Lux to Foot Candles Converter
Enter an illuminance value in lux or foot candles and get the converted result instantly. Switch the direction with one click to go from foot candles back to lux. Below the converter you will find the exact formula, a full IES reference table by room type, and a plain-English explanation of what both units mean and when each one is used.
What are lux and foot candles?
Both lux (lx) and foot candles (fc) measure illuminance, which is the amount of light reaching a surface rather than the amount leaving a bulb. Lux is the SI (metric) unit: one lux equals one lumen per square metre. Foot candles are the equivalent imperial unit: one foot candle equals one lumen per square foot. Because a square metre contains 10.76391 square feet, one foot candle equals 10.76391 lux, and values in foot candles are always smaller than those in lux by exactly that ratio. Lux is used in international standards, building codes outside North America, and scientific measurement. Foot candles remain standard in US architectural specifications, theatrical lighting, and IES guidelines.
How to convert lux to foot candles (and back)
The conversion is a single multiplication. To go from lux to foot candles, multiply the lux value by 0.09290304. To go from foot candles to lux, multiply by 10.76391. For example, a recommended office illuminance of 500 lx equals 500 x 0.09290304 = 46.45 fc, which rounds to the 50 fc figure commonly cited in US office lighting guidelines. Going the other way, 50 fc x 10.76391 = 538 lx. The exact factor 10.76391041671 comes from the international definition of one foot as 0.3048 metres exactly: (1 / 0.3048)^2 = 10.76391...
Lux, foot candles, and lumens: what is the difference?
Lumens (lm) measure the total quantity of visible light emitted by a source, regardless of where it lands. Lux and foot candles measure how much of that light actually arrives at a specific surface. The same 800-lumen bulb spread over 10 square metres produces 80 lux; the same bulb focused onto 1 square metre produces 800 lux. Distance between source and surface matters enormously: doubling the distance quarters the illuminance (the inverse-square law). This is why specifying a space in lux or foot candles is the correct way to describe how well lit it is, rather than quoting the bulb wattage or total lumens.
Typical illuminance levels for common environments
A few benchmarks help put numbers in context. Moonlight produces roughly 0.1 lx (0.009 fc). A candle at one metre gives about 1 lx (0.09 fc). A residential living room lit for TV watching sits at 50-100 lx (5-9 fc). General office and classroom lighting runs 300-500 lx (28-46 fc). Retail display lighting for featured merchandise can reach 750-1000 lx (70-93 fc). An overcast outdoor sky provides around 1000-10000 lx (93-929 fc). Direct midday sunlight can exceed 100000 lx (9290 fc). These benchmarks are useful when calibrating a light meter reading or interpreting a lighting fixture datasheet.
IES recommended illuminance levels by space type
| Space type | Min (fc) | Recommended (fc) | Task area (fc) | Recommended (lux) |
|---|---|---|---|---|
| Office - general | 30 | 50 | 75 | 538 |
| Office - computer work | 20 | 30 | 50 | 323 |
| Retail - general sales | 20 | 30 | 50 | 323 |
| Retail - feature display | 50 | 75 | 100 | 807 |
| Classroom | 30 | 50 | 75 | 538 |
| Kitchen - counter | 30 | 50 | 70 | 538 |
| Bedroom - general | 10 | 20 | 30 | 215 |
| Bathroom - vanity | 30 | 50 | 70 | 538 |
| Warehouse - storage | 10 | 30 | 50 | 323 |
| Lobby / reception | 10 | 20 | 30 | 215 |
| Corridor / hallway | 5 | 10 | 20 | 108 |
| Outdoor parking | 0.5 | 2 | 5 | 22 |
Targets from the Illuminating Engineering Society Lighting Handbook. "Recommended" is the ambient room level; "Task area" is the directly lit work surface.
Frequently asked questions
How many lux is 1 foot candle?
1 foot candle equals exactly 10.76391041671 lux. This number comes from the fact that one square foot equals 0.09290304 square metres (since 1 foot = 0.3048 m exactly), so a lumen per square foot is a lumen per 0.09290304 square metres, which equals 10.76391 lumens per square metre, i.e. 10.76391 lux.
How do I convert lux to foot candles?
Multiply the lux value by 0.09290304. For example, 300 lux x 0.09290304 = 27.87 fc. Alternatively, divide by 10.76391 for the same result. The calculator above does both directions automatically.
What is the difference between lux and lumens?
Lumens measure the total light output of a source. Lux (and foot candles) measure how much light arrives at a surface. The same 1000-lumen source spread over 10 m^2 delivers 100 lux; focused onto 1 m^2 it delivers 1000 lux. To calculate illuminance in lux, divide lumens by the surface area in square metres.
Why do the US and international standards use different units?
The US retained the imperial foot-candle unit in professional lighting standards - especially IES codes and theatrical industry practice - long after most other countries adopted the SI system. Internationally, lux is used in ISO standards, IEC product data, and regulatory codes. Both units measure exactly the same physical quantity and convert via a fixed factor, so neither is more accurate or precise than the other.
How many foot candles do I need in my office?
The IES recommends 30-50 fc (roughly 323-538 lux) for general office ambient light, rising to 50-75 fc at the desk for sustained reading and computer tasks. These are average targets across the workspace; a dedicated task lamp on the desk can push the immediate work surface higher without overlighting the whole room.
Does this converter work for very high or very low values?
Yes. The conversion factor is a fixed ratio, so it works for any non-negative value from near-zero starlight to direct noon sunlight (over 100000 lux / 9290 fc). Enter the value in the input field and the result updates instantly.
What is the exact conversion factor between lux and foot candles?
The exact factor is 1 fc = 10.76391041671 lx, derived from 1 foot = 0.3048 m exactly, so 1 fc = 1 lm / (0.3048 m)^2 = 1 / 0.09290304 lx. The reciprocal is 0.09290304 fc per lux. Both values are exact because the foot is defined in terms of the metre by exact convention.