Best Air Compressors
While air compressors might not be at the top of every DIYers’ must-have list, these tools are actually very useful for a wide range of purposes. The right air compressor can do everything from inflating your car tires and pool floats to putting the “power” in your power washer to running pneumatic tools such as paint sprayers and air-driven nail guns.
There are portable air compressors and models intended to remain stationary—generally, portable models are best for homeowners or DIYers, while stationary models are better suited to professional purposes. Tank size is another important consideration, as the larger the tank, the more power the tool can provide. Still, for most DIY projects, a 4-to-6-gallon tank is sufficient.
Here are our favorite air compressors in several categories.
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What to Look for in an Air Compressor
There are two types of air compressor: stationary and portable. Stationary air compressors are larger and are designed to stay in one location, like a workshop. Portable air compressors are much more versatile and more common for residential use since they can be moved easily.
Air compressors can be powered by either gas or electricity, though electric models are more common. They require less maintenance, are quieter, and are suitable for indoor use. Gas-powered models are recommended only if you’ll be working outdoors with limited or no electricity.
Smaller 4 to 6-gallon tanks are sufficient for most household projects, while larger tanks are better suited to large-scale projects or commercial use.
What size air compressor do I need?
There are several factors involved in determining the size of the air compressor you’ll need. One is the way the tool works; tools that operate continuously, such as grinders or sanders, need an air compressor with a larger tank capacity than a tool that only operates in short bursts of power, such as a pneumatic nail gun. For most typical DIY purposes, an air compressor with a 4- to 6-gallon tank is big enough to handle most common tasks, but you could need a larger tank if you’ll be using a powerful tool for an extended period of time—for example, painting the exterior of your home.
The most important factor to consider, however, is the airflow requirements of the tools you plan on using with your air compressor. This is measured in standard cubic feet per minute (scfm). Your air compressor needs to be able to meet and surpass the airflow requirements, which can vary a great deal between different types of tool. For example, when the air compressor is set at 90 psi, the average pneumatic framing nailer or tire inflator only requires around 2 scfm to operate, while an angle grinder needs 5-8 scfm, and a random orbital sander might need more than 10 scfm.
For a rough guideline when determining how much airflow you’ll need, check the required scfm ratings of all the tools you plan on using with the air compressor. Multiply the highest scfm rating by 1.5; for example, if you’ll be using a paint sprayer that requires 5 scfm, multiply 5 by 1.5, which gives you a needed scfm of 7.5. The higher the scfm, the larger the air compressor.
Another number to consider is the pressure generated inside the air compressor, which is measured in pounds per square inch (psi). As a general rule, smaller tools, such as nailers and inflators, only require around 90 psi, while more powerful tools, such as grinders and sanders, might need as much as 150 psi to operate effectively.
How do you use an air compressor?
While the specifics can vary between different brands and models of air compressor, the following basic guidelines apply to most of them.
- Position the air compressor on flat, stable ground within reach of an electrical outlet, and plug in the power cord. Don’t turn on the air compressor yet.
- Check the oil level. Typically, the oil gauge will be near the motor. Note, however, that many newer air compressors no longer require the addition of oil, as they have sealed systems. These air compressors are often sold as “oil free.”
- If the oil level is low, add compressor oil—this oil does not have detergents or additives commonly found in automotive oil—to the oil tank until the oil level reaches the “Full” mark. The oil tank access cap is often found on the top of the air compressor.
- Make sure the drain valve is switched to the closed position. You’ll find the drain valve near the bottom of the air compressor.
- Switch the air compressor on, and let it run until it reaches the pressure capacity. For most air compressors, that will be 100 to 115 pounds per square inch (psi). The pressure gauge is normally on the top of the air compressor.
- Set the air control valve—it will be on top of the air compressor—to the recommended maximum psi of the tool you plan on using.
- Connect the air hose to your air compressor. Some models have quick-connect fittings, while others require you to screw the hose to the fitting. Make sure the hose is tightly secured. You might need to use an adjustable wrench for this.
- Connect the other end of the air hose to your pneumatic tool.
- Use your tool as needed. When finished, turn the air compressor off, disconnect the tool, and unplug the air compressor from the electrical outlet.
- Unscrew the drain valve at the bottom of the air compressor—you’ll typically need an adjustable wrench for this—and allow any accumulated moisture to drain before storing your air compressor.
How do air compressors work?
While different air compressors can have different methods of achieving the goal, all basically work by pulling outside air into a chamber, which then compresses to greatly increase the pressure of the contained air. When you attach your pneumatically powered tool to the air compressor, the compressed air is forced through the relatively tight hose fitting, through the air hose, and into your tool. It’s something like turning on a garden hose, and then using your finger to partly close off the end of the hose; the water pressure increases due to the force of the water compressed within the hose squeezing through the restricted opening.