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 ePX3100), a compact Kärcher K1700, 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 3,100 PSI / 2.3 GPM gas washer (SIMPSON MegaShot MS61222-S) 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 ePX3100 Electric Pressure Washer — 2300 Max PSI, 1.76 GPM, 4-Wheel Anti-Tip

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Heavy-Duty 120V Cleaning & Brushless Motor

Greenworks ProGreenworks 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 MS61222-S Gas Pressure Washer — 3100 PSI, 2.3 GPM, CRX165 Engine

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Max pressure

2,300 PSI

3,100 PSIBest

Max flow

1.76 GPM

2.3 GPMBest

Cleaning units

—

Hose length

25 ft

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 & Brushless Motor

Driveways, Sidewalks & Heavy Concrete Grime

PSI · GPM · Cleaning Units

2,300 Max PSI · 1.76 Max GPM · 1,900 PSI / 1.24 GPM rated

2,300 Max PSI · 2.3 Max GPM · PWMA Certified

3,100 PSI · 2.3 GPM

Motor / Engine & Pump

120V electric motor · Auto-stop pump

TruBrushless motor · Axial cam pump

CRX165 residential engine · OEM Technologies axial cam pump w/ thermal relief

Hose, Nozzles & Frame

25 ft nylon-braided hose · 5 QC nozzles (0°, 15°, 25°, turbo, soap) · 20 oz soap tank

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

25 ft MorFlex 1/4" hose · 4 QC tips (0°, 15°, 40°, soap) · 16" steel wand

Weight & Power Source

19 lbs · 16.5" tall · 4 × 360° wheels

41.2 lbs (18.7 kg) · 10" wheels · 35 ft GFCI cord

54 lbs · Unleaded gasoline · 12" never-flat wheels

Main Trade-Off

Rated output is 1,900 PSI and 1.24 GPM—well below the max figures—so heavy concrete stains take longer than with a gas washer.

At about 41 lbs (18.7 kg), it is roughly twice as heavy to lift into a trunk as the 19 lb Westinghouse ePX3100.

Requires gas/oil maintenance and winterizing before freezing temperatures; 49-state compliant.

Spec wins

0 / 4Check price on Amazon

1 / 4Check price on Amazon

2 / 4Check price on Amazon

The verdict

SIMPSON Cleaning MegaShot MS61222-S Gas Pressure Washer — 3100 PSI, 2.3 GPM, CRX165 Engine wins 2 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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