Air Compressor Unit Converter

The ones that bite

Bar is not 15 psi.

It is 14.5. The 15 shortcut is fine for a conversation and wrong by 3.5 percent on a pressure switch setting. 8 bar is 116 psi, not 120. 10 bar is 145, which is why European machines rated at 10 bar end up on 150 psi tanks here.

CFM is not SCFM is not ACFM.

Manufacturers rate pumps in free air delivered at the inlet, which is close enough to SCFM for sizing. A tool's consumption is also free air. Neither is the volume of compressed air moving through the pipe, which is smaller by the compression ratio. This converter treats CFM as free air, like every catalog you'll compare it to.

Litres per minute is the number on the air tool.

European tool specs quote l/min and they look enormous. 500 l/min is 17.7 CFM. Divide by 28.3 and move on.

Horsepower on a compressor is nameplate, not output.

A 5 HP motor draws about 4.3 kW at full load after efficiency. A "5 HP" consumer compressor with a 15 amp plug is drawing 1.8 kW and is not 5 HP by any definition we recognise. The pump-up test settles that argument in two minutes.

Gallons versus litres on the tank plate.

An 80 gallon receiver is 303 litres. A European 270 litre tank is 71 gallons. Close, not the same, and it matters when you're sizing storage against a cycle rate.

Conversions use exact factors. The air specific figures assume sea level atmosphere at 14.696 psi and the catalog median outputs from our compressor range, 3.25 CFM per HP for two stage piston and about 4.2 for rotary screw at 100 psi.