Air Compressor CFM Calculator: Size a Compressor for Your Tools

Compressors are compared by horsepower and tank size, but what matters is delivered airflow at the pressure your tools need. List your air tools with their CFM at 90 PSI from each manual, mark which run together, and the calculator gives the delivery to look for.

When this tool helps most

Use it before buying a compressor, or when an existing one cannot keep up with a sander, paint gun or impact wrench.

How to use this tool

1. List each air tool and its CFM at 90 PSI from the manual.
2. Mark tools that run at the same time with 1.
3. Set a margin so the compressor does not run flat out.
4. Compare compressors by delivered CFM at 90 PSI.

Worked example

The example list has an impact wrench at 5 CFM, a brad nailer at 0.5 CFM and a tire inflator at 1 CFM, with only the impact wrench running at a time. With a 30 percent margin, look for a compressor delivering at least 6.5 CFM at 90 PSI. The example figures are placeholders; use your own tools’ ratings.

Understanding your results

Delivered CFM decides whether continuous tools keep working. Tank size smooths short bursts but does not raise delivered airflow.

Common mistakes to avoid

• Buying by horsepower or tank size alone.
• Forgetting tools that run continuously, such as sanders and paint guns.
• Using compressed air to blow dust off clothing or skin.
• Running a 240-volt compressor on an undersized circuit.

How to get the most accurate result

• Measure your own garage with a tape measure instead of using typical sizes.
• Use the numbers printed on your product labels, manuals and data sheets.
• Change one input at a time to see which assumption matters most.
• Print or save the result and bring it to your installer or contractor.

Next steps

Read choosing an air compressor for a garage.

Frequently asked questions

What size air compressor do I need for an impact wrench?

Check the wrench’s CFM at 90 PSI in its manual, then choose a compressor that delivers more than that with a margin.

Is a bigger tank better?

A bigger tank stores more air for short bursts, but delivered CFM decides whether continuous tools keep working.

Can I use compressed air to clean my workbench?

OSHA limits compressed air for cleaning in workplaces to under 30 psi with chip guarding and protective equipment. At home, use a vacuum where you can and wear eye protection.

This tool is for planning and education only. It does not store your entries. Garage door springs and cables are jobs for a trained technician, and new circuits are jobs for a licensed electrician. Read our disclaimer.