How to Calculate the Efficacy of an LED Light Fixture

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LED lighting fixtures have become increasingly popular due to their energy efficiency, long lifespan, and low maintenance costs. One of the most important metrics for measuring the efficiency of an LED fixture is efficacy, which is a measure of how much light is produced per watt of electricity consumed. In this blog, we will discuss how to calculate the efficacy of an LED fixture and why it is important.

Why is Efficacy Important?

Efficacy is an important metric for measuring the energy efficiency of lighting fixtures. The higher the efficacy, the more energy-efficient the fixture is, which means it consumes less electricity to produce the same amount of light. This translates to lower energy costs and a reduced carbon footprint. 

Additionally, higher efficacy fixtures can often provide better illumination than lower efficacy fixtures. This can be important in applications where high-quality lighting is critical, such as showrooms, retail stores and grocery stores.

Calculating Efficacy and Lumen Value

To calculate the efficacy of an LED fixture, you need to know two things: the amount of light produced by the fixture (lumens) and the amount of electricity consumed by the fixture (watts). Once you have these two values, you can use the following formula to calculate efficacy:

Efficacy (lm/W) = Total luminous flux (lm) / Total power input (W)


Most LED Lighting manufacturers will include the delivered lumen value for their light fixtures. But, if not you can calculate it yourself using a device called a photometer, which measures the amount of light produced by the fixture. 

The total power input can be calculated by adding up the wattage of all the LEDs in the fixture. For example, if a fixture has ten 10-watt LEDs, the total power input would be 100 watts.

What is the Typical Efficacy of LED Lights?

It is important to note that the efficacy of an LED fixture can vary depending on a number of factors, including the quality of the LEDs, the design of the fixture, and the operating temperature. 

It is important to consult with the manufacturer or a qualified lighting professional to ensure that you are calculating the efficacy accurately. 

Tip: If you’re looking for the efficacy of a Lumenture light fixture, you can find it on the first page of its specification sheet.

Choosing an Efficient Light Fixture

Efficacy is an important metric for measuring the energy efficiency of LED lighting fixtures. By calculating the amount of light produced per watt of electricity consumed, you can determine the efficiency of a fixture and compare it to other fixtures on the market. 

This can help you make an informed decision when selecting a lighting fixture and can ultimately lead to energy savings and a reduced carbon footprint.

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