How do you calculate compressor demand?

Divide total free air consumed by the runtime to get average demand, then multiply by the compressor's efficiency to get effective delivered air. With 1200 units over 8 hours you get 150 raw, and at 90% efficiency 135 units effective.

What is a good compressor efficiency?

Modern rotary screw compressors run around 85-92% volumetric efficiency, with specific power near 18-22 kW per 100 CFM. The 90% default sits in the healthy band; a measured value well below it suggests worn elements or slipping drives.

Why is my compressor running more than expected?

The most common cause is leaks, which can waste 20-30% of generated air in an untuned plant. If raw demand far exceeds what the tools should draw, audit fittings and quick-disconnects before buying a bigger machine.

Raw vs effective compressor demand — what is the difference?

Raw demand is the simple consumption-over-runtime average (150 here). Effective demand applies efficiency losses to show what is actually delivered usefully (135), which is the number you size real capacity against.

How do I right-size a compressor from this number?

Take the effective demand, add headroom for peaks and future tools (often 25-30%), and confirm the candidate compressor's CFM at your working pressure covers it with margin for duty cycle.

Hydraulic, Pneumatic & Fluid Power Systems calculator

Compressor Demand Calculator

Compressor demand converts total compressed-air consumption over a period into an average flow rate, then derates it by compressor efficiency to give the effective delivered air. Plant engineers and pneumatics specialists use it to right-size compressors, spot leak-driven over-demand, and verify a unit is keeping up with the tools on the floor. Compressed air is one of the most expensive utilities per delivered horsepower, so understanding real versus rated demand directly affects energy cost. A mismatch between raw and effective demand often points straight at leaks or an undersized machine.

What this calculator does

Calculate compressor demand for hydraulic, pneumatic & fluid power systems planning, quoting, troubleshooting, capacity review, or process improvement.
Use it when compressor demand in hydraulic, pneumatic and fluid power systems is being committed and you need a throughput number you can defend.
It divides total air consumed by runtime to get raw throughput, then multiplies by efficiency to give effective compressor demand.

Formula used

Raw compressor demand = completed output ÷ runtime
Effective compressor demand = raw throughput × efficiency

Inputs explained

Total compressed air consumed (free air):
Compressor runtime this period:
Compressor isentropic/volumetric efficiency:

How to use the result

Use it after metering a shift's air consumption to check whether your installed compressor capacity matches real demand.
It assumes a single average flow and one efficiency value, so it will not capture peak transient demand, duty-cycle swings, or pressure-dependent compressor maps.

Current U.S. benchmarks

The U.S. has 21,668 machinery manufacturing establishments employing about 1,086,146 workers (Census County Business Patterns, 2023).

Common questions

How do you calculate compressor demand? Divide total free air consumed by the runtime to get average demand, then multiply by the compressor's efficiency to get effective delivered air. With 1200 units over 8 hours you get 150 raw, and at 90% efficiency 135 units effective.
What is a good compressor efficiency? Modern rotary screw compressors run around 85-92% volumetric efficiency, with specific power near 18-22 kW per 100 CFM. The 90% default sits in the healthy band; a measured value well below it suggests worn elements or slipping drives.
Why is my compressor running more than expected? The most common cause is leaks, which can waste 20-30% of generated air in an untuned plant. If raw demand far exceeds what the tools should draw, audit fittings and quick-disconnects before buying a bigger machine.
Raw vs effective compressor demand — what is the difference? Raw demand is the simple consumption-over-runtime average (150 here). Effective demand applies efficiency losses to show what is actually delivered usefully (135), which is the number you size real capacity against.
How do I right-size a compressor from this number? Take the effective demand, add headroom for peaks and future tools (often 25-30%), and confirm the candidate compressor's CFM at your working pressure covers it with margin for duty cycle.

Last reviewed 2026-05-12.