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Grashof Number Calculator — Natural Convection Gr

Calculate Grashof number from gravity, thermal expansion, temperature difference, characteristic length and kinematic viscosity; also report buoyancy-to-viscous force context.

Last updated: September 17, 2026

Results

β, length and viscosity must be positive

Formula, example and assumptions

Gr=gβΔTL³/ν².

For air with β=0.0033 1/K, ΔT=30 K, L=0.5 m and ν=1.6×10⁻⁵ m²/s, Gr≈4.74×10⁸.

  • Properties should normally be evaluated near film temperature.
  • Use the characteristic length appropriate to the geometry and correlation.

Frequently asked questions

What does the Grashof Number Calculator calculate?

Calculate Grashof number from gravity, thermal expansion, temperature difference, characteristic length and kinematic viscosity; also report buoyancy-to-viscous force context.

Which units should I use?

The input labels show the required SI units. Keep properties and geometry consistent before using the result in another engineering calculation.

Can I use this result for design?

Use it for transparent engineering estimates and checks. Validate property data, geometry, correlations and applicable codes for safety-critical design.

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