LED Lifetime Estimator

Predict L70 (or L50) rated life using the Arrhenius temperature acceleration model. Enter reference test data, junction temperature, and activation energy — get realistic lifetime estimates for high‑power LEDs, COBs, and SMD packages.

Hours at reference temperature (LM‑80 data).
Typically 55°C, 85°C, or 105°C per test standard.
Estimated or measured LED junction temperature in operation.
Typical range: 0.3 eV to 0.7 eV (0.5 eV default for InGaN).
? High Power LED (70k hrs @85°C)
? COB LED (50k hrs @105°C)
? SMD 2835 (36k hrs @85°C)
? Automotive LED (100k hrs @65°C)
❄️ Well-cooled (Tj=45°C)
Privacy-first: All calculations run locally in your browser. No data is sent to any server.

Understanding LED Lifetime Estimation

LED lifetime is typically defined as the time when luminous flux degrades to a certain percentage of initial output – commonly L70 (70% lumen maintenance) or L50 (50% maintenance). The most trusted methodology follows IES LM-80 (measurement of lumen maintenance) and IES TM-21 (extrapolation of lifetime). This calculator applies the Arrhenius acceleration model, widely adopted by leading LED manufacturers (Cree, Lumileds, Osram, Nichia) to predict life at different junction temperatures.

? Acceleration Factor (AF) – Arrhenius Equation

AF = exp[ (Ea / kB) · (1/Tref – 1/Tj) ]

where kB = 8.617 × 10−5 eV/K (Boltzmann constant), T in Kelvin. The estimated lifetime: L(Tj) = L(Tref) / AF.

Reference: IES TM-21-11, Arrhenius model for semiconductor degradation mechanisms (non-thermal overstress).

Why Junction Temperature Matters

Junction temperature (Tj) is the most critical factor affecting LED lifespan. Each 10°C increase can reduce lifetime by approximately 30–50% depending on activation energy. High Tj accelerates crystal defects, ohmic contact degradation, and phosphor thermal quenching. By controlling thermal path (PCB, heatsink, airflow), designers directly extend LED fixture reliability. This tool empowers lighting engineers to quantify trade-offs between compact design and long life.

Step-by-step Usage

  1. Input reference L70 life from manufacturer's LM‑80 report (e.g., 50,000 hrs at 85°C).
  2. Enter reference temperature matching the test condition (typical 55°C, 85°C, or 105°C).
  3. Provide actual junction temperature – from thermal simulation or measurement (Tj = Tambient + RθJA × Power).
  4. Activation energy defaults to 0.5 eV (InGaN LED chip); for AlGaInP red LEDs use ~0.3–0.4 eV.
  5. Get estimated lifetime, acceleration factor, and thermal recommendation.

? How to Derive Activation Energy from an LM‑80 Report

Most quality LM‑80 reports include testing at three different case temperatures (e.g., 55°C, 85°C, 105°C). To extract Ea:

  1. Collect lumen maintenance data at each temperature after the same duration (e.g., 6000h).
  2. For each temperature, compute the time to reach L70 (or use TM‑21 extrapolated L70).
  3. Plot ln(L70) vs. 1/T (in Kelvin) – the slope equals Ea / kB.
  4. Solve: Ea = slope × kB. Typical InGaN yields 0.45–0.55 eV.

If the report does not provide Ea, use 0.5 eV as a conservative default. For critical designs, contact the manufacturer for the specific value.

Engineering Case Study

Outdoor Streetlight Design

A lighting manufacturer uses a COB LED with LM‑80 data: 60,000 hours L70 at Tref = 85°C. The luminaire operates in hot climate (ambient 40°C) with junction temperature reaching 95°C. Without heatsink optimization, predicted lifetime drops to 28,000 hours – below warranty requirement. By improving thermal management (adding fins and thermal interface material), Tj reduces to 75°C, raising predicted life to 52,000 hours, exceeding 5‑year operation (43,800 hrs). The calculator reproduces this decision instantly.

Limitations & Industry Standards

  • This model assumes failure mechanism dominated by temperature‑accelerated degradation (typical for LED lumen depreciation).
  • Other factors like humidity, current density, and on‑off cycles also affect life; refer to IES TM‑21 for extrapolation limits (6× LM‑80 test duration).
  • For L70 prediction beyond 6× test hours, consult manufacturer's TM‑21 report.
  • Activation energy varies with chip technology; consult LED datasheet or use 0.5 eV as a conservative industry value.
  • The L50 approximation (×1.5) is empirical; actual ratio depends on degradation curvature. For precise L50, request TM‑21 extrapolation for 50% maintenance.

Frequently Asked Questions

L70 is time until luminous flux reaches 70% of initial value (common for general lighting). L50 corresponds to 50% maintenance, often used for long-life or industrial applications. The calculator estimates L50 as 1.5× L70 as a rough empirical relation, but precise ratio depends on LED type.

Arrhenius is the most accepted industry model for temperature‑accelerated degradation of semiconductor light sources. Many LM‑80 reports provide activation energy derived from testing three temperatures, achieving high correlation (R² > 0.9).

Absolutely. Horticulture LEDs often operate at higher current and temperature. Use measured junction temperature and adjust activation energy according to the specific chip (blue/red).

Check manufacturer's LM‑80 test report, or use typical values: 0.5 eV for InGaN (blue/white), 0.35 eV for AlInGaP (red/amber). Contact supplier if uncertain.
References: IES TM-21-11, DOE LM-80, Arrhenius equation fundamentals, Philips Lumileds “Lifetime and Reliability” whitepaper (2022).