Lux to Foot-Candles Converter
Enter an illuminance value in lux and get the equivalent in foot-candles — the US and imperial unit used in lighting standards, architectural specifications, and photometry reports.
Exact conversion
The lux-to-foot-candle relationship is fixed by definition: one square metre contains exactly 10.763910… square feet, making the conversion factor a precise constant, not an approximation.
One reading, one point
Illuminance varies across a surface and with distance from the source. A single meter reading tells you the level at that spot — not the average for the whole room.
What is lux?
The SI unit of illuminance
Lux (symbol: lx) is the International System of Units (SI) measure of illuminance — the luminous flux per unit area falling on a surface. One lux equals one lumen per square metre. It is the standard unit used in European and international lighting standards, safety regulations, and photometric measurements. Foot-candles (fc) are the equivalent US and imperial unit: one foot-candle equals one lumen per square foot.
Enter your lux reading to get the foot-candle equivalent instantly — useful when working with US lighting codes or comparing measurements from different standards.
Because a square metre is larger than a square foot, one foot-candle is a larger unit of illuminance than one lux. The exact conversion factor comes from the definition of the foot: 1 ft = 0.3048 m, so 1 ft² = 0.09290304 m², and 1 fc = 1 lm/ft² = 1/0.09290304 lx ≈ 10.7639 lx.
fc = lux ÷ 10.7639To go in the other direction — foot-candles to lux — multiply by 10.7639. The full constant is 10.763910416709722, derived from the exact SI definition of the foot.
Knowing the foot-candle or lux value is most useful when you compare it against established reference levels. According to the Illuminating Engineering Society (IES) and international lighting guidelines, a dim residential corridor needs around 50 lux (4–5 fc), while a living room for general tasks sits at 100–200 lux (9–19 fc). Office and school environments typically require 300–500 lux (28–46 fc) at the task surface to support sustained reading and writing without eye strain.
Retail and supermarket floors are commonly specified at 750 lux (70 fc) to make merchandise colours vivid and appealing. An overcast outdoor sky provides roughly 1 000 lux (93 fc), a bright cloudy day around 10 000 lux (929 fc), and direct sunlight on a clear summer day can reach 100 000 lux (9 290 fc) or more. Photography and video production use foot-candles extensively because US film-industry lighting meters and older equipment report in fc. If your meter shows foot-candles and a lighting code specifies lux, this converter gives you the exact value to check compliance.
This calculator converts the unit only — it does not measure or estimate the actual illuminance in your space.
A single reading captures one point in space
Illuminance falls off with the square of the distance from the light source and varies significantly across a room or work surface. Lighting standards specify maintained average illuminance levels, not the peak at one spot. For compliance verification, take multiple readings across the task area and average them according to the relevant standard (IES, EN 12464, or local code).