Shop Vac: Wet-Dry Vacuum Buying Guide

A shop vac or wet-dry vac is a great tool to have around the garage or on the job site to remove dust, dirt, and wet messes of all kinds. Shop vacs are useful in wet or dry situations which means that their uses are virtually endless. If you’re looking for a shop vac, there are some specifications your should consider before making a choice.

What should you look for in a capable shop vac?


The maximum output horsepower of the motor is called peak horsepower. Although peak horsepower is often published with each shop vac, you shouldn’t get too caught up with horsepower ratings. They may not indicate the actual operating horsepower you will be using when cleaning and may not be a valid point of comparison.

Sealed Pressure

Also, not a very useful comparison specification, the suction pressure is measured with no airflow and airflow makes up a big part of a vacuum cleaner’s performance.

Cubic Feet Per Minute (CFM)

CFM is a valid comparison point. It represents how much air is moved by the motor or a specific system load. All other specifications being equal like hose type, size, and length, the accessory tool being used, and a clean filter, you want the most CFM for the money. CFM is especially important when picking up dry messes.

Sealed Suction

Airflow measures CFM (cubic feet per minute) or volume of air moved, which is important when picking up dry messes. Sealed Suction (inches) measures the raw strength of suction when picking up liquids. If you are planning to use your new wet-dry vac for mostly dry messes then a higher CFM is desirable, while if your will use it for more wet messes, sealed suction is more important. If you want the best of both worlds, the highest number for both would be ideal.

Air Watts

A newer term used by central vacuum and other machine type manufacturers to classify each model is air watts. While most agree it is not as useful as a comparison tool, Air Watts does capture both aspects of suction including sealed suction and CFM.


Make sure you get the right size vacuum for your needs. If you’re going to be regularly sucking up substantial amounts of water in a flooded basement, you should get the largest capacity that makes sense for your budget. On the other hand, if you clean up small messes around the home, car, garage, or shop, then you should be able to get away with a smaller capacity.

Remember that the published gallons figure is referring to the drum volume and not the total collection capacity. The capacity of any wet-dry vacuum depends on the type of debris you’re collecting and how clean the filter is, among other factors.

There is no doubt that a wet-dry vacuum is a must-have tool around the shop or garage. Buying the right shop vac for your needs means comparing apples to apples when it comes to specifications. Understanding shop vac specifications is important to choosing the right wet-dry vacuum cleaner for your needs.

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