Blackbody Radiation Calculator

Wien's law states that the peak wavelength of blackbody emission is inversely proportional to temperature: λ_max = b/T, where b ≈ 2.898×10⁻³ m·K. Hotter objects peak at shorter wavelengths — the Sun (5778 K) peaks at ~502 nm (green), while humans (310 K) peak at ~9.35 μm (infrared).

The total power radiated per unit area is proportional to the fourth power of temperature: P/A = εσT⁴, where σ ≈ 5.67×10⁻⁸ W/(m²·K⁴) and ε is emissivity (1 for a perfect blackbody). Doubling temperature increases radiated power by 16×.

A blackbody is an idealized object that absorbs all incident radiation and re-emits it in a characteristic spectrum determined only by its temperature. Real objects approximate blackbodies — stars, furnaces, and even the cosmic microwave background (2.725 K) follow blackbody curves closely.