/ Resources · Sizing

How big a compressor do you need?

List the air tools and machine stations, say how often each one actually runs, and get the CFM you need, a horsepower range, and a receiver tank to match. Then send it to us as a quote request in one click.

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Size it

updates as you type

Your tools and stations

Tool or station	CFM each	How many	Use %	Remove

Use % is the share of the shift the tool is actually blowing air. Hand tools in a shop often run well under half the time; a machine that cycles all shift can be close to 100%.

Source: preset CFM values are typical ratings at 90 psig from air tool maker spec sheets. The tool's own data plate always wins. Demand = CFM x quantity x use %, the load-factor method in the US DOE / Compressed Air Challenge Sourcebook, "Improving Compressed Air System Performance".

System settings

Pressure needed (psi) Leak allowance (%) Room to grow (%)

Source: leak allowance per the DOE / Compressed Air Challenge Sourcebook leaks fact sheet: a well-kept system holds leaks under 10% of output, while many plants run 20% to 30%. Room to grow is your call, not a standard; we start at 20%.

Air you need

0CFM

Tools and stations: 0 CFM
Leak allowance: 0 CFM
Room to grow: 0 CFM
Compressor size: -
Receiver tank: -
Tank range: -

Source: HP range uses 4 to 5 CFM per HP at about 100 psig, the rule of thumb in the DOE / Compressed Air Challenge Sourcebook, rounded up to standard motor sizes. For a real machine, read its CAGI Performance Data Sheet, which lists tested CFM and kW at rated pressure. Tank range uses 3 to 5 gallons per CFM, from US DOE / ORNL Better Plants compressed air training (the old 1 gallon per CFM rule is out of date); the pick is the smallest stock tank at or above the low end. Load/unload machines want more, see receiver sizing.

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How the math works

1. Add up real demand

Each row is CFM x how many x use %. A 5 CFM impact gun that runs 30% of the time only needs 1.5 CFM on average. Adding up nameplate CFM alone oversizes the compressor.

2. Add leaks and growth

Leaks come off the top of every system, so we add them on the tool demand. Room to grow is added on top of both, so next year's new station is already covered.

3. Turn CFM into HP

A good machine makes about 4 to 5 CFM per HP at 100 psi. We show both ends of that range, rounded up to the next standard motor size.

4. Pick the tank

A receiver of 3 to 5 gallons per CFM evens out short bursts and keeps the compressor from starting and stopping too often.

Source: US DOE / Compressed Air Challenge, "Improving Compressed Air System Performance: A Sourcebook for Industry"; CAGI Performance Data Sheets; compressor maker sizing guides. This tool gives a starting size, not a system design. Pressure drop, dryers, and peak events can change the answer.

Want us to check the numbers?

Send the result as a quote request. We'll check it against your actual load, suggest a machine, tank, and dryer, and come back with pricing.

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