Air compressor sizing chart
Matched to the work rather than to the tool count. The jobs are ordered by how hard they are on a compressor, which is not the same as how hard they are on you.
Check which CFM a listing is quoting. Displacement CFM is the theoretical swept volume of the pump, and a single-stage compressor delivers only about 70 percent of it. A machine advertised at 7.3 CFM displacement is the same machine as one honestly rated 5.1 SCFM at 90 PSI. How to tell them apart.
By job
| Job | Sustained CFM | With margin | Compressor | Tank |
|---|---|---|---|---|
| Trim and brad nailing | 0.0 | 0.0 | 2.6 SCFM | 6 gal |
| Framing | 0.1 | 0.1 | 2.6 SCFM | 20 gal |
| Tyres and blowing down | 0.6 | 0.8 | 2.6 SCFM | 20 gal |
| General automotive | 1.7 | 2.1 | 2.6 SCFM | 30 gal |
| Cutting and grinding | 9.0 | 11.7 | 14 SCFM | 60 gal |
| Bodywork sanding | 11.0 | 14.3 | 17.5 SCFM | 60 gal |
| Spray painting, HVLP | 9.0 | 11.7 | 14 SCFM | 60 gal |
| Sandblasting | 12.0 | 15.6 | 17.5 SCFM | 80 gal |
Tank sizes are conventional pairings rather than calculated minimums: a small tank with an adequate pump works, it simply cycles more often.
What each machine can sustain
| SCFM at 90 PSI | At 40 PSI | Sustains |
|---|---|---|
| 2.6 | 5.0 | 8 of 14 tools, up to impact wrench, 1/2 in |
| 3.5 | 6.7 | 8 of 14 tools, up to impact wrench, 1/2 in |
| 4.0 | 7.7 | 8 of 14 tools, up to impact wrench, 1/2 in |
| 5.1 | 9.8 | 8 of 14 tools, up to impact wrench, 1/2 in |
| 6.4 | 12.3 | 9 of 14 tools, up to impact wrench, 1/2 in |
| 7.8 | 14.9 | 10 of 14 tools, up to die grinder |
| 10.5 | 20.1 | 11 of 14 tools, up to random orbital sander |
| 14.0 | 26.8 | 12 of 14 tools, up to hvlp spray gun |
| 17.5 | 33.5 | 14 of 14 tools, up to sandblaster, small |
| 24.0 | 45.9 | 14 of 14 tools, up to sandblaster, small |
Frequently asked questions
What size air compressor for a home garage?
For tyres, blowing down and occasional impact work, a small machine around 3.5 to 5.1 SCFM with a 20 to 30 gallon tank is ample. The moment sanding or grinding enters the picture the requirement roughly triples, because those tools run continuously.
What size compressor do I need for sandblasting?
More than most home compressors provide. Even a small blaster draws around 12 CFM continuously, which with margin is about 15.6 SCFM. Blasting is the most demanding common use of compressed air.
Can a small compressor run a spray gun?
An HVLP gun draws about 9 CFM but at 40 PSI rather than 90, and a compressor delivers more air at lower pressure. It is still a continuous draw, so it needs a machine that can sustain it rather than a large tank.