To calculate what size of compressor you need depends on what you intend to use it for. If you are planning to use the air compressor for nailing and stapling this calculator will help in determining the size you require for the job.

If you look at your owner's manual of the nailer or stapler it will tell you how much cfm delivered at a certain psi is required for proper functioning of your air tool.

Example: Operating pressure = 90 psi. Amount of air needed per cycle 0.88 cfm. One cycle occurs each time you pull the trigger.

If you intended to shoot one nail at a time and enjoy multiple coffee breaks, with these specs, you should technically be able to do this with a compressor rated at 1.2 cfm @ 90 psi, assuming that the motor is strong enough. Compressors come with a duty cycle expressed in a percentage of time that the motor can run. If it has a duty cycle of 60% then in a period of 10 minutes you would be able to let the motor run for 6 minutes. It would need to cool down for at least 4 minutes in this period. If you over use it to much you more than likely will need to purchase a new compressor in a matter of days. But if you are happy with shooting 6 nails every 10mins.........

Example Calculation:

Using two tools at the same time
Framing Nailer 3 1/2" requires 0.088 cfm per cycle @ 100 psi
Wide Crown Stapler 1"-2" x 16-Gauge requires 0.033 cfm per cycle @ 90 psi
Both tools will be operating @ the highest needed pressure, in this case 100 psi

If you don't have the specs for air consumption at a different psi divide the known amount by the given psi and multiply this amount by the psi you will be using. 0.033 / 90 * 100 = 0.03666666

Round this amount to the same amount of digits as the original and then the stapler will require 0.037 cfm @ 100 psi. This will give you a reasonable amount required.

Average framing nailer usage = 30 times a min
0.088 * 30 = 2.64 times 1.2 safety factor = 3.168 cfm @ 100 psi
Average stapler usage = 60 times a min
0.037 * 50 * 1.2 = 2.22 cfm @ 100 psi

Add both of them together and the result would be that you require a compressor that can deliver a minimum of 5.4 cfm @ 100 psi. In reality you should be looking at a compressor that can deliver 6 + cfm @ 100 psi with a 50% duty cycle. This cool down period will vary depending on temperature.

The Calculation

1. Tool One
2. average number of cycles per minute
3. required cfm per cycle @ needed psi
4. Tool Two
5. number of cycles per minute
6. required cfm per cycle @ 90 psi

The Results

1. cfm's required for tool one
2. cfm's required for tool two
3. total minimum amount cfm's required @ needed psi