Calculator
Formula used
Planck law (wavelength form): Bλ(T) = (2hc²/λ⁵) · 1/(e^{hc/(λkT)} - 1)
Planck law (frequency form): Bν(T) = (2hν³/c²) · 1/(e^{hν/(kT)} - 1)
Spectral exitance: Mλ = επBλ and Mν = επBν
Total exitance (Stefan-Boltzmann): M = εσT⁴, and P = MA
Peak wavelength (Wien): λmax = b/T
Units are SI. Wavelength-point results are also shown per nm.
How to use this calculator
- Enter temperature in kelvin and emissivity between 0 and 1.
- Select wavelength or frequency for a spectral point evaluation.
- Optionally add emitting area to compute total and spectral power.
- Optionally add distance to estimate far-field irradiance.
- Press Compute to see results above the form.
- Use CSV or PDF buttons to export the latest calculation.
Example data table
Sample: T = 5778 K, ε = 1, λ = 500 nm, A = 1 m², r = 1 m.
| Input | Value | Unit |
|---|---|---|
| Temperature | 5778 | K |
| Emissivity | 1 | |
| Wavelength | 500 | nm |
| Area | 1 | m^2 |
| Distance | 1 | m |
| Output | Value | Unit |
|---|---|---|
| Total exitance (M) | 6.32007e+7 | W/m^2 |
| Peak wavelength | 501.518 | nm |
| Mλ at 500 nm | 82861.6 | W/m^2/nm |
| Total power (A=1) | 6.32007e+7 | W |
| Far-field irradiance (r=1, approx.) | 5.02935e+6 | W/m^2 |