None of the 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.
Cfm (cubic feet per minute) tells you how fast the 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.
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.
Most compressors provide plenty of pressure for DIY 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.
The 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 a small reduction in decibels goes a long way in making a machine more pleasant to operate.
All of the 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 compressor to catch up.
Almost all small compressors are now “oil-less,” which means you never have to worry about checking or changing oil. Oil-less compressors generally wear out faster than oil-lubricated models, but that’s not likely to be an issue with normal DIY use.
To get the best read on the amount of air power a compressor can deliver, look at its cfm, not its horsepower.
One of the benefits of a small compressor is that you can take it virtually anywhere. The downside is that it’s likely to get battered. The tank will be fine, but the gauges and outlets are vulnerable unless they’re protected. Some of the machines we tested go all in: 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.
This model can be stored upright or flat; either way, its gauges and outlet are well protected. Light and easy to carry, it includes inflation accessories and an inflation hose pre-connected to a second outlet.
specs: $125 | 1.8 cfm | 19.6 lbs. | 73 dB | 1.2-gal. tank | 135 max psi | Cord wrap | Ball valve drain | 2 outlets
By far the quietest machine we tested, this unit features a corrosion-resistant aluminum tank. This model is also the most expensive in our group, but the manufacturer claims its motor will last six times longer than that of similar models. The gauges and outlet aren’t shrouded.
specs: $260 | 2.2 cfm | 35 lbs. | 60 dB | 2-gal. tank | 120 max psi | Ball valve drain | 2 outlets
We began with a couple dozen models, then narrowed the field to these eight. Each has at least one trait that makes it worth considering, whether you’re looking for power, weight, low noise or just a good deal on a good compressor.
If you can afford to spend about $300, you can get a portable compressor that'll power most DIY air tools and last for a couple of decades (see Photo 2). Look for a compressor with a cast iron cylinder, oil lubrication and air output of at least 4 cu. ft. per minute (cfm). You'll have to change the oil on schedule to keep it humming. But the longer life outweighs the hassle. Also be aware that oil-lubricated compressors inject a fine oil mist into the air line. So you'll need to invest in a separate hose and a filter if you're going to use a paint sprayer.
You can find less expensive, oilless compressors ($129 to $199) that will put out 4 cfm, but don't expect them to last as long. And you'll need to wear hearing protection—they're LOUD!
A compressor rated for 4 CFM will run all of the above tools plus lower CFM tools.
If you're a serious motorhead, you'll have to take a larger leap. If you want to run “air-motor” powered tools like impact wrenches and ratchets, you'll have to get serious with a unit that's capable of at least 5.5 cfm with a sizable air tank. Just forget about running air-powered sanders and sandblasters—those guys require almost 9 cfm. Expect to spend $540 plus for a good one. But the only thing that makes them portable is the wheels. They're heavy and bulky.