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To convert from Foot-candle (ft-cd) to Lux (lx), use the following formula:
Lux (lx)
= 10.76391× Foot-candle (ft-cd)
With 10.76391 is the ratio between the base units Lux (lx) and Foot-candle (ft-cd).
Let's convert 5 Foot-candle (ft-cd) to Lux (lx).
Using the formula:
5 × 10.76391 = 53.81955
Therefore, 5 Foot-candle (ft-cd) is equal to 53.81955 Lux (lx).
How many foot-candles are in one lux? One Lux (lx) contains 0.092903043596611268582 Foot-candles (ft-cd) — the inverse of the factor above. Multiplying by 10.76391 takes you from foot-candles to lux; multiplying by 0.092903043596611268582 brings you back.
Put in words: one foot-candle equals 10.76391 lux, so the foot-candle is the larger unit of this pair. Converting between them never changes the amount of illuminance being measured — only the size of the unit you count it in.
A foot-candle (ft-cd) is the standard unit of illuminance, or light intensity, in the imperial system.
It's a fundamental concept used in lighting design to ensure spaces are adequately lit.
A foot-candle measures the amount of light that falls onto a specific surface.
To be precise, one foot-candle is the illuminance on a one-square-foot surface from a uniform light source of one candela that is exactly one foot away.
This direct relationship makes the foot-candle an intuitive unit for creating lighting plans in the imperial system.
It's important not to confuse foot-candles with lumens. While lumens measure the total light output from a source (like a lightbulb), foot-candles measure how much of that light actually reaches a surface.
The foot-candle is the imperial counterpart to the lux (lx), which is the standard unit for illuminance in the SI or metric system.
Since many lighting specifications are international, understanding how to convert between them is essential.
The conversion is straightforward:
For quick reference, here's a simple comparison table:
| Feature | Foot-candle (ft-cd) | Lux (lx) |
|---|---|---|
| System | Imperial | SI / Metric |
| Definition | 1 lumen / square foot | 1 lumen / square meter |
| Conversion | 1 ft-cd ≈ 10.764 lx | 1 lx ≈ 0.0929 ft-cd |
Using foot-candle measurements ensures that different environments are lit correctly for safety, comfort, and function.
Lighting standards often provide recommendations for various spaces. Here are a few common examples:
Lighting design is one of the last fields where two unit systems are used side by side in the same document, so the conversion is worth carrying in your head.
The awkward number is simply the number of square feet in a square metre. A foot-candle is one lumen per square foot; a lux is one lumen per square metre. Spread the same lumen over the larger metric area and you get a smaller number, which is why lux values always look about eleven times bigger than the same light expressed in foot-candles.
For rough fieldwork many designers divide or multiply by 10 and accept the 7% error, but that shortcut does not belong in a specification that has to be verified with a meter.
The foot-candle has been formally superseded by the lux almost everywhere, yet it remains the working unit of North American lighting practice for a practical reason: the standards are written in it.
Recommended illuminance levels published by the Illuminating Engineering Society (IES), along with a great deal of building code, energy code and utility rebate documentation, are expressed in foot-candles. So are the calibration scales on much of the installed base of light meters. An engineer who converts everything to lux still has to convert back to demonstrate compliance.
There is also a convenient coincidence that helped the unit stick. At a distance of one foot, a one-candela source produces exactly one foot-candle — the definition is directly readable from the name, which makes it easy to reason about point sources without a calculator.
Have you ever wondered how experts decide how bright the lights should be in an office or a movie studio?
The answer often comes down to a measurement called lux.
Lux (lx) is the standard unit used to measure illuminance—the total amount of visible light that hits a specific surface.
In simple terms, it measures how bright a light appears when it lands on something, like your desk or the floor.
Think of it like this: lumens measure the total amount of light coming from a source, while lux tells you how much of that light is actually landing on a specific area.
This measurement is crucial in many fields, from lighting design and photography to growing plants indoors.
The measurement of lux is directly connected to lumens, which measure the total light output from a source.
The formula is straightforward:
One lux is equal to one lumen distributed evenly over an area of one square meter.
This can be written as: 1 lx = 1 lm/m<sup>2</sup>.
This simple lux to lumen formula is essential for calculating and ensuring the correct lighting levels for any space or activity.
Measuring lux is vital for creating safe, efficient, and optimal lighting conditions across various industries.
To prevent eye strain and accidents, companies use lux measurements to ensure lighting levels meet workplace safety standards.
This helps create a comfortable and productive environment for employees in offices and factories.
In indoor farming and greenhouses, providing the right light is critical.
Since each plant has unique light intensity needs, measuring lux allows growers to fine-tune the environment, optimizing plant growth and maximizing crop yields.
In photography and filmmaking, lighting is everything.
Cinematographers and photographers use lux measurements to control exposure and create the desired mood in a scene. Consistent lux levels ensure every shot looks exactly as intended.
To get precise readings, professionals use a special tool called a lux meter.
This handheld device has a sensor that you can place on any surface to measure the illuminance in lux instantly.
A lux meter takes the guesswork out of determining if a space is adequately lit for its intended purpose.
Here are some quick reference conversions from Foot-candle (ft-cd) to Lux (lx):
| Foot-candles | Lux |
|---|---|
| 0.000001 ft-cd | 0.00001076391 lx |
| 0.001 ft-cd | 0.01076391 lx |
| 0.1 ft-cd | 1.076391 lx |
| 1 ft-cd | 10.76391 lx |
| 2 ft-cd | 21.52782 lx |
| 3 ft-cd | 32.29173 lx |
| 4 ft-cd | 43.05564 lx |
| 5 ft-cd | 53.81955 lx |
| 6 ft-cd | 64.58346 lx |
| 7 ft-cd | 75.34737 lx |
| 8 ft-cd | 86.11128 lx |
| 9 ft-cd | 96.87519 lx |
| 10 ft-cd | 107.6391 lx |
| 20 ft-cd | 215.2782 lx |
| 30 ft-cd | 322.9173 lx |
| 40 ft-cd | 430.5564 lx |
| 50 ft-cd | 538.1955 lx |
| 100 ft-cd | 1076.391 lx |
| 1000 ft-cd | 10763.91 lx |
| 10000 ft-cd | 107639.1 lx |
For all Illuminance converters, choose units using the From/To dropdowns above.