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Air Compressor Size Calculator

Select your air tools and usage pattern — get the minimum CFM at 90 PSI, the right tank size, and a matched compressor recommendation for your garage setup.

CFM @ 90 PSI Tank Size No Sign-Up Required
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HomeWorkshopGuide Editorial Team Editorial Research · About our process
Quick Answer

For most home garage shops running nailers and inflation tasks, a 6-gallon pancake compressor producing 2.5 to 4 CFM at 90 PSI is sufficient. Add impact wrenches or orbital sanders and you need 5 to 8 CFM. Spray guns and dual-action sanders require 10 to 15 CFM — at that level, a portable pancake compressor is typically inadequate. Use the calculator below to get the number for your specific tool set.

Find Your Air Compressor Size
Select Your Air Tools Add each tool you plan to use. The calculator sums the CFM requirements and applies a 25% safety buffer.
Min CFM @ 90 PSI — CFM
Tank Size — gallons
Reference

CFM Requirements by Tool Type

CFM (cubic feet per minute) at 90 PSI is the standard spec for sizing a compressor to your tools. The table below shows typical CFM demands for common garage air tools. Intermittent-use tools (nailers, wrenches) draw air in bursts — the tank refills between uses. Sustained-use tools (sanders, spray guns) draw air continuously and require higher compressor output.

ToolCFM @ 90 PSIDuty CycleNotes
Brad Nailer (18 GA)1.0IntermittentOne shot per trigger pull; tank refills between nails
Finish Nailer (15–16 GA)2.2IntermittentHigher demand than brad; allow tank recovery time
Framing Nailer4.5IntermittentHighest demand among nailers; needs adequate tank volume
Impact Wrench (1/2")4.0IntermittentBurst demand at engagement; low duty cycle in practice
Die Grinder6.0SustainedContinuous draw; undersized compressor will cycle constantly
Air Orbital Sander6.0SustainedMost demanding sustained-use tool for home shops
HVLP Spray Gun12.0SustainedRequires high-output compressor; pancake units inadequate
Blow Gun3.0IntermittentVaries by orifice size and distance

Intermittent vs Sustained Use

The distinction between intermittent and sustained tool use determines whether tank size or compressor output is the binding constraint. Nailers fire one shot and pause — the tank absorbs the burst demand and the compressor refills between shots. A 6-gallon compressor with modest CFM output handles nailers well because it never has to supply air continuously.

Sustained-use tools draw air without stopping. If the compressor's output CFM is lower than the tool's demand CFM, the tool runs lean — reduced power, poor finish quality, or the compressor running at 100% duty cycle continuously. Sustained-use tool setups require a compressor whose rated CFM output meets or exceeds the tool demand, not just a large tank.

On Amazon
Recommended Accessories
💨 BOSTITCH Pancake Compressor — 6 Gal Compact, portable, and handles nailers and inflation tasks well. The standard starting point for most home garage setups. View on Amazon → 🔧 DEWALT 6-Gallon Pancake Compressor Higher-output pancake option that handles finish nailers and moderate impact wrench use. Reliable motor recovery time. View on Amazon → ⬆️ California Air Tools Vertical Compressor Higher CFM in a vertical footprint — suitable for sanders and impact wrenches that exceed pancake compressor capacity. View on Amazon → 🔩 Wall Mount Air Compressor Permanent installation keeps the floor clear. Suited for sustained-use tool setups requiring consistent high CFM output. View on Amazon →
FAQ

Common Questions

How do I calculate what size air compressor I need?+
Add up the CFM requirements of the tools you plan to run, apply a 25% safety buffer, and match that total to a compressor rated at or above that number. For intermittent-use tools like nailers, tank size matters more than raw CFM. For sustained-use tools like sanders, CFM output is the primary constraint.
What is a good CFM for a garage air compressor?+
For nailers and inflation, 2.5 to 4 CFM at 90 PSI. Adding impact wrenches or orbital sanders requires 5 to 8 CFM. Spray guns and dual-action sanders need 10 to 15 CFM — at that level a portable pancake compressor is typically inadequate.
What tank size do I need for a garage compressor?+
For intermittent-use tools like nailers, a 6-gallon tank is adequate. For sustained-use tools like sanders and spray guns, a 15 to 20-gallon or larger tank reduces compressor cycling and maintains more consistent pressure at the tool.
Can I run multiple air tools at once with a portable compressor?+
Running multiple tools simultaneously multiplies CFM demand. A standard 6-gallon pancake compressor producing 2.5 CFM cannot sustain two tools running concurrently. Calculate the combined CFM of all tools running at once and size the compressor to that number.
What is the difference between pancake and vertical air compressors?+
Pancake compressors are highly portable with a low center of gravity, limited to about 6 gallons and 2.5 to 3 CFM output. Vertical compressors use less floor space for the same volume — a 20-gallon vertical unit has a similar footprint to a 6-gallon pancake while delivering significantly more capacity and typically higher CFM output.
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