Compressor Power Estimator
Estimate the ideal and shaft power a gas compressor needs from inlet flow, inlet pressure, pressure ratio and efficiency, using isentropic or isothermal compression, with optional motor input power.
Input
Volumetric flow measured at inlet (suction) conditions.
Absolute discharge pressure divided by absolute inlet pressure.
Isentropic (or isothermal) efficiency of the compressor stage.
Output
| Property | Value |
|---|---|
| No data yet | |
More ways to use this tool
REST API
curl -X POST https://api.iotools.cloud/v1/tool/compressor-power-estimator \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"flowRate": "10",
"flowUnit": "m3min",
"inletPressure": "101.325",
"pressureUnit": "kpa",
"pressureRatio": "8",
"process": "isentropic",
"gas": "air",
"efficiency": "75"
}'Swap in your own key from your account. The tool's fields are the body — no wrapper.
Ask an AI agent
Use the IOTools `compressor-power-estimator` tool (Compressor Power Estimator) on this input:
YOUR_INPUT_HEREPaste this at any agent connected to the IOTools MCP server, then add your input.
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| Cost per API/MCP call | From 5 credits |
|---|---|
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Guides
Sizing a compressor motor starts with one question: how much power does it take to squeeze a given volume of gas up to a higher pressure? This calculator gives the ideal compression power, the shaft power once the compressor's own efficiency is included, and — optionally — the electrical input to the motor.
The formulas
With inlet absolute pressure p1, inlet volumetric flow Q1 (at suction conditions), pressure ratio r and heat capacity ratio k:
Isentropic power = k/(k−1) × p1 × Q1 × (r^((k−1)/k) − 1)
Isothermal power = p1 × Q1 × ln(r)
Shaft power = ideal power ÷ compressor efficiency
Motor input = shaft power ÷ motor efficiency (optional)Isentropic (adiabatic) is the conservative case for an uncooled single stage. Isothermal is the theoretical minimum, approached by multi-stage compression with ideal intercooling.
Worked example: 10 m³/min of air from atmospheric pressure (101.325 kPa) to 8× that, at 75% efficiency, needs about 48 kW of ideal isentropic power and 64 kW at the shaft.
How to use it
- Enter the inlet flow and unit. Use the flow at suction conditions, not "free air" at standard conditions.
- Enter the absolute inlet pressure (add atmospheric pressure to any gauge reading).
- Enter the pressure ratio — absolute discharge pressure divided by absolute inlet pressure.
- Pick isentropic or isothermal, then a gas (or a custom k).
- Enter compressor efficiency and, if you want the electrical draw, motor efficiency.
FAQ
Is this a substitute for a manufacturer's data sheet? No. It is a preliminary sizing estimate for ideal gases; real compressors have leakage, mechanical and cooling losses, and real-gas effects at high pressure.
Why must pressures be absolute?
The ratio r compares absolute pressures. Using gauge pressure understates the ratio and the power.
What efficiency should I use? Typical isentropic efficiency is 70–85% for reciprocating and screw machines and 75–88% for centrifugal units.