While the capacity/size of the compressor is a good thing to have and usually means you can reliably run off most air tools, it's not always the case.
What size air compressor do I need? This is a common question for many DIY hobbyists and new contractors looking to get into air-powered tools. While most people "just wing it" and get lucky sometimes, it's always advisable to know the actual size, shape, and make of an air compressor that is the best fit for your tools.
Some manufacturers, like EMAX, have put significant research and development time into creating air compressors as small and lightweight, and as huge and heavy as possible without compromising on performance. But not all manufacturers are focused on minimizing size. This makes it almost impossible to assess an air compressor's capability by it's size only.
Related: How To Use A Stump Grinder
What Size Air Compressor Do I Need?
To determine the correct size of the air compressor for your needs, check the highest value CFM and PSI of your tools. Multiply the CFM by about 1.5 to get the best margin CFM required for better and safe use. Once you get the value, find an air compressor that meets the requirement. For instance, if you have a spray paint gun that requires 5 CFM at 90 PSI, select a compressor that delivers at least 7.5 CFM at 90 PSI.
What is CFM? Are there any other factors that determine the size of the air compressor that you will need?
When buying a garage air compressor, you want to get the most of your money and investment. This starts with getting precise information on the different types of air compressors, tools, fasteners, and accessories.
To help you choose the suitable air compressor for your home garage, we've put together this comprehensive air compressor buying guide.
7 Factors To Consider Before Deciding On The Air Compressor Size
Physical Dimensions/ Storage Space
How much storage space do you have? The total area taken up by the air compressor is among the first things you should consider when you think of what "size" air compressor to buy.
Air compressors with large storage tanks take up more space per square inch. It is essential to choose an air compressor that will fit your desired room without being squeezed. To allow for proper airflow to your air compressor and easy servicing, it's recommended to allow a minimum of a three-foot radius around the unit.
A portable compressor does not necessarily require the same space as it can always be moved outside or to a less congested area during operations or servicing.
Related: Pressure Washer
Air Tool Types & CFM Requirements
Before assessing an air compressor's capability by its physical size, you should first check how much air it delivers (measured in Cubic Feet Per Minute) and the air pressure rating (PSI). Most air compressors for powering home tools fall within the 10 to 110 Cubic Feet per Minute (CFM) range.
NOTE: Air compressors that have lower CFM ratings of about 10-15 are usually enough for tire inflation and home tools such as air hammers, air grinders, nail guns, and sanders, among others. Higher CFM air compressors with a CFM rating of 50 and above are usually designed for industrial applications and larger tools, including jackhammers, rock drills, and larger impact wrenches.
Important POINTS to remember when checking the CFM requirements:
Always go with a compressor with a slightly higher CFM rating listed as a requirement on your most powerful air tool.
If you are running multiple tools simultaneously, add up their CFM rating to determine your need.
Note the CFM duty cycle rating. All reciprocating compressors are rated for a specific duty cycle. A 100% duty cycle means that the compressor can consistently deliver CFM & PSI when you are using the compressor. A 50/50 duty cycle compressor runs 50 percent of the time, while a 75/25 duty cycle compressor runs 75 percent of the time.
—you will need a higher CFM rating if you don't want to stop regularly.
The Average CFM Requirements For Common Home Tools (cfm at 90 psi)
Air Tools | CFM
Needle Scaler :8-16
Impact Wrench-1" :10
Dual Sander :11-13
Rotational Sander :8-12.5
Orbital Sander :6-9
Angle Disc Grinder-7" :5-8
Speed Saw :5
Cut-Off Tool :4-10
Grease Gun :4
Hydraulic Riveter :4
Impact Wrench-3/8" :2.5-3.5
Impact Wrench-1/2" :4-5
Mini Die Grinder :4-6
Framing Nailer :2.2
Brad Nailer : 0.3
CFM and PSI go hand in hand.
The PSI (Pounds per Square Inch) indicates the air pressure per square inch of area.
Nearly all modern air compressors offer adequate PSI to operate small to medium home tools.
However, a larger PSI has more benefits. This includes a higher pressure which translates to more air volume production in both the electric and gasoline air compressors.
As a rule of thumb, always get an air compressor with a 20 percent more PSI than what your tools require. This difference ensures that you always get enough pressure to get the best from your air tool without the issue of frequent drops in pressure below the minimal rating.
If you run a pneumatic air tool without the correct PSI gap, it will struggle to do its job.
"Focus more on the CFM."
A majority of home-use air tools require 70-100 PSI, while most air compressors are graded at 135 PSI, so you should be fine.
Tank Size/ Air Capacity
Pneumatic tools run off stored pressurized air.
How large your tank usually determines how often the compressor motor has to turn back on to re-pressurize the air, the number/size of tools, and the projects you can undertake at a time. There's a wide range of tank sizes, starting from 2 gallons up to 80 gallons. There are bigger options for commercial use.
First, sustained tasks require a constant supply of compressed air. If the tank is too small, it will lose pressure as the cylinder empties, causing a dip in the tool's performance.
Smaller tanks have to run often to maintain pressure. This means they can neither sustain tasks and tools such as grinders and sandblasters requiring continuous airflow. You'll have to stop working more frequently to let the air compressor re-pressurize and cool off. However, for tools that need quick bursts of air, air, you can get by with a smaller tank.
Types Of Tank Types Based On Tank Capacity
"bigger isn't always better."
Your air tool(s) CFM and PSI rating can affect the speed at which compressed air is consumed. Larger air tools consume more and will deplete your tank supply faster. With that in mind, here is a quick rundown of different types of air compressors with varying tank capacities.
– Pancake -
They are typically smaller and lightweight and have a round storage tank with a tank capacity between 3 to 6 gallons. Pancake air compressors are designed to handle lighter duties making them a common choice for home and hobby users.
– Pontoon -
Also known as horizontal/hotdog air compressors. These compressors have a tank that lays flat rather than vertical. With a capacity ranging from 1 gallon to 30 gallons, they are the most sought-after portable air compressors by DIY enthusiasts and contractors. At the high end of the scale, horizontal air compressors are also available in stationary models designed to sit in one place.
– Twin Stack -
Twin stack models solve the CFM problem of having to wait for the air tank to refill. As one tank empties during use, the other tank remains full. This increases your capacity and lets you work on your project continuously.
Twin stack models have a capacity range of 5 - 10 gallons and a PSI rating of 135 to 150 with the cfm at 90 psi, ranging between 2 and 5.
– Wheelbarrow -
Just as the name suggests, this air compressor has a wheelbarrow-like design –they have two large handles at one end and one pneumatic wheel at the other. They are extra portable, have a capacity of about 10 gallons, and are mainly gas-powered, making them the ideal choice for professionals who are always on the move from job to job. Note that they can't be classified as lightweight, as some can be as heavy as 150 pounds!
– Vertical -
If you are looking for the best home garage air compressor that will fit in confined spaces, a vertical air compressor is a great choice. The smaller models with a capacity of 10 to 30 gallons have wheels and a handle to help you move them around quickly. Larger, 60+ gallon models are usually stationary, designed to be placed in one place.
Electric air compressors / tankless
Electric compressors are the most common models preferred by users.
They have a quieter operation, are easier to use in terms of convenience, generally cost less money, and require less maintenance than their gasoline counterparts. They are also much better for indoor air compressor jobs.
If you are working at home most of the time, you are better off with an electric compressor.
Many electric compressors can be connected to a standard home outlet, but larger air compressor models might require 240 v.
Some of the most apparent drawbacks for electric compressors include:
They don't function well (or at all) when using a standard house extension cord. In some cases, it can even be a safety hazard in some cases. Air compressor manufacturers might indicate alternative specifications for extension cords.
They are virtually useless if you have nowhere to plug in.
They are not so good for heavy-duty jobs and might wear out faster. They are better suited for "trim & finish" work and light tools like nail guns or a spray gun.
Gasoline-powered air compressors are the workhorses when it comes to air compressors.
A gas compressor provides you with more freedom to work almost anywhere. They are a great option in locations where electricity is not readily available. This could be farms, construction sites, and the roadside, among others. Gas compressors typically generate greater PSI and have more horsepower than electric models.
With gas compressors, you don't require electrical hookups of any sort. Simply fill up the gas tank and do the job anywhere!
However, while gas-powered compressors have tremendous advantages in their flexibility of location, their main disadvantages include:
Being bulky. They tend to be considerably big, so the storage and transportation could somewhat be an issue.
They produce fumes and noise, which is okay if you are operating the machines outside. If using inside, the toxic fumes could be dangerous to your health. Also, gasoline is highly flammable, so you absolutely have to be 100% dedicated to proper maintenance. If you can do that, you have nothing to worry about.
This is the mechanical energy required by an air compressor to complete its task of compressing air in a given amount of time. In simple words, it's the overall power of your air compressor motor. Typically most air compressors with a pressure average of 90 psi air have an HP rating ranging between 1.5 and 6.5. Larger stationary air compressors can have up to 15 HP.
For small portable air compressors, the HP is not a big issue. Larger HP does not equal efficiency. The right HP should be considered along with the CFM and PSI of the tools.
It is in accordance that a 5 HP air compressor cannot do the same amount of work as a 10 HP one.
However, when you combine other factors like CFM, PSI, and tank capacity, a 5HP compressor can provide adequate power and efficiency, making the 10HP an overkill that'd just be wasting power.
Noise and Vibration Levels
Larger compressor units, especially gas-powered ones, can be extremely noisy due to the vibrations through floors. This can lead to decreased productivity, unhappy neighbors, or unhappy employees. If you are operating around people and inside homes frequently, you may want to reevaluate the choice and size of your compressor.
Consider electric options like the Oasis 12-Volt Continuous Duty Tankless Air Compressor - XD4000-12 for medium to large jobs and the EMAX 30-HP Tankless Rotary Screw Air Compressor w/ Variable Speed Drive - ERV0300003D for large to commercial projects.
Important Air Compressor Tips To Remember
An electric pump reduces complex maintenance and prevents regular mixing of oil into compressed air.
A belt-drive air compressor system has a quieter operation than a direct-drive system.
An adjustable exhaust for a gas-powered air compressor helps direct exhaust away from your work area.
Get a multiple coupler attachment for your compressor machine. It allows you to handle different tasks without connecting and disconnecting tools.
Multiple air compressor accessories and tools add value to your investment.
While there are other features to consider before purchasing an air compressor, keep in mind that the most important considerations are the CFM and PSI.
Remember, a bigger tank doesn't necessarily mean a better air compressor.
Safety: As with any power tool, always remember to wear ear protection when using an air compressor.
Choose the right brand. For decades, brands like EMAX & Oasis have created the best industrial air compressors and extreme duty air compressors. They have a good reputation for building quality and highly efficient machines.
Choose the right size. Buying a too-small compressor can waste time waiting for pressure to build up, and using a too-big compressor can waste resources.
A cast-iron construction can add a few extra years by protecting your air compressor against water and extreme temperatures.
Choose an air compressor that provides enough operational airflow.
Know your work environment to determine whether to buy an electric motor or a gasoline engine.
Electric motors are less expensive and require less maintenance.
Gasoline air compressors offer increased portability.
If you are unsure of what size you need for your tools, contact your local LandMark Tools compressor distributor, and we'll help you find the right size compressor for you.
Hopefully, you've got your answer to what size of air compressor you need. All the information can be a bit overwhelming, but you'll never go wrong in your next purchase.
What Size Air Compressor Do I Need: FAQ's
Is an air compressor worth it?
You may never want to use hand tools again once you experience the powerful benefits of air compressors and pneumatic tools. They make it possible to achieve in seconds what might take hours to accomplish by hand.
What Size Air Compressor Is Good For Impact Wrenches?
Impact air wrenches tools require a lot of air pressure to function correctly. You will need a medium-sized tank with plenty of CFM power like the Oasis 12-Volt Continuous Duty Tankless Air Compressor XD4000-12. It has a 100% duty cycle and a max PSI of 200. It can be used with air ratchet wrenches, paint sprayers, framing nail guns, framing nailers, and sandblasting.
How Much Does A Good Air Compressor Cost?
If you're looking for an air compressor to fill some bike tires, inflate air mattresses, and occasionally fire up a finish nailer, a basic compressor (of about 3-5 CFM) can cost anywhere between $100-$500. If you will be using more pneumatic tools, expect to spend upwards of $1000
What Size Air Compressor Is Best For A Nail Gun?
A nail gun is not a continuous use tool, so it does not require a constant supply of compressed air. Instead, it uses short bursts of air to drive in the nails. So, all you need is an air compressor with at least a 2-5 CFM rating. If you'll be using the tank compressor, a 2-6 gallon tank capacity is sufficient.
What Size Air Compressor Works Best for Painting?
Painting requires constant spraying. A larger air compressor with a tank capacity of 10 gallons or its equivalent in CFM & PSI is enough for house painting jobs. This larger tank will help you avoid pausing every few minutes to refill.
If you are looking to paint cars, it's advisable to go with the 60-gallon tank with a 5-6 HP and a CFM output range of 14-18 at 90PSI. A compressor with a less CFM output can still handle paint guns, but it would result in over-spraying, especially in the clear coat stage.