Definition
LM-80 (IES LM-80-20, 'Approved Method: Measuring Luminous Flux and Color Maintenance of LED Packages, Arrays, and Modules') is the industry-standard test method for measuring how LED light output and color degrade over time under controlled temperature conditions. LED packages are tested at a minimum of two temperatures (typically 55°C and 85°C, plus a third manufacturer-specified temperature) for a minimum of 6,000 hours (preferably 10,000+ hours). Luminous flux and chromaticity are measured at regular intervals. LM-80 data is the required input for TM-21 lifetime projections — without LM-80 test data, any '50,000 hour lifespan' claim is unverifiable marketing. LM-80 does NOT test complete luminaires (that's LM-84/TM-28) — it tests the LED component alone. However, LM-80 data is the foundation of all LED reliability claims and is the #1 document procurement professionals should request.
Key Data
| Parameter | Value / Explanation |
|---|---|
| Test duration | Minimum 6,000 hours (8.2 months). 10,000+ hours preferred for reliable TM-21 projection. |
| Test temperatures | 55°C + 85°C + manufacturer-chosen third temperature. Data at actual operating temp is critical. |
| What it measures | Lumen maintenance (% of initial output) and chromaticity shift (Δu'v') over time at constant current/temperature. |
| What it does NOT test | Complete luminaire (driver, optics, thermal path), lumen depreciation of the full system, warranty validation. |
| TM-21 projection | Extrapolates LM-80 data to project L70/L80/L90 lifetime. Max projection = 6× test duration. |
| Why it matters for B2B | LM-80 is the only evidence-based way to compare LED quality claims between manufacturers. |
Application Guide
LED chip procurement
Request LM-80 report for the specific LED model at the drive current used in the luminaire
LM-80 data at 350mA doesn't apply to the same LED driven at 700mA
Luminaire procurement
Request LM-80 + TM-21 report, and the in-situ temperature test (ISTMT) data
LM-80 at 55°C means nothing if the actual LED junction temperature in the luminaire is 85°C
Warranty negotiation
Tie warranty lumen depreciation thresholds to TM-21 projected values
A 10-year warranty with L70 at 50,000h TM-21 projection is defensible; without LM-80, it's a guess
Conclusion & Procurement Recommendation
For B2B LED procurement: never accept a lifetime claim without LM-80 test data. Key procurement requirements: (1) Request LM-80 reports from an ISO 17025 accredited laboratory (not in-house manufacturer testing), (2) Verify the test was conducted at the actual drive current and temperature the LED will experience in the luminaire, (3) Require TM-21 projection report (LM-80 data alone doesn't give you the L70 number — TM-21 extrapolation does), (4) For projects >500 fixtures: require ISTMT (In-Situ Temperature Measurement Test) demonstrating actual LED junction temperature in the installed luminaire. Without LM-80, '100,000 hour lifetime' is marketing fiction.