MAXScanner engineering calculator
Radiation View Factor Calculator — Facing Surface Approximation
Estimate the geometric view factor between two small directly facing surfaces and net black/gray radiant exchange for first-pass thermal checks.
Last updated: September 17, 2026
Results
Formula, example and assumptions
F12≈min[1,A2/(πd²)]; Q≈σA1F12(T1⁴−T2⁴)·εeff.
A 0.01 m² target 0.5 m away gives the small-surface estimate F12≈0.0127.
- The A2/(πd²) relation is a small-solid-angle approximation, not a finite-rectangle closed form.
- Surfaces face each other directly; use a geometry-specific method when dimensions are not small relative to spacing.
Frequently asked questions
What does this Radiation View Factor Calculator solve?
Estimate the geometric view factor between two small directly facing surfaces and net black/gray radiant exchange for first-pass thermal checks.
Which units should I use?
Use the units printed beside each input. Dimensionless ratios need no conversion; pressure inputs used in gas equations are absolute unless the field explicitly says differential.
Is this suitable for final engineering design?
Use it for transparent first-pass calculations and cross-checks. Final design should verify gas or fluid properties, geometry, loss data, equipment curves and the applicable engineering standard.