GPM and PSI: What’s the Difference, and Which is More Important?

When it comes to GMP and PSI we often get asked about what’s more important when buying a pressure washer.

Understanding the roles that each plays helps you choose the right pressure washer, but before we start, let’s get one thing out of the way: Which pressure washer you buy dependents on the job you need to do – in other words, you will need a different pressure washer for cleaning loose dirt from a driveway than cleaning globs of oil from an oil tanker.

Think of PSI as the “stripping” ability of pressure washers; the more PSI, the better stripping the pressure washer can do.

Here’s a good analogy for stripping: If you are cleaning loose dirt from a driveway with a hose, you might come across some “stubborn” dirt. If you restrict the hose opening with your thumb, the water will jet out of the hose making it easier to strip the dirt off the concrete.

By plugging the hose with your thumb, you increased the PSI, which the same as increasing the stripping ability of your hose.

GPM, on the other hand, is the “moving” ability of the pressure washer. Using the same example as above, if while you are cleaning the driveway with a hose you come across a few small rocks, you might need to open the spigot and let more water through to help move the rocks.

By letting more water through the hose, you increased the GPM, which is the same as increasing the moving ability of your hose.

At Professional Cleaning Systems we’ve seen it all – we’ll take the guesswork out of buying your pressure washer. After you tell us what you are cleaning, we will show you how well your new machine will do the work.

We will demo the pressure washer that fits your needs and make sure you have no doubts about having the right machine for the job.

Call us at 800 678 7840, or visit us at one of our three locations for more information – we’d be glad to help you.



Serving Wichita, Topeka, Hutchinson, Salina, Great Bend, Hays, and Dodge City KS since 1988.