Wien's Displacement Law Calculator

Every object above absolute zero radiates thermal energy across a spread of wavelengths, and Wien's displacement law says that spread's peak shifts to shorter wavelengths as temperature rises: λmax = b ÷ T, where T is absolute temperature in kelvin and b is Wien's displacement constant, 2.897771955×10⁻³ m·K (a measured physical constant, not something this calculator assumes changes). The same identity rearranges to T = b ÷ λmax to go the other direction, from an observed peak wavelength back to temperature.

The default, 5778 K, is the Sun's approximate photosphere temperature, which places its emission peak at about 502 nm — squarely in the blue-green part of the visible spectrum (the Sun's light looks white overall because it emits broadly across all visible wavelengths, not just at the peak). Cooler objects, like the human body at roughly 310 K, peak in the mid-infrared, around 9,300 nm — far outside what the eye can see, which is exactly why thermal/night-vision cameras exist.