Pressure Washers Buying Guide: PSI, GPM, and What Actually Matters

Understanding PSI and GPM

PSI measures pressure, GPM measures volume.

A washer with high PSI but low GPM sprays a forceful but narrow stream, while high GPM at moderate PSI covers more surface area per minute.

For most cleaning tasks, the combination matters more than either number alone.

The Greenworks Pro 2300 PSI, at 2300 PSI and 2.3 GPM, clears a driveway faster than a hypothetical higher-PSI machine with a much lower GPM, because it's moving more total water across the surface.

Electric vs. Gas

Electric pressure washers, like the Sun Joe SPX3000, Karcher K5 Premium, and Greenworks Pro 2300 PSI, cover PSI ranges from about 1500 up to 2300, plug into a standard outlet, and need no ongoing maintenance beyond basic care.

Gas pressure washers, like the Simpson MegaShot, start w here electric tops out, typically 2800 PSI and up, and are the better choice for large properties, heavy oil-sta in removal, or locations without power access.

The tradeoff is fuel, oil, seasonal storage prep, and significantly more noise.

Motor Types and Durability

Standard brushed motors are the default in budget electric units and hold up fine for occasional, seasonal use.

Brushless motors, like Greenworks' TruBrushless design, and water-cooled induction motors, like Karcher's, are built for quieter operation and a longer service life under frequent use, generally justifying their higher price for anyone using a pressure washer regularly across multiple seasons.

Nozzle Kits and Fittings

A useful nozzle kit includes a narrow tip (0 or 15-degree) for tough concrete stains, a mid-range tip (25-degree) for general use, a wide fan tip (40-degree) for delicate surfaces like wood and paint, and a dedicated soap nozzle for detergent application.

Standard quick-connect fittings, used by Sun Joe, Karcher, and Greenworks models, offer the widest compatibility with aftermarket foam cannons and surface cleaners.

Bayonet-style fittings, like those on the AR Blue Clean AR383, work fine with included accessories but may need an adapter for some third-party attachments.

Detergent Systems

A single onboard tank covers most needs.

Dual removable tanks, found on the Sun Joe SPX3000 and SPX3001, are worth prioritizing if you regularly switch between an all-purpose cleaner and a degreaser for oil stains.

Final Recommendation Framework

Start with your primary task (driveway, deck, cars, or small jobs) to set a PSI target, then pick electric unless you have a specific reason to need gas-level pressure, then let your budget determine motor type and convenience features like an adjustable wand or dual detergent tanks.