Wien's Displacement Law Calculator (Peak Wavelength)
Wien's displacement law links a blackbody's temperature to the wavelength at which it radiates most strongly.
K
nm
Spectral band: Visible light
- 1
Apply Wien's law: b ÷ T
2.898 × 10⁻³ ÷ 5,778 K = 0.5015 µmb = 2.897771955 × 10⁻³ m·K is Wien's displacement constant. - 2
Convert to nanometres: λ_µm × 1000
0.5015 µm × 1000 = 501.52
How does this calculator work?
Wien's displacement law states the peak emission wavelength of a blackbody equals Wien's constant b (2.8978×10⁻³ m·K) divided by its temperature in kelvin. Enter a temperature to get the peak wavelength, or a wavelength to get the temperature, plus the matching spectral band.
Formula
How this is calculated
Enter a temperature T in kelvin and the calculator returns the peak wavelength λ_peak using Wien's displacement law, λ_peak = b / T, where b = 2.897771955×10⁻³ m·K is Wien's constant. Alternatively, leave T blank and supply a peak wavelength (in nanometres) to invert the relation and solve for the temperature, T = b / λ. Temperature takes priority when both fields are filled.
The result is reported in nanometres and micrometres, and the corresponding peak frequency is computed from f = c / λ using the speed of light c = 2.99792458×10⁸ m/s. The wavelength is also classified into a region of the electromagnetic spectrum — radio, infrared, visible, ultraviolet, X-ray, or gamma ray — using standard band boundaries (visible light spans roughly 400–700 nm).
The law assumes an ideal blackbody in thermal equilibrium. The plotted curve is the Planck spectral radiance B(λ,T) = (2hc²/λ⁵)/(exp(hc/λkT) − 1), normalised to its maximum, which illustrates why the emission peaks at λ_peak. Inputs must be positive; non-positive or empty values produce no result.
Frequently asked questions
Using the Sun's effective temperature of about 5778 K, Wien's law gives λ_peak ≈ 501 nm, in the green part of the visible spectrum.
No. A blackbody emits across the whole spectrum; Wien's law only identifies the single wavelength of maximum spectral radiance. The full distribution follows Planck's law.
Because λ_peak is inversely proportional to temperature, higher temperatures shift the peak toward shorter (bluer) wavelengths, while cooler objects peak in the red or infrared.
Also known as
TG we-Calculate Editorial Team. (2026). Wien's Displacement Law Calculator (Peak Wavelength) [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/wien-displacement-law-calculator
TG we-Calculate Editorial Team. "Wien's Displacement Law Calculator (Peak Wavelength)." TG we-Calculate. 2026. https://we-calculate.com/calculator/wien-displacement-law-calculator.
TG we-Calculate Editorial Team, "Wien's Displacement Law Calculator (Peak Wavelength)," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/wien-displacement-law-calculator
@misc{wecalculate_wien_displacement_law_calculator, title = {Wien's Displacement Law Calculator (Peak Wavelength)}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/wien-displacement-law-calculator}}, year = {2026}, note = {TG we-Calculate} }
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