What is more important on a pressure washer: PSI or GPM?

Both matter together—multiply PSI × GPM to get Cleaning Units (CU). PSI (pounds per square inch) is the stripping force that breaks grime loose, while GPM (gallons per minute) is the water volume that flushes dirt away. For washing cars, you actually want moderate pressure (1,500–2,100 PSI) and higher GPM (1.5–1.76+ GPM) so you don't damage paint.

Why do upright electric pressure washers keep tipping over?

Many older 2-wheel upright carts mount the heavy motor high off the ground and connect the high-pressure hose near the top handle. Every time you tug the hose, leverage pulls the cart onto its face. Choosing a 4-wheel low-center-of-gravity unit (Westinghouse ePX3100v), a cube (Kärcher K1700 Cube), or a flat jobsite cage (DEWALT DWPW2100) solves tipping completely.

Do I need a gas pressure washer or will a 120V electric model clean my driveway?

A 120V electric pressure washer (2,000–2,300 PSI) will clean patios, decks, siding, cars, and small walkways well using a 15° or turbo nozzle. However, if you have a large two-car concrete driveway or want to spin a 15-inch steel surface cleaner (SIMPSON 80165) at full speed, a 3,200 PSI / 2.5 GPM gas washer (SIMPSON MegaShot MSH3125) finishes the job in less than half the time.

Interactive spec matrix

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Pick any three pressure washer models. We flag the winner on every scored spec so the choice makes itself.

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Overall Electric Washer (Won't Tip Over)

WestinghouseWestinghouse ePX3100v Electric Pressure Washer — 2100 Max PSI, 1.76 GPM, 4-Wheel Anti-Tip

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Heavy-Duty 120V Cleaning & Quiet Induction Motor

Greenworks ProGreenworks Pro 2300 PSI TruBrushless Electric Pressure Washer (2.3 Max GPM, PWMA Certified)

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Driveways, Sidewalks & Heavy Concrete GrimeSpec leader

SIMPSON CleaningSIMPSON Cleaning MegaShot MSH3125 Gas Pressure Washer — 3200 PSI, 2.5 GPM, Honda GC190

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Max pressure

2,100 PSI

2,300 PSI

3,200 PSIBest

Max flow

1.76 GPM

2.3 GPM

2.5 GPMBest

Cleaning units

3,696 CU

—

8,000 CUBest

Hose length

20 ft

25 ftBest

Washer Category

Low-Profile 4-Wheel Electric

Brushless Induction Electric

Homeowner Gas Pressure Washer

Price Tier

Mid-Range

Premium

Best For

Overall Electric Washer (Won't Tip Over)

Heavy-Duty 120V Cleaning & Quiet Induction Motor

Driveways, Sidewalks & Heavy Concrete Grime

PSI · GPM · Cleaning Units

2,100 Max PSI · 1.76 Max GPM · 3,696 CU

2,300 Max PSI · 2.3 Max GPM (1.2 rated @ max PSI) · PWMA Certified

3,200 PSI · 2.5 GPM · 8,000 CU

Motor / Engine & Pump

13-Amp 120V electric motor · Auto-stop Total Stop System pump

14-Amp 120V TruBrushless digital induction motor · Axial pump

Honda GC190 / Kohler 190cc OHC engine · Maintenance-free axial cam pump

Hose, Nozzles & Frame

20 ft hose · 4 quick-connect tips (0°, 15°, 25°, soap) + 600ml foam cannon

25 ft kink-resistant hose · 5 QC nozzles (15°, 25°, 40°, soap, turbo)

25 ft MorFlex M22 hose · 5 QC nozzles (0°, 15°, 25°, 40°, soap)

Weight & Power Source

20.0 lbs · 360° 4-wheel anti-tip base · 35 ft GFCI cord

43.9 lbs · 10" wheels on steel cart · 35 ft GFCI cord

64.0 lbs · Unleaded gasoline · 10" pneumatic tires

Main Trade-Off

Included 20-foot hose is fairly stiff—adding a 25-foot flexible uberflex-style extension hose lets you walk around a full SUV without moving the base.

At 43.9 lbs, it is more than twice as heavy to lift into a trunk as the 20 lb Westinghouse ePX3100v.

Requires gas/oil maintenance and Pump Saver winterizing before freezing temperatures.

Spec wins

0 / 4Check price on Amazon

1 / 4Check price on Amazon

4 / 4Check price on Amazon

The verdict

SIMPSON Cleaning MegaShot MSH3125 Gas Pressure Washer — 3200 PSI, 2.5 GPM, Honda GC190 wins 4 of 4 scored specs.

Based on listed max pressure, max flow, cleaning units, hose length. Match it to how you’ll actually use it.

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