Stefan-Boltzmann Thermal Radiation Calculator
The Stefan-Boltzmann Law states that total electromagnetic thermal power P radiated across all wavelengths by a body of surface area A and emissivity ε scales with the fourth power of absolute temperature T.
Total radiant heat flux emitted in Watts
Dimensionless radiative efficiency (1.0 = ideal blackbody)
Exposed surface area in m²
Surface temperature in Kelvin
Step-by-Step Calculation
The Stefan-Boltzmann Law states that total electromagnetic thermal power P radiated across all wavelengths by a body of surface area A and emissivity ε scales with the fourth power of absolute temperature T.
Real-World Reference Values
Fundamental physical radiation constant
High infrared radiative cooling surface
Spacecraft MLI thermal blanket reflector
20-Row Comparison Table
Radiated Thermal Power (P) · Surface Emissivity (ε)
| # | Surface Emissivity (ε) | Radiated Thermal Power (W) | Δ % |
|---|---|---|---|
| 01 | 0.333 | 305.894 W | -63.00% |
| 02 | 0.394421 | 362.3154 W | -56.18% |
| 03 | 0.455842 | 418.7369 W | -49.35% |
| 04 | 0.517263 | 475.1583 W | -42.53% |
| 05 | 0.578684 | 531.5797 W | -35.70% |
| 06 | 0.640105 | 588.0011 W | -28.88% |
| 07 | 0.701526 | 644.4225 W | -22.05% |
| 08 | 0.762947 | 700.844 W | -15.23% |
| 09 | 0.824368 | 757.2654 W | -8.40% |
| 10 | 0.9 Current | 826.7406 W | 0.00% |
| 11 | 0.947211 | 870.1082 W | +5.25% |
| 12 | 1.0086 | 926.5296 W | +12.07% |
| 13 | 1.0701 | 982.951 W | +18.89% |
| 14 | 1.1315 | 1,039.37 W | +25.72% |
| 15 | 1.1929 | 1,095.79 W | +32.54% |
| 16 | 1.2543 | 1,152.22 W | +39.37% |
| 17 | 1.3157 | 1,208.64 W | +46.19% |
| 18 | 1.3772 | 1,265.06 W | +53.02% |
| 19 | 1.4386 | 1,321.48 W | +59.84% |
| 20 | 1.5 | 1,377.90 W | +66.67% |
Frequently Asked Questions
Why does doubling absolute temperature T multiply radiated power by 16×?+
Because radiant flux scales with T⁴ (2⁴ = 16), thermal radiation dominates heat transfer at high temperatures and in vacuum.
How do I calculate spacecraft radiator area needed in vacuum?+
Click SOLVE FOR on A (Radiating Surface Area), enter waste heat load P, coating emissivity ε, and maximum operating temperature T.
What is a graybody vs a blackbody?+
An ideal blackbody has ε = 1.00 and absorbs/emits 100% of thermal radiation; real materials (graybodies) have 0 < ε < 1.