It doesn't matter if you're a contractor or a hobbyist, if your air compressor isn't able to keep up with your air requirements you're going to have a long, frustrating day. When you're in the middle of a project, there's nothing worse than needing to pause every few minutes to let your compressor catch-up. Our air compressor buyers guide will help you find the best air compressor for you and your projects.
Buying an air compressor doesn't need to be an overwhelming experience. With a little upfront knowledge, before you know it, you'll be working on your projects with a compressor that matches your individual needs. Our air compressor buyers guide will cover everything you need to know to make an informed buying decision.
Air Compressor Buyers Guide
Finding the Right Air Compressor
Finding the right air compressor is an important part of being able to properly complete a project. Many professionals own multiple air compressors since they work on a wide range of projects. But if this is your first air compressor you'll want to find one that most closely matches your job/project requirements.
Portable compressors are a good fit for home and job site work, where stationary compressors are better suited for powering production and automotive air tools because of the high volume of air they're able to deliver.
Advantages of Using an Air Compressor & Air Tools
Using an air compressor has many advantages, and if you've never used air tools before, you're in for a real treat. Air tools are far more powerful than regular electric tools. They're also able to deliver a higher torque and RPM which helps you complete your job quickly with less effort.
Air tools are easily interchangeable and versatile. Many homeowners frequently use air drills, impact wrenches and air nailers, and if you own a larger air compressor, you may want to consider purchasing an air sander. Air shears and nibblers are also popular if you need to slice through aluminum, plastic, tin, or corrugated sheet metal.
Professionals that do more demanding work use an industrial grade air compressor. These stationary units can deliver more horsepower, more PSI, more CFM and have longer run times. They frequently have large tanks, sometimes up to 120 gallons which enables them to run non-stop until the job is completed.
Types of Air Compressors
Air compressors come in three basic styles: Stationary, portable, and inflator.
Stationary Air Compressors - Stationary air compressors are more commonly used by professionals, and are ideal for workshops or garages. Most have motors that can deliver between 4- to 10-horsepower, and because of their large storage tank, they can operate for longer periods without needing to recharge. In most cases a stationary air compressor is bolted to the floor and hard wired into the electrical supply.
Although, some tanks may be as large as 120-gallons, they typically have tank sizes in the range of 60- to 80-gallons. In order to reduce floor space, stationary air compressors have a vertical design.
Portable Air Compressors - These are by far the most popular air compressors and they're available in a variety of sizes and shapes. Portable air compressors are more compact than stationary units and have smaller tanks, ranging in size from 2- to 6-gallons and 20- to 30-gallons. They are typically less expensive than stationary units.
A portable air compressor is designed to move from one job site to another, so you'll find handles and/or wheels built into the design. Many of the smaller units are excellent for light-use such as airbrushing; larger units can power nail guns, sanders, and the majority of other air tools.
Inflators - Although an inflator may technically be a portable air compressor, they really fall into their own category. They are by far the smallest of air compressors and since they aren't equipped with a storage tank, they'll need to run continuously in order to provide air. Inflators are excellent for inflating tires, inflatable kayaks, pool toys, and sports equipment.
What Size Air Compressor Do You Need?
We'll cover this topic in detail in the next section, but keep in mind that determining the correct size is critical and arguably the most important decision you'll make when it comes to buying an air compressor. Talk to any air compressor owner, and we doubt you'll hear any regrets about purchasing an air compressor that's too powerful. But you'll almost certainly hear dissatisfaction if the compressor is too small.
The general rule of thumb is to match the air compressor to the demands of the job; however, you should always error on the side of buying a unit larger than your needs. Plus, once you start using air tools you may find you like them so much you'll need more power than you expected.
Air Compressor Power Ratings
When you start shopping for an air compressor, you'll see a lot of ratings thrown around. Acronyms such as HP, PSI and SCFM. Sure, you probably know what they stand for, but how do they relate to buying an air compressor? Let's take a closer look.
The horsepower (HP) rating indicates the power of the motor. If you're looking at purchasing an industrial compressor, the HP is probably pretty accurate. But unfortunately, smaller, consumer compressors are often over hyped in their HP ratings.
If you're looking at purchasing a 5-HP motor, you should expect it to draw roughly 24-amps and require a 220-volt circuit. But many consumer compressors are rated with a 5-HP motor, yet draw 15-amps on a 110-volt circuit. This is one of those "buyer beware" moments: If you're purchasing a 5-HP rated motor that's designed to be plugged into a standard electrical outlet, the motor is overrated, and it's more accurately able to deliver 2-HP.
Another thing to keep in mind, is that electric motor HP is rated differently than gas engine HP. An industrial electric compressor is twice as powerful as a gas compressor. In most cases, you'll find air compressor horsepower ratings fall in the range of 1.5 to 6.5 HP.
Horsepower is an important rating to consider as it can give you an idea of the model's power. But, with that said, it is not as important as the SCFM rating (covered below) which indicates the amount of power the compressor delivers to your tools.
Pounds per Square Inch
Pounds per square inch (psi) measures the amount of air pressure the compressor generates within the tank. The majority of tools require 90-psi to operate, which is why this is a common metric you'll see when shopping for an air compressor. Although, some of the more powerful compressors are capable of generating over 150-psi.
Keep in mind that the compressor will need a higher shut-off pressure in order to maintain the tool at 90-psi. Because of this, many industrial compressors use a two-stage design. We'll go into more detail about single and two-stage compressors below.
Standard Cubic Feet per Minute
When matching an air compressor's capabilities to the requirements of pneumatic tools you'll need to know the Standard Cubic Feet per Minute rating, most frequently referred to as SCFM. Many manufacturers refer to it as Cubic Feet per Minute (CFM) in their literature.
In simple terms, SCFM is the amount of air a compressor is capable of delivering in standard conditions. Since tools that are powered by an air compressor require a certain amount of air flow for the tool to operate, the SCFM rating is a critical metric.
Smaller tools typically require up to 5.0 SCFM, where a larger tool may require 10.0 SCFM or even more. Since the actual SCFM delivered can be adjusted by the pressure of the air within the compressor (psi), it's important to compare the SCFM ratings as they relate to psi.
All manufacturers list this information in terms of "SCFM @ psi" (ie. 5.0 SCFM @ 90 psi), and it's not uncommon to see several different SCFM ratings at different pressure levels. However, since the majority of air tools require 90 psi to operate, this is the most important rating.
How to Determine SCFM Requirements
Determining your SCFM requirements is the most important step in purchasing an air compressor because this metric will determine how large of a unit you'll need. The simplest way to find your minimum compressor SCFM rating is use your tool with the highest SCFM requirements, then multiply by 1.5.
As an example, if your highest rated tool is an orbital sander that requires 6 SCFM to operate, you'd need to purchase an air compressor that can deliver 9 SCFM @ 90 psi (6 x 1.5 = 9). Using this formula will give you a little leeway, which is always a good.
Keep in mind, that if you plan on running multiple pneumatic tools simultaneously, this won't be enough power. The way to determine the minimum SCFM compressor rating you'll require for multiple tools is to find the SCFM rating for each tool you'll be running at the same time.
Air Tool CFM Chart
The chart below lists the most common air tools with their average CFM requirements. Air tools are rated on a 25% duty cycle (for every 60-seconds the tool is in use for 15-seconds). If you are planning to use a continuous use tool, such as a orbital sander or grinder, it's a best practice to multiply the CFM by 4.
Average CFM @ 90 psi
Average Operating psi
70 - 90
125 - 150
100 - 130
2 to 3
90 - 100
120 - 150
90 - 100
90 - 100
Impact Wrench: 3/8"
90 - 100
Impact Wrench: 1/2"
90 - 100
Impact Wrench: 1"
90 - 100
90 - 100
70 - 90
90 - 100
90 - 100
Paint Spray Gun
4 to 8
90 - 100
Impact Driver: 1/2"
90 - 100
Impact Driver: 3/4"
90 - 100
Impact Driver: 1"
90 - 100
70 - 90
5 to 8
90 - 100
6 to 9
70 - 100
90 - 100
Air compressors are either powered by gas or electricity. How you plan to use your compressor is the best way to choose which power source is right for you.
Electric vs. Gas Air Compressors
Electric Air Compressors - By far, electric air compressors are the most common models purchased. They run quieter and require less maintenance than their gas powered cousin. The majority of the home-use air compressors can operate on a standard 120-volt household current. However, larger models, with 2-horsepower or above, may require 220-240-volts of current.
An electric air compressor is a great choice if you're working indoors since they don't emit fumes and you'll typically have access to electricity. These units can be used with a extension cord, but check your manual to make sure it's a suitable size. Extension cords do limit mobility, but in most situations it's a minor inconvenience.
Motor damage may occur if you power an electric air compressor with a generator. In addition, they should never be used in a damp or wet environment.
Gas Air Compressors - Gas-powered compressors are popular among remodelers and builders because they don't require an external fuel source. Their high output and job site convenience makes them an excellent choice for outdoor work and on job sites where electricity is unavailable.
Generally speaking, you can expect a gas air compressor to generate higher levels of psi than an electric model. This is because they typically have motors with more horsepower. The downside of these powerful units is that they require more maintenance and emit exhaust. They are excellent for outdoor use, but should never be used in an unventilated area.
Air compressors have two different types of pumps: Single Stage or Two-Stage, as well as a choice between oil-lubricated and oil-free.
Single Stage vs. Two-Stage Pump Type
Single-Stage Compressors - A single-stage air compressor will have one or more cylinders pumping air into the tank. Each cylinder is operating at the same pressure. Single stage compressors are common with home or light-duty commercial units.
They'll shut off within the 125 to 135 psi range, and typically kick-in around 100 psi. Considering that you lose pressure due to restrictions in the couplers and hose, you may find that you won't have enough pressure to drive some higher demand air tools.
Two-Stage Compressors - A two-stage compressor will have two or more cylinders. The first cylinder (first stage cylinder) will pump air into another cylinder (second stage cylinder). The second stage cylinder compresses the air further before pumping it into the tank.
In most cases the first stage cylinder will bring the pressure to 90 psi, then pass it to the second stage cylinder where the pressure is increased to 175 psi. A two-stage compressor is the best choice if you require high pressure, but in most home applications, a single-stage pump will work just fine, and often better. Industrial compressors frequently use a two-stage design.
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Oil-Lubricated vs. Oil-Free Compressors
Oil-Lubricated Compressors - These compressors, just like your car, requires oil to operate. In order to prevent excessive wear, the oil lubricates the moving parts inside the pump. Oil-lubricated compressors are typically heavier and larger than an oil-free compressor of the same size. They also require more maintenance as you'll need to regularly monitor the oil level and change as needed in order to prevent premature wear and damage.
Oil-Free Compressors - The popularity of oil-free compressors is due to a number of factors. First, they require virtually no maintenance. That means you won't need to worry about checking or changing the oil. In order to prevent unnecessary wear, the cylinder and other moving parts are coated with a special material similar to the substance applied to non-stick pans.
Oil-free compressors are great performers when it comes to light- to general-duty jobs, and since they're lighter and smaller than oil-lubricated compressors, they're also very portable and easy to move from one job site to another.
Direct Drive or Belt Drive Compressors
Direct Drive Compressors - A direct drive compressor spins at the same speed as the motor because it's directly connected to the motor shaft. The majority of quality direct drive compressors are low RPM and typically turn at 1,725 or 3,450 RPM's.
There are some oil-less direct-drive air compressors on the market, however, the quality is hit-and-miss. Your better option may be to purchase a belt-drive, oil-lubricated compressor. Although, if portability is a concern, this may not be the right move for you. One word to the wise: Beware of high-speed, oil-less compressors.
Belt Drive Compressors - A belt drive compressor is more efficient than a direct drive system because the pump can turn much slower than the motor. This allows them to operate with less wear and tear. The majority of belt drive compressors use what's called splash lubrication, which simply means that oil is splashed around the compressor crankcase.
Provided you keep your oil at the recommended level, a belt driven compressor should have a long service life. This is mostly because there's less heat transferred from the motor to the pump, and less vibration.
Air Compressor Tank Size & Style
The role of a compressor's tank is simply to store the compressed air, it does not produce the air. If the motor and pump on the air compressor is capable of producing the amount of air needed, then the size of the tank doesn't really matter because you'll never run out of air.
With that said, the tank gives the user a buffer and allows the user to run the air tools without the compressor operating. The amount of time the air tools run before the compressor kicks back on is determined by the size of it's tank (and of course, the requirements of your air tools).
How Large of a Tank Should I Buy?
Air compressor tanks are rated in US gallons, and range in size from 1 gallon to 80 gallons. Although, it may seem counterintuitive, buying the biggest tank isn't always the best choice. Tools such as brad and finish nailers only require quick bursts of air, which drains the tank relatively slowly. A 2 to 6 gallon tank will most likely be fine for these types of tasks. In addition, smaller tanks are far more portable and are able to build to pressure quicker.
When the air tool is only used intermittently, a smaller tank size will be sufficient. If the compressor pump is above the tool's SCFM requirement and the tank is large enough to meet the needs, the compressor will have time to cool between cycles.
However, you should consider purchasing an air compressor with a larger tank if you'll be running air tools continuously that require a high volume of air. But you shouldn't solely depend on your air tank for higher demand tools such as sanders, many professionals recommend purchasing an air compressor that can produce the amount of air to match the sander's SCFM requirements.
Which Tank Style is Best?
Air compressors come in a variety of tank styles. Some of the more common ones are pancake; hot dog; twin-stack, and wheel barrow. Each has it's own set of advantages. The best tank style for you will be based on how you plan to use your compressor. As an example: If you're willing to trade portability for more power than a pancake tank isn't for you. Let's take a closer look at each style:
Pancake Air Compressors
The air tank on a pancake compressor is round, flat, and positioned on the bottom of the unit which increases stability. They are lightweight and have small tanks, which makes them extremely portable and easy to store.
Pancake air compressors are relatively maintenance free due to their oil-free, belt-less design, and are an excellent choice if you're a hobbyist with small tasks around the house. They are excellent at filling sports balls, pool toys, rafts, bicycle tires and running many lower demand air tools.
Hot Dog Air Compressors
A hot dog air compressor has one single horizontal long tank which is typically larger and heavier than a pancake compressor, although, no less portable. Frequently hot dog compressors are designed with a roll cage and handle to enable the user to safely transport them from one job site to another.
Most hot dog compressors are oil-less, so they require very little maintenance. They are great for hobbyists and finishers because they can easily operate staplers and airbrushes as well as other air tools.
Twin-Stack Air Compressors
Just like the name implies, a twin-stack air compressor has two air tanks stacked on top of one another. The advantage of this design is the added air capacity without the need for additional floor space. The additional stored air allows you the ability to run your tools for longer periods between cycles.
Twin-Stack air compressors have enough power to run nailers and brad guns, and are an excellent choice for DIYers as well as professionals looking for a portable unit.
Wheelbarrow Air Compressors
A wheelbarrow air compressor also has twin cylindrical air tanks, however they are outfitted with handles and a wheel to allow the unit to be easily moved from from job site to job site.
Air Compressor Optional Features
Here are a few of the most common optional features you may find on an air compressor:
Air-Cooling System - Buying an air compressor that utilizes an air-cooling system to cool the pumping machinery will help extend the motor life.
Thermal Overload Switch - If your motor overheats, the thermal overload switch will automatically shut down the motor. This will not only protect your air compressor, but it will also protect your air tools.
ASME Certification - This certification indicates that the air compressor tank has met the American Society of Mechanical Engineer's material and craftsmanship standards. The certification seal will be located on the tank.
Roll Cage - Roll cages provide protection to the air compressor's tank and components.
Low Oil Shutdown - If the oil level in your air compressor drops below a safe level the system will automatically shutdown. This feature protects your unit from damage and prevents costly repairs.
Continuous Speed Operation - This feature is available on some of the higher-end air compressors. Instead of the compressor automatically starting and stopping when preset cut in/cut out pressure levels are reached, the continuous speed unit will run 100% of the time. Continuous Speed Air Compressors automatically adjust their air output to meet the need. Many dual control compressors offer both continuous speed and auto start/stop speed operation.
V-Design Cylinder - This feature is also available on higher-end air compressors, but purchasing an air compressor that utilizes V-Design Cylinders is always your better choice. An air compressor's worst enemy is heat, and since V-design cylinders tend to run cooler than in-line cylinders you can expect a longer service life.
Service Life Expectancy
Unfortunately, price isn't always the best indicator when it comes to buying a quality air compressor. Brand reputation and individual model research is always the preferred method to make a buying decision. Keep in mind that many lower-end air compressors are designed to be disposable and are simply not worth repairing.
To help give you an idea of service life expectancy, many manufacturers state how many hours you can anticipate to run the compressor before service is required. For example, the California Air Tools CAT-1P1060S is designed to provide over 3000 hours of use before the oil-free single piston pump shows wear.
As a general rule and with all things being equal, you can expect an air compressor in a hobbyist shop to outlast one in a pro shop, simply because they'll be used so differently.
Air compressors typically don't have a "hard rule" as to when they should be retired. As long as the motor is running strong, the condensation within the tank doesn't have rust flakes, and the air seals are still viable and holding, it's fair to say the unit is still full of life . . . regardless of it's age.
How to Extend Service Life
Taking care of your air compressor will help you extend it's service life. Here are a few things that you can do:
- Check the oil level and change it regularly.
- Check and replace the filter regularly.
- Drain the tank after each use.
- Keep the cast-iron surfaces inside the tank dry.
- Do not prolong making repairs.