LM-80 testing is a standardized method for measuring the lumen maintenance of LED light sources over time. Established by the Illuminating Engineering Society (IES) as LM-80-08, this test is critical for evaluating LED reliability and predicting long-term performance. The test involves operating LEDs under controlled conditions at specified drive currents and three case temperatures (typically 55°C, 85°C, and a third temperature selected by the manufacturer). Lumen output is measured at regular intervals—usually every 1,000 hours—up to a minimum of 6,000 hours, though data up to 10,000 hours provides more reliable projections.

The collected data is then analyzed using the IES TM-21 method to project lumen maintenance beyond the test duration. For example, if a tested LED maintains 90% of its initial lumens at 6,000 hours, TM-21 can estimate when it will reach L70 (70% of initial output), which is commonly defined as the end of useful life. It’s important to understand that LM-80 does not test LEDs in actual fixtures; instead, it evaluates individual LED packages, arrays, or modules. Factors such as thermal management, driver quality, and environmental conditions still influence real-world performance.

LM-80 compliance is increasingly required for Energy Star certification and many building codes, especially in commercial and outdoor lighting. Designers and specifiers should request LM-80 test reports from manufacturers to ensure product longevity and warranty compliance. In summary, LM-80 testing provides a consistent, scientific basis for comparing LED reliability, making it indispensable for modern lighting system design.