If you need an air compressor for commercial or industrial use, like construction or transportation maintenance, determining what air compressor size you need is the most important part of choosing the right compressor.
Select something too small, and your pneumatic tools (or air-powered tools) won’t run properly. Too powerful, and you could risk damaging equipment or paying for more than you need.
However, “size” in the case of air compressors doesn’t mean their length and width. When we talk about air compressor sizes, we’re talking about how much air it delivers and how powerful that air is.
In this article you’ll learn all about air compressor sizing so you can select the right machine for your tools and projects.
How Do I Know What Air Compressor Sizes I Need?
The right air compressor size is the one that delivers more than enough air pressure (pounds per square inch, or PSI) at a fast enough flow rate (cubic feet per minute, or CFM) to power your tools and get the job done.
Use the chart below to get an idea of how many PSI and CFM different tools and applications need.
- Add up the CFM of all the tools you’ll use. Your air compressor should deliver about 25% more CFM than your total need.
- Find your tool with the highest PSI. Your air compressor should deliver at least that much PSI.
Air Compressor Sizing Guide Chart
| Equipment | CFM (Flow Rate) | PSI (Pounds per Square Inch) |
| Air Powered Fans | 650 – 1,600 | 40 – 100 |
| Air Saws | 50-55 | 90 |
| Breakers | 34-80 | 90 |
| Diggers | 34-36 | 90 |
| Drills (Rock and Air) | 32-120 | 90 |
| Hammers | 34-36 | 90 |
| Post Drivers | 3.5 – 42 | 90 – 100 |
| Rivet Busters | 42-46 | 90 |
| Tampers | 38-42 | 90 |
Why Does the Right Size Matter?
Using the wrong size air compressor can result in several problems, from tools failing to work properly to mechanical damage and costly delays.
- If an air compressor is too big and powerful, you’ll likely waste money, at the very least. It may also have improper pressure, causing permanent damage to your tools and system.
- If an air compressor is too small, it won’t offer the right amount of pressure. Your tools and equipment won’t operate at full power (or at all), and you’ll waste a lot more time waiting for the tank to repressurize between tool uses.
You need to carefully determine the appropriate size to keep everything working properly and safely for a variety of project uses and applications.
5 Tips for Choosing the Right Air Compressor Sizes
If you’ve ever wondered, “What size air compressor do I need to run air tools?” The following tips will help. Use these tips to understand how air compressors work, what different terms mean and what calculations to make to find the right air compressor for your projects.
1. Understand How Air Compressors Work
Air compressors have engines or motors that power air ends which draw air from around the machine and pressurize — or compress — the air. The air in the tank is known as compressed air. This compressed air is then released in a high-pressure stream, which powers your tools and other equipment.
Air compressors deliver different amounts of air pressure (PSI) at different flow rates (CFM). Each of your tools’ manuals will specify how many PSI and CFM they require to work properly for the task at hand.
Helpful Terms You Need to Know:
- Flow Rate in Cubic Feet Per Minute (CFM): The flow rate tells you how much air comes out of the compressor per minute. This is also known as the air volume. Your tools’ manual will tell you how much CFM they need.
- Air Pressure in Pounds Per Square Inch (PSI): PSI is the total air pressure of the compressed air released by the air compressor. It tells you how powerful the stream of air is. Your tools’ manual will tell you how many PSI they need.
- Power in Horsepower (HP) or Kilowatts (kW): Power refers to the amount of horsepower an air compressor has or how many kilowatts it needs. This measurement is less important than the flow rate and PSI.
2. Estimate Your Tools’ Total CFM Requirement
Often a tool’s CFM requirement will be listed on the tool itself. If not, check the manual.
- If the air compressor will power multiple tools at a time: Add up all CFM requirements to find the total CFM the air compressor needs to deliver.
- If only one tool will use the air compressor at a time: Find the highest CFM requirement.
- Example: Let’s say you have an impact wrench that uses 10 CFM, a tire changer that uses 2 CFM, and a screwdriver that uses 5 CFM and all tools will be used at the same time by three different workers. You will need an air compressor that can provide a minimum of 17 CFM (10 + 2 + 5 = 17). However, if the compressor will only power one tool at a time, the maximum CFM you need is 10 CFM.
Keep in mind, some air compressors will need a separate tank. This tank should be approximately 5 gallons for every CFM. For the example above, the tank should be 50–85 gallons. Alternatively, check the air compressor’s manual to see if it has a recommended tank size.
3. Estimate Your Total PSI Requirement
Unlike CFM, you do not have to add up the PSI requirements of all your tools. You only need to find the highest PSI requirement from among your tools and make sure the air compressor can deliver enough PSI. Generally, you do not want to have a variance of more than 50% between your lowest and highest pressure requirements on the tools as too much pressure can cause damage.
- Example: Your impact wrench needs 80 PSI, your drill needs 90 PSI and your screwdriver needs 70 PSI. The drill has the highest PSI, so you would need an air compressor that can provide at least 90 PSI.
4. Check the Project Site’s Fuel and Power Supply
Most air compressors for construction and other remote projects are powered by a gas or diesel engine. Make sure your site has ample fuel to keep the air compressor running for the length of your project.
If your air compressor uses electricity to run the motor, make sure your project site has the right type of power. Every project site will either have a single-phase or three-phase power supply. Most commercial and residential buildings have single-phase power at 115 volts. Most industrial facilities have a three-phase power supply. If you are unsure, it is best to check, otherwise your air compressor may not work or get damaged.
5. Don’t Forget Safety and Environmental Requirements
Air compressors can be very loud. If they are diesel- or gas-powered, they will also produce emissions. To keep your crews safe and neighbors happy, be sure to follow all local and federal safety laws and noise regulations.
- Read about OSHA’s rules regarding compressed air.
- Read about OSHA’s rules on occupational noise exposure.
Also, check the manual of your air compressor (or talk to your rental provider) to make sure the compressor can be used in the type of environment that is at your worksite. For example, air compressors with specialized electronics may require climate-controlled rooms or at least to be kept dry and out of the elements. Other air compressors, such as industrial towable compressors may be more rugged and designed for outdoor use and can’t be used indoors.
Find the Right Size Air Compressor at Herc Rentals
An air compressor that’s sized correctly can be a game-changer for your project and the perfect way to prepare for spring construction season. No more costly delays of waiting for an undersized compressor to refill. No more worrying if you’re wasting money or risking damage with an overpowered air compressor.
If you’re unsure what size air compressor you need, just ask the experts at Herc Rentals. They will help you figure out how much CFM and PSI you need and help you find the most practical and effective model for your project.
Browse our extensive lineup of towable air compressors and pneumatic tools or call 888-777-2700 to get started today.
