How Big of an Air Compressor Do I Need?
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How Big of an Air Compressor Do I Need?

To use air tools such as pint guns, impact wrenches, tire inflators, you’ll need an air compressor. Therefore, your compressor should be capable of meeting the requirements of your tools by buying the right size. Size doesn’t mean the physical dimensions but the ability of the compressor to handle the work. It would be best if you consider some factors like CFM, PSI, horsepower, and more.

What Size of Compressor Do I Need?

When choosing the compressor to use, you need first to determine how you will be using it. You should also consider the storage tank’s capacity, frequency of using it, and other factors, as explained below.

Air Reservoirs

It refers to the compressor’s tank size. Regardless of having sufficient PSI and CFM, the tank size should store enough compressed air enough for efficient operation. Having a large tank keeps work flowing by holding adequate air as the compressor cycles through a recharging process.

There is a broad range of reservoir capacities from one gallon to 60-gallon tanks. For a home garage, a compressor size of the 2.6-20-gallon scale can do excellent work. But sizing your compressor depends on the type and number of air tools you intend to use. If using extensive tools, consider buying a higher reservoir gallon.

Also, choose between a horizontal and vertical tank. The choice depends on the intended location of the compressor and space available. The vertical designs have a smaller footprint and work better if you have less space.

Air Tool Types

The tool types you intend to use influence the size of the air compressor. Please make a list of the air tools you will be using, how often you’ll be using them, and the number of devices in use at a single operation. Some air tools demand a lot of CFM and PSI than others. For example, a sizeable air-driven framing or fencing nailer requires more air supply than a small wrench. A continually operating air drill demands more CFM than a single-use air stapler.

The best way to determine the right-sized compressor is by adding all the CFM requirements of all tools and identifying each peak PSI. It gives the upper limit of tank size in gallons, capacity in CFM and PSI you require. As a rule, add around 10-20 % above the anticipated limit for your air compressor’s best efficiency.

Air Flow Required

The compressors measures in two ways; PSI (pounds per square inch) and deliverable CFM ( cubic feet per minute); the measurements determine the effectiveness of the compressor in different situations. When selecting a compressor, first determine the PSI and CFM requirements of your tools. If using one device at a time, use its highest PSI and CFM, but for multiple instruments simultaneously, consider the total CFM required.

The compressor should have higher CFM and PSI airflow requirements that exceed the highest rated tool; this means it shouldn’t be underpowered. It’s advisable to purchase an air compressor with double times more CFM airflow than your devices require. The guideline ensures the compressor works efficiently without breakdown.

Table: Air Pressure Requirements for Air Tools

Tool NameCFM of each tool
Angle Disc Grinder6
Air Drill 1/24
Air Drill 3/84
Chisel/Air Hammer4
Die Grinder8
Ratchet 1/4″3
Impact Wrench 1/2″5

Horse Power

The power source needs to be adequate to run the compressor unit. Most manufactures will naturally size the horsepower to match the CFM, PSI, and gallon capacity of the compressor. But do not select air compressor by horsepower rating; pay attention to air capacity and pressure.

You might also consider the peak, brake, horsepower, which measures the maximum output a motor can generate while windings are engaged.  The peak horsepower can be as much higher as seven times than the running horsepower. Other specifications are the duty cycle and service factor.

The duty cycle will be intermittent or continuous. It explains whether a motor can run a full horsepower continuously or intermittently. In case you need maximum horsepower, choose a constant duty cycle. A motor service factor describes the rated horsepower percentage to operate safely and is higher than rated power. Machines with higher service factors run in adverse situations like low voltage or high startup without failure and tend to have a longer lifespan.

Piston Displacement and FAD

Piston displacement is theoretically what air compressor can produce directly at the cylinder. FAD stands for free air delivery; what the air compressor delivers at the outlet and is essential to you. FAD should always be smaller than piston displacement. The two come in CFM and L/Min (liters per minute).

Garage Space

Air compressors with huge tanks require a lot of space; therefore, it’s better to select an average unit if you have a small space. The bigger compressor also produces loud noise while operating, and this causes a nuisance. It’s wise to choose a compact model to avoid noise complaints from neighbors.

Again, choose a machine that fits your working conditions. For example, running gasoline may give off toxic fumes, which can harm your indoor space health. Go for an electric compressor if you want to use yours indoors. Compressors also require the right airflow to ensure proper cooling. Avoid placing your compressor in a tightly enclosed space as it reduces airflow and results in overheating issues and premature failure. Consider the open space available to match compressor size and type.

Use of Compressor

You require a compressor that fits your workload depending on your work and the daily amount of time you’ll use it. Choose a compressor that matches your duty cycle to supply the correct amount of pressure throughout the day.  A piston compressor is perfect for intermittent works such as in an automotive garage where a worker use air tools for part of the day. In this scenario, the rotary screw compressor would be too large and not an optimal choice. Rotary screw best fits applications with higher demand so that they run continuously.


Air compressors are handy machines when it comes to DIY projects, such as home repairs or renovations. Choosing a compressor is about reflecting on your needs. If you need something for emergencies only, a small air compressor that is portable, and inexpensive is perfect. But, if you’re looking to go commercial or working with too many air-powered tools, then a bigger model is essential.

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