Choked Gas Flow Calculator
Calculate ideal sonic-throat gas mass flow and the critical downstream pressure for an entered stagnation state.
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
Evaluate ideal maximum one-dimensional nozzle mass flux at Mach one using stagnation pressure and temperature.
ṁ=Cd A P0 √(γ/(R T0)) [2/(γ+1)]^((γ+1)/(2(γ−1)))
Worked example
Critical throat static pressure ratio for γ=1.4 is (2/2.4)^3.5≈0.528281788. Choked flow is proportional to throat area and upstream absolute pressure.
Assumptions and input details
Calorically perfect ideal gas, adiabatic isentropic approach, supplied Cd and downstream pressure low enough to choke. The tool does not check an actual downstream pressure, predict unchoked flow, or establish valve/pipe flow or safe operation.
References: NASA Glenn: mass-flow choking
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
Choose from 23 length definitions, including explicitly labelled regional measures. Area conversions square the length factor; geometric volumes cube it.
Regional measures are not interchangeable merely because their names look similar. This is a documented selection, not a claim to include every historical unit.
NIST measurement tables · Japanese traditional units · Mainland China and Hong Kong unit distinctions
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.
Solve pressure, volume, amount of gas or absolute temperature using PV=nRT. Select explicit units and inspect the substituted equation and equivalent quantities.
Calculate incompressible discharge through a small orifice using entered differential pressure and discharge coefficient.
Solve both subsonic and supersonic isentropic Mach branches for an entered area-to-sonic-area ratio.
Reserved advertising space.