Shopping for a pressure washer, a versatile tool for household cleaning and maintenance projects, may be overwhelming especially when faced with unfamiliar specs like GPM and PSI. Higher PSI increases your ability to blast through stubborn grime, remove paint, and dislodge stuck-on debris. For regular concrete cleaning and large surface areas, invest in higher GPM even if it means slightly lower PSI. Putting your thumb over its nozzle releases slightly less water (GPM), but at a higher pressure (PSI). For instance, a machine with 2000 PSI and 2.0 GPM produces 4000 cleaning units, while a machine with 1500 PSI and 3.0 GPM produces 4500 cleaning units.