What Size Angle Grinder Should I buy

There are several factors to consider when selecting the right sized angle grinder, but what you should understand is that a grinder’s size is determined by its discs, not the length of the overall tool. The size of the angle grinder you buy should depend on the size of job you have. For example, a 7-inch grinder will cut though small pieces of wood in no time, but using that same grinder on a wooden beam will be more of a chore. Typically, the most common size of an angle grinder is 4.5 inches, meaning that it uses discs that are 4.5 inches in diameter, and is a sufficient size for most workshop projects.

Bigger wheels or discs will make deeper cuts. If you have a concrete slab that is three inches thick, a 4.5-inch wheel will not cut through it, because the 4.5 inch wheel only sticks out at half the diameter – or only 2.25 inches. For this project you will need a larger grinder, such as the 9-inch model, which extend out at 4.5 inches.

Smaller discs at smaller circumferences will spin at faster speeds than larger discs – topping out at speeds over 11,000 rpm, making these tinier wheels ideal for cutting and polishing metal. However, smaller wheels are also susceptible to overheating. For this reason, experts will recommend buying an angle grinder that has an adjustable speed setting so it it not constantly running on the highest speed.

Know Your Amps

Keep in mind that there are some other laws of physics to consider. Grinder speed is also determined by the motor’s amp rating. So even though a 4.5-inch grinder is faster than a 6-inch grinder, the 6-inch grinder using a 13 amp motor is going to be just as fast, if not faster, than the 4.5 inch grinder with a 7 amp motor. Always review the rpm rating before making that decision.

Educate Yourself On Safety

Whatever size grinder you decide to buy, safety is always a top concern, and so it is important to wear safety gear like a face plate to avoid getting hit with debris. Also, gloves are recommended to have more control over the tool’s spinning vibration.

For novices, it’s best to start out with a smaller grinder and get used to the feel of this tool before upgrading to a larger one. The 7-inch models, for example, require two hands to operate because they put out so much power. The nine-inch grinders, for example, were once very popular in industrial complexes, but are now outlawed in many areas because they have caused so many accidents.


With a little due diligence, choosing an angle grinder that is the right size for your needs is not as complicated as you think. Smaller grinders are perfect for most homeowner or DIY hobbyist needs – their lighter weight and small frame makes them an ideal size for many projects, and also require less energy to run. Understanding the overall differences in grinder sizes will help you find the perfect model for your needs.

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