One of the most important parts of planning any lighting, whether it’s new construction or a remodel, is making sure that the space is properly lit. To do this, you have to know how many footcandles you need. But what are footcandles? You may have noticed us mention them from time to time in past blog posts. In this post, we will take a deeper dive into what footcandles are and how many you’ll need for your lighting project.

What are footcandles?

Footcandles (or fc) are a common unit of measurement for determining light intensity. Before there was electricity, candles provided the majority of light. To determine a standard guideline for how much light was needed for a space, a candle was set one foot away from a one square foot surface. The light used to properly illuminate that one square foot of space became known as a footcandle. Today, footcandles are commonly referred to as lumens. One footcandle is equal to 1 lumen per square foot.

1 fc = 1 lumen/ft2

We can’t talk about footcandles without mentioning lux (lx). Lux is the metric system equivalent to footcandles. It is the same general idea as footcandles, but the area being lit is one square meter. One lux equals 1 lumen per square meter.

1 lx - 1 lumen/m2

Converting footcandles to lux is very simple. One footcandle is equal to approximately 10 lux (or 10.76 lx).

1 fc = 10 lx

So if you have 50 fc, you will have around 500 lux (50 x 10). Alternately, if you 1,000 lux then, you would have around 10 fc (1,000 ÷ 10).

Note: By multiplying or dividing by 10 lx, you are getting a general estimate. For the exact number of lux, you will need to use 10.76.

Why are footcandles important?

Footcandles and lux are the two most important measurements when it comes to planning any lighting. Without them, we would have no way to measure the amount of light being produced by a fixture. We also wouldn’t be able to tell how much light is needed to properly illuminate a space at comfortable levels. In fact, light levels are so important that there are state and local guidelines to ensure buildings have adequate light. Depending on the industry, the Occupational Safety and Health Administration (OSHA) has mandatory light levels. These regulations are in place to ensure work sites are well lit and safe for employees and customers.

How many footcandles do I need for my space?

Recommended footcandle amounts will vary based on a variety of factors, including the size and planned use of the space being lit. You must also follow any state and local regulations that dictate the amount of lighting needed for certain areas. As mentioned earlier, this is for safety reasons.

So, how many footcandles do you need? The tables below have average footcandle and corresponding estimated lux amounts for a wide range of commercial and residential applications. Keep in mind that these are estimates and should only be used as a reference or starting point. You should always refer to a lighting designer to determine the correct amount needed for any project.

Again, these are simply average footcandles. Every installation is different and will require its own set of footcandles. These are simply to give you a general idea of what you will need. If you have further questions about footcandles or need help finding a fixture that meets the footcandle requirements of your project, speak with one of our US-based lighting experts at 1-800-624-4488.