Choosing A Small Air Compressor
We sorted through the specs, tried them out and found all of the factors you should check when buying a small air compressor.
Which small compressor is best?
Small air compressors are not made for every job. But for the times when you just need to do a quick job and don't want to lug your full-sized compressor around, smaller air compressors are a boon. When you're shopping for a small air compressor, the first thing you'll notice is that they're plastered with specifications: 2 hp, 3 gallon, 2.8 cfm, 130 psi, 73 dB... But don't let all those specs confuse you. We'll tell you what they mean, what matters, what doesn't, and then help you choose a compressor to suit your needs.
Small air compressors are not for ‘high-demand’ tools
None of the small air compressors we tested are good partners for air-hungry tools like pneumatic wrenches, sanders or paint sprayers. For those tools, you’ll need a much larger compressor.
Tank size matters—sometimes
The compressors we chose have tanks ranging from 1 to 6 gallons. A larger tank holds more air and will allow you to use more air before the pressure drops and the motor kicks on to refill the tank. That might let you avoid stopping work while the compressor refills the tank. But remember this: when your work demands a lot of air volume, a large tank is no substitute for adequate cfm.
CFM is the key
Cfm (cubic feet per minute) tells you how fast the air compressor can supply air, and it’s usually the most important number to consider. If a tool uses air faster than the compressor can supply it, you’ll have to stop working and wait for the compressor to catch up. Every manufacturer tests its compressors at 90 psi (an average setting for a nail gun) so you can be confident that you’re comparing apples to apples when you look at cfm numbers. The compressors we tested range from 0.6 to 2.8 cfm.
Psi usually isn’t a factor
Most compressors provide enough pressure for pro tools and tasks. In that sense, the pounds per square inch (psi) isn’t much of an issue. But a higher max psi does have one real benefit: It allows a smaller tank to hold more air and perform like a bigger tank. A 2-gallon tank at 150 psi, for example, holds as much air as a 3-gallon tank at 100 psi.
Some are four times as loud as others
The small air compressors we chose range from 60 to 87 decibels. That may not seem like a huge difference, but it is. The decibel scale isn’t like most scales you’re used to. Going up 10 dB doubles the level of noise. A machine rated at 70 dB, for example, is twice as loud as one rated at 60 dB. An 80-dB machine is four times as loud. So keep in mind that a small reduction in decibels will go a long way in making a machine more pleasant to operate.
Portability isn’t just about weight
Weight isn’t the only factor in determining whether a compressor is easy to carry- shape matters a lot. A slim small air compressor unit is the easiest to tote; wide ones are the most awkward.
Enough power for nailers?
All of the small air compressors we tried deliver enough pressure (psi) and volume (cfm) for trim nailers.
Framing nailers are another story. All of the compressors except one (Central Pneumatic 95275) provide enough pressure for framing nailers (typically about 120 psi). But only the ones with ratings of about 2 cfm or higher will keep up with a framing nailer when you’re working at moderate speed. Those with lower cfm ratings will require patience; you’ll drive a few nails, then wait for the small compressor to catch up.
Shrouding prevents damage
One of the benefits of a small compressor is that you can take it virtually anywhere. The downside is that a small air compressor is more likely to get battered and damaged. The tank will be fine, but the gauges and outlets are vulnerable unless they’re protected. Some of the compressors we tested go all in, in that they’re built with a case that surrounds the entire machine. Others leave some parts unprotected.
Other features to look for:
- Ball valve drain. Water that condenses in a compressor’s tank leads to rusting and pinhole leaks. To prevent this, manufacturers recommend that you drain the tank regularly. All tanks have drains, but there are two different types. The simplest is a drain cock, which is awkward to use, and you may even need a pliers. We prefer a ball valve drain, which works like a faucet.
- Cord wrap. Most compressors provide a convenient way to wrap up the power cord for easy carrying.
- Two outlets. Most compressors have a single outlet for connecting an air hose, but a few have two, which lets you and a buddy work together.
- Kits and accessories. For extra value, look for compressors that come with a hose or a set of inflation accessories. Some may be bundled with a nail gun and hose under a different model number.
Josh Risberg, our resident tool guru, got his hands on RIDGID's 18-volt Cordless Compressor. Here's what he had to say about this product after a couple months of use:
"When I first fired up the new RIDGID cordless compressor, I was a little put off by the noise. It’s not louder than most compressors, but I’ve gotten used to my super quiet California. But that minor inconvenience was completely forgotten once I started using it. It’s super easy to carry around to different locations throughout the shop and jobsite. I’ve even rescued a couple coworkers with flat tires by running it out to the parking lot.
Any time you go cordless, though, you have to worry about battery life. Rigid claims that these compressors will fire 1,200 brad nails per battery charge. I don’t know about that, but I’ve been using it for smaller projects a few times a week for at least a couple months without needing a recharge." -Josh Risberg, Tool and Product Editor