Free · Physics models
Gray Surface Radiated Power
Estimate total outgoing thermal radiation from area, emissivity and absolute temperature.
- Formula & worked example
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Calculator inputs
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How to use this calculator
- Enter the known values in the units shown. Results update as you type.
- Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
- Use the worked example to check the method. Reset restores the starting fields.
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Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.
Formula and method
Radiated power = 459.29973. The worked example lists its inputs and unit conventions.
P = εσAT⁴; retained σ = 5.670367×10⁻⁸ W m⁻² K⁻⁴.
Worked example
Enter these known values and leave the other values blank.
- Area
- 1 m²
- Temperature
- 26.85 °C
- Emissivity
- 1
- Radiated power
- 459.3 W
Assumptions and limitations
- This calculates outgoing emission, not net heat exchange with surroundings. A uniform gray surface is assumed. The retained radiation constant is a historical rounded value; results are model estimates rather than current precision metrology.
- Clear the quantity to solve an inverse; keep known quantities fixed with locks. Some inverses are singular or ambiguous and require further known values.
- Unit selectors convert the same physical quantity. Rounded reference constants and presets limit physical accuracy even when arithmetic displays more digits.
Common questions
What does this model assume?
This calculates outgoing emission, not net heat exchange with surroundings. A uniform gray surface is assumed. The retained radiation constant is a historical rounded value; results are model estimates rather than current precision metrology.
Can I solve for an input?
Editable calculated fields support the captured inverse relationships. Clear the unknown and supply enough independent known values; an inverse must remain within the declared physical domain.
References
This calculates outgoing emission, not net heat exchange with surroundings. A uniform gray surface is assumed. The retained radiation constant is a historical rounded value; results are model estimates rather than current precision metrology.