LED PCB Thermal Calculator

For LED PCB & component manufacturers — board temperature rise, effective thermal resistance, and junction estimate for LED boards (MCPCB / FR4).

Heat source
Board & environment
FR4 ≈ 0.3 · Al-core ≈ 1–8
Board area
– cm²
Heat on board
– W
Rth conduction
– °C/W
Rth convection
– °C/W
Rth total
– °C/W
ΔT rise
– °C
Board temp
– °C
Est. Tj per LED
– °C
P = n·Vf·If·(1−η) · Rthcond = t/(k·A) · Rthconv = 1/(h·A) · ΔT = P·Rthtotal · Tpcb = Ta + ΔT · Tj ≈ Tpcb + (P/n)·Rthjb (in-plane spreading & copper planes improve real performance).