Dimensionless Numbers Calculators

Live calculators

• Reynolds Number CalculatorCompare inertia and viscosity, with an internal-flow regime interpretation.
• Prandtl Number CalculatorCompare momentum and thermal diffusion from consistent fluid properties.
• Biot Number CalculatorScreen internal versus surface thermal resistance before a lumped-capacitance analysis.
• Fourier Number CalculatorCalculate dimensionless time for a transient-conduction problem.
• Nusselt Number CalculatorSolve Nu or h, with a scope-checked turbulent-pipe correlation mode.
• Mach Number CalculatorCalculate speed relative to the local speed of sound from a known value or ideal-gas properties.
• Froude Number CalculatorScreen shallow-water and open-channel flow from mean velocity and hydraulic depth.
• Grashof Number CalculatorCompare buoyancy and viscous effects in a natural-convection screening problem.
• Rayleigh Number CalculatorCombine buoyancy, viscous and thermal-diffusion effects for natural-convection screening.

How to use these numbers

1. Start with the number that matches the physics you need to screen: flow regime, thermal diffusion, internal thermal resistance, buoyancy or compressibility.
2. Use values evaluated at a consistent reference temperature and state.
3. Only apply a heat-transfer or flow correlation after checking its geometry, regime and valid range.