definitions

Illuminance: Light reaching a surface.

Foot-candle (fc): A US customary unit of illuminance.

Lux (lx): The SI metric unit of illuminance.

Lumen (lm): A unit of total visible light output from a source, not light measured at a surface.

Common mistakes and quick fixes

Mistake: Entering a fixture's lumen rating as foot-candles.
Fix: Enter light measured or specified at a surface. Lumens are total light output, while foot-candles measure light reaching a surface.

Mistake: Entering a lux value in the foot-candle field.
Fix: This converter goes only from foot-candles to lux. Start with the value labeled fc.

Mistake: Typing a comma incorrectly, such as 1,01.
Fix: Use commas only for thousands groups, such as 1,000. Use a decimal point for fractional values.

Limitations & Key Assumptions / Boundary Conditions

  • This is a unit conversion only. It does not determine whether a lighting level is suitable for a room, task, or safety requirement.
  • A meter reading applies to its measurement location and time. Light can vary across a room because of distance, shadows, surface reflectance, and fixture placement.
  • Enter foot-candles, not a fixture's lumen rating, wattage, or color temperature.
  • Displayed rounding can hide small differences. Select more decimal places when a report or specification needs them.

Methodology

Conversion method

The converter multiplies the entered foot-candle value by 10.763910416709722 to calculate lux. This factor follows from the exact relationship that 1 foot equals 0.3048 meter.

lux = foot_candles * 10.763910416709722

Worked example

For 2.5 fc, multiply 2.5 by 10.763910416709722. The unrounded answer is 26.909776041774304 lx. With "Lux decimal places" set to 4, the displayed answer is 26.9098 lx.

2.5 fc * 10.763910416709722 = 26.909776041774304 lx

The decimal-place choice changes only the displayed result. The converter keeps the unrounded value for the calculation.