LED Thermal & Efficiency Calculator
Calculate LED efficiency metrics and junction temperature from electrical and thermal parameters.
An LED's junction temperature is the single most important reliability and performance parameter: it controls wavelength shift, efficiency droop, and long-term lumen depreciation. The electrical power not converted to light dissipates as heat, driving the junction above ambient through a series thermal resistance chain — junction-to-solder, solder-to-board, board-to-heatsink, and heatsink-to-ambient. This calculator takes forward current and voltage to establish total electrical power, then uses either wall-plug efficiency or direct optical power to partition it into optical output and heat dissipation. The thermal model T_j = T_a + P_diss × R_θ(j-a) is evaluated against the manufacturer's maximum rated junction temperature, reporting thermal margin with pass/warn/fail status. External quantum efficiency (EQE = WPE × eV_F / hν) is computed when peak wavelength is provided. Inputs accept SI values from standard LED datasheets.