Wien's displacement law calculator
Enter the temperature in kelvin or Celsius to find the peak of its radiation. Used to estimate star temperatures and in thermal imaging.
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How to use it
- Enter temperature and temperature unit.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
λmax = b / T, where b = 2.897771955 × 10⁻³ m·K is Wien's constant and T is the absolute temperature in kelvin.
Example
Inputs: Temperature = 5,778, Temperature unit = kelvin (K). Result: Peak wavelength: 501.518 nm; In micrometers: 0.50152 µm; Temperature in kelvin: 5,778 K.
Limits and caveats
- It is exact for an ideal black body; real objects approach it to varying degrees.
- The peak of the spectrum per unit frequency falls at a different wavelength, so do not convert this result straight to frequency.
Questions about this tool
Why do some stars look blue and others red?
Hotter stars peak at shorter wavelengths and look bluer; cooler ones peak longer and look redder.
Where does the human body radiate most?
Near 9.3 µm in the infrared, which is why thermal cameras work in that range.
Is Wien's constant exact?
It is derived from the exactly defined Planck constant, Boltzmann constant and speed of light, and we compute it from them.