MAXScanner engineering calculator
Choked Flow Calculator — Gas Mass Flow & Critical Pressure
Calculate maximum ideal-gas mass flow through a nozzle or orifice and check whether the entered downstream pressure is low enough to choke the flow.
Last updated: September 17, 2026
Results
Formula, example and assumptions
P*/P0=(2/(γ+1))^(γ/(γ−1)); ṁ=Cd·A·P0·sqrt(γ/(R·T0))·(2/(γ+1))^((γ+1)/(2(γ−1))).
Air at 500 kPa abs and 300 K through 20 mm² with Cd=0.9 gives about 0.021 kg/s maximum choked flow.
- Calorically perfect ideal gas with constant γ and R.
- Upstream pressure and temperature are stagnation values; downstream pressure only determines whether choking is possible.
Frequently asked questions
What does this Choked Flow Calculator solve?
Calculate maximum ideal-gas mass flow through a nozzle or orifice and check whether the entered downstream pressure is low enough to choke the flow.
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.