Surface Radiation Heat Exchange Calculator
Estimate signed net radiation between an entered gray surface and a large uniform surrounding enclosure.
YOUR CALCULATION
Result
—
Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Convert temperatures to kelvins and apply Stefan–Boltzmann emission and absorption for a surface fully surrounded by a uniform black enclosure. Subtract absorbed from emitted power.
Net outward power=emissivity×σ×area×(Tsurface⁴−Tsurroundings⁴)
Worked example
At surface 400 K, environment 300 K, area 1 m² and emissivity 1, net outward radiation is about 992.3155 W. Equal temperatures give zero net transfer.
Assumptions and input details
Diffuse gray surface in a large uniform black enclosure, view factor one and equal absorptivity/emissivity. Used σ=5.670374419×10^−8 W/(m² K⁴), a rounded SI value. Negative net power means radiative energy gain. Excludes finite two-gray-surface resistance, convection, conduction, solar loading and temperature evolution. This does not predict cooling time.
References: OpenStax: Stefan–Boltzmann net radiation model
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
Calculate steady conductive heat flow through layers in series. Inspect thermal resistance, heat flux, transferred energy and interface temperatures.
Calculate log mean temperature difference and ideal duty or exchange area for entered parallel/counterflow end temperatures.
Estimate straight circular-pipe and entered minor losses with an explicit Darcy friction factor convention.
Reserved advertising space.