Lumens vs Footcandles: What Are The Differences, Which is More Important?

Lighting technology has grown rapidly over the years. Today there are hundreds of thousands of energy efficient and energy saving LED lighting options available in the market today. While lighting technologies may have changed over the past few decades, two industry terms have remained the same: lumens and footcandles.
Facility managers and sustainability leaders looking into LED lighting retrofits or upgrades for their facilities are often confused about the industry terms foot-candles and lumens. In this lumens vs footcandles article we breakdown the terms so you can better understand them as you plan out your LED lighting project.

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What is the difference between lumens and footcandles?

Lumens and footcandles are both measurements of light.

Lumens is a measure of luminous flux, or the flow of light. Lumens measure the amount of visible light emitted from a source of light. The more lumens you have, the brighter the space.

A foot candle measures the amount of light on a surface, or the intensity of light, as opposed to the flow of light. Foot candles equal one lumen one square foot. The word foot candle does stem from a time when candlepower was the main light source.

A foot candle is equal to about 10 lumens or one lux. Lux is the same as lumen, they both measure luminous intensity. Lux is in the International System of Units (SI), which is the modern form of the metric system. A lux is equal to one lumen per square meter.

Are lumens or foot candles more important?

Foot candles are more important for reading light levels when it comes to your facility. You need to know how much light is illuminating the area in question, not how much light is coming from the lighting fixture. At the same time, foot candles will show you a true reading of how much illumination you have on each surface in your building and will take natural light loss into account, unlike lumens. Read more about foot candles here.

As lighting professionals, we rely on foot candles to calculate what type of lighting you currently have at your facility and what type of lighting you need in order to follow suggested lighting levels. When we audit commercial facilities, one of the first things we do is obtain a foot candle measurement for each area of your facility.

Following industry suggested lighting levels and guidelines help ensure your employees are working in areas that are safe and productive. If you don’t have enough foot candles for any given space, your employees may deal with headaches, eye strain, or find it difficult to perform detailed tasks. 

Before and after images of increases in foot-candles after LED retrofit projects:

How many footcandles do I need?

Which LED product is best for your facility? That all depends on what each space is used for and other factors, such as mounting positions available and obstructions your site may have.

As a commercial lighting company, we use light meters to determine what the ideal lighting situation is for your facility, but to be even more specific we conduct photometric layouts. A photometric layout will show you exactly how much light is illuminating the intended surfaces and how much a LED lighting retrofit can increase your foot candle measurements.

A commercial lighting upgrade doesn’t need to be complicated. With so many measurements to take and calculate, let us do the work for you. We offer an audit as part of your LED lighting retrofit turnkey package when you choose us. Reach out: (800) 834-8737 or check us out online.