Choosing an air compressor to run a die grinder can be a hassle if you don’t know what you’re doing. There are so many factors to consider before making this choice. For example, how big of an air compressor for a die grinder?
The size of an air compressor is calculated by multiplying the CMF rating of the die grinder with the duty cycle of the compressor (typically 50%) and the minimal time of operation. The result should be divided by 6 to get CFM at 90 PSI.
The details of this equation will be covered below. However, there are several other factors to consider before buying an air compressor for a die grinder. These include:
- How long will you use the die grinder
- The CFM rating of the die grinder
- The duty cycle of the air compressor
- Size of the tank (detailed)
- The length of the hose between the air compressor and the die grinder
In this knowledgebase blog post, we will discuss everything you need to know about how big of an air compressor you need for die grinders. To do that, we need to delve into the nitty-gritty details of the factors listed above.
What size compressor do I need for die grinder?
Read through all the following sections before deciding how big of an air compressor to get for your die grinder.
How long will you use the die grinder?
If you have a die grinder project, you need to ask yourself whether you will use the machine continuously or intermittently. This is crucial for determining the power of the air compressor.
For example, a small air compressor should do the trick for intermittent die grinder work. Conversely, you will need a large air compressor for more demanding projects. Each die grinder mentions the required CFM rating.
Luckily, most die grinder projects don’t require a long operation period. In fact, you are unlikely to draw the maximal capacity more than half of the time.
The CFM rating of the die grinder
CFM ratings or die grinders are another important factor to consider. You can find these figures in the manual of the die grinder. If you decide to buy a die grinder online, its CFM will be mentioned in the description.
Note that manufacturers display the unit as SCFM, which stands for standardized cubic feet per minute. This fancy term just means that the CFM was measured at a temperature between 60°F to 68°F, atmospheric pressure (14.7 PSI), and a 36% humidity level.
You may also come across the operating pressure of the die grinder. However, you don’t need to worry about this. Most die grinder brands recommend an operating pressure of 90 PSI. Therefore, focus on the CFM of air compressors at 90 PSI before making a purchase.
The duty cycle of the air compressor
The duty cycle of an air compressor describes how long a motor runs before it has to stop. The majority of manufacturers base this figure on 10-minute or 1-hour intervals.
We can calculate the duty cycle using the following equation:
Duty cycle = (on-time of the compressor ÷ total time) x 100
For example, an air compressor that runs for 10 minutes and rests for 30 minutes has a duty cycle of 25%.
The table below demonstrates the on/off durations based on various duty cycles:
| Duty Cycle | Maximal On-Time | Minimum Off-Time |
| 9% Duty Cycle | 3 minutes | 30 minutes |
| 10% Duty Cycle | 3 minutes | 30 minutes |
| 15% Duty Cycle | 6 minutes | 30 minutes |
| 20% Duty Cycle | 8 minutes | 30 minutes |
| 25% Duty Cycle | 10 minutes | 30 minutes |
| 30% Duty Cycle | 13 minutes | 30 minutes |
| 33% Duty Cycle | 15 minutes | 30 minutes |
| 40% Duty Cycle | 20 minutes | 30 minutes |
| 50% Duty Cycle | 30 minutes | 30 minutes |
| 100% Duty Cycle | Offers a continuous run but requires pauses | |
| Continuous Duty | Continuous run | |
Why does an air compressor need a duty cycle?
There are three main reasons that air compressors have duty cycles:
Heat dissipation – Air compressors release up to 70% of the consumed energy in the form of heat. Therefore, it is crucial for the motor to shut down in order to dissipate the excess heat.
Efficiency of compression and quality of air supply – A duty cycle ensures the air compressor is producing a high-quality air supply.
Lifespan of the motor – Rest periods prevent the wear and tear of internal components of the air compressor, prolonging its lifespan.
Continuous CFM delivery
An air compressor that generates 10 CFM may seem like a great choice for a die grinder with a 10 CFM rating. However, you need to consider what we just discussed – the duty cycle.
Think of it this way – an air compressor with 10 CFM would only be able to deliver 10 CFM without interruption if the motor pump doesn’t need to stop. In other words, it needs to have a continuous duty cycle. If the pump has to stop every few minutes, you cannot really operate the die grinder without interruption.
To calculate the continuous ability of your air compressor to generate the CFM, use this simple equation:
Continuous CFM delivery = Duty cycle x CFM rating of the air compressor
Therefore, an air compressor with a rating of 8 CFM and a 50% duty cycle is able to continuously deliver 4 CFM.
Tank size
The size of the tank depends on what we just covered above, and a few more factors.
An 8 CFM air compressor with a duty cycle of 50% needs a tank size of about 50 gallons. How did we measure this? We just applied numbers to the following formula:
Tank Size = (Duty cycle x CFM rating of the air compressor x running time) ÷ 6
We already know what the duty cycle and CFM rating mean. The remaining unknown is the running time. For the sake of this example, we chose 10 minutes as the minimal operation time.
Some of you might be wondering about the number 6. Without dividing by 6, the result we get reflects a volume at atmospheric pressure (14.9 PSI). Remember that volume and pressure are inversely related. Differently put, the higher the volume, the lower the pressure (and vice versa).
Therefore, we need to adjust our calculations to 90 PSI (6 times the atmospheric pressure).
Tank Size = (50% x 8 x 10 minutes) ÷ 6 = 6.67 Cubic Feet
Following our formula, we’ll get the results in cubic feet. To convert to gallons, multiply by 7.48. This gives us approximately 50 gallons.
The length of the air lines
Research demonstrates that the length of air lines is disproportional to pressure values. That is to say that longer air lines will negatively impact the air pressure that reaches the die grinder. For this reason, you should always use air lines long enough to comply with your applications.
How much air does a die grinder use?
Die grinders consume between 3 to 12 cubic feet per minute (CFM), depending on their power output and applications. Some manufacturers display air consumption in the liter per minute (L/min) unit.
Here are some rough estimates of air consumption for different die grinders:
Light-duty die grinder – Light-duty die grinders consume between 3 to 5 CFM (85 to 142 L/min). These machines tend to be smaller and less powerful. Users operate light-duty die grinders for precision work.
Medium-duty die grinder – Medium-duty die grinders are more useful for metalworking and automotive applications. Air consumption for these machines ranges from 5 to 8 CFM (142 to 227 L/min).
Heavy-duty die grinder – These potent die grinders are mainly used in industrial settings. Expect anywhere between 8 to 12 CFM (227 to 340 L/min) to run these machines.
What air compressor do I need for angle grinder?
The ideal air compressor for an angle grinder should produce at least 5 CFM at 90 PSI. Air compressors that generate 8 CFM at 90 or 100 PSI are better options to avoid experiencing any issues during operation.
The smallest air compressor for an angle grinder is the California Air Tools SP-9421. This electric air compressor is very powerful, generating 5.30 CFM at 90 PSI. The maximal operating pressure of this compressor is 150 PSI, making it suitable for light and medium-duty angle grinders.
What’s more, it comes with a 24-gallon tank, reducing the time for recovery and refilling. The best part? It’s so quiet! It only generates 70 dB, which is the same noise made by a dishwasher.
| Pros | Cons |
| Very powerful for its size (5.30 CFM at 90 PSI) | May struggle with heavy-duty die grinders |
| Low noise level (70 dB) | Requires a bigger tank for some applications |
| Low maintenance cost (oil-free) | Relatively low duty cycle (30%) |
Best air compressor for die grinder
1. Campbell Hausfeld air compressor for die grinders
This massive 60-gallon air compressor gives users an array of choices to operate multiple pneumatic tools, including die grinders. The powerful electric engine generates 10.2 CFM at 90 PSI.
If you live in the United States, this air compressor is not compatible with 110-volt outlets. You need 240 volts to operate it.
| Pros | Cons |
| Extremely powerful (10.2 CFM at 90 PSI) | Requires 240-volt outlet |
| Very large air tank (60 gallons) | Relatively loud (87 dB) |
| 80% duty cycle | May cost more for maintenance (oil-flooded) |
2. DeWalt air compressor for die grinder
The DeWalt air compressor is a gasoline-powered machine that produces considerable power thanks to the Honda GX160 OHV 163cc engine.
The air compressor can generate 5 CFM at 90 PSI, which can run light and medium-duty die grinders. Despite the small air tank of this compressor (4 gallons), it has an 80% duty cycle, which compensates for its small size.
| Pros | Cons |
| Produces 5 CFM at 90 PSI | Not suitable for heavy-duty die grinders |
| Low noise level (70 dB) | Small tank (4 gallons) |
| Low maintenance cost (oil-free) | High cost |
3. NorthStar gas-powered air compressor
This extremely powerful air compressor is ideal for most die-grinder applications. It comes with a robust Honda gasoline engine that’s able to release 13.7 CFM at 90 PSI.
The operating pressure for this air compressor can reach 130 PSI. This product is famous for its long lifespan despite a duty cycle of 100%. It comes with a 20-gallon air tank. However, the duty cycle of this compressor makes it ideal for light, medium, and heavy-duty die grinders.
| Pros | Cons |
| Very powerful (13.7 CFM at 90 PSI) | Heavyweight (217 pounds) |
| Low noise level (70 dB) | Only suitable for the outdoors (gas-powered) |
| 100% duty cycle | Somewhat pricy |
Air compressor to run die grinder – FAQs
1. What air compressor adapter do I need for die grinder?
The most common connections used for air tools, including die grinders are:
1/4-inch NPT Connection – Some die grinders have a threaded 1/4-inch NPT connection for attaching to the air hose. In this case, purchase a 1/4-inch NPT female fitting on one end and a suitable connector for your air compressor’s outlet on the other end. You may also need thread sealant tape to ensure a proper seal between the connections.
Quick-connect coupler – Quick-connect couplers are essential to secure attachments to air hoses. You can find these couplers in 1/4-inch and 3/8-inch sizes. Check if your die grinder uses a quick-connect coupler.
If you are unsure about which air compressor adapter you need for the die grinder, go through the user manual or contact the manufacturer for additional information.
2. Will a 6-gallon compressor run a die grinder?
A 6-gallon air compressor may not be large enough to run a die grinder without issues. Die grinders require a high volume of pressurized air, which may not be possible to produce by a 6-gallon air compressor. Check the CFM, operating pressure, and duty cycle of the die grinder and compare them with what’s mentioned on your air compressor for a definitive response.
The main factors to consider are:
- Air consumption (CFM)
- Operating pressure (PSI)
- Duty cycle
3. What is the average RPM of a die grinder?
The average RPM for a die grinder ranges between 10,000 RPM and 30,000 RPM, depending on their brand, design, and intended applications. The RPM of some models can reach 80,000 RPM to serve highly specialized projects.
Different die grinders provide various RPM ranges. For example, pneumatic die grinders tend to generate higher speeds compared to their electric counterparts.
Just make sure to read the needed RPM for the specific task/project you’re working on.
Takeaway message
Figuring out how big of an air compressor you need for a die grinder can be overwhelming. However, once you understand the basic principles that we covered in this article, the process becomes fairly easy.
Hopefully, we managed to clear out the confusion surrounding air compressors and die grinders.
You can always leave your questions and feedback in the comment section below.
