Start from the job, not the biggest PSI badge
Pressure washer marketing leads with PSI. Flow (GPM) decides how fast you rinse. Cleaning Units (CU) = PSI × GPM is the simple product used by rental fleets and tool reviews to compare total cleaning power. WashPSI maps your job to a minimum CU and a maximum PSI, then matches a verified VEVOR US consumer ladder.
Job codes used on this site
1 vehicles / soft wash (≥2500 CU, ≤2100 PSI) · 2 patio furniture / light siding (≥3500 CU, ≤2100 PSI) · 3 wood deck / fence (≥5000 CU, ≤3600 PSI) · 4 concrete driveway / brick patio (≥8000 CU, ≤3600 PSI) · 5 heavy paint / tough concrete (≥14000 CU, ≤4500 PSI) · 6 commercial continuous (≥20000 CU). Soft jobs stay on electric so a 3400+ PSI gas unit is not forced onto paint.
Published consumer class ladder
WashPSI maps jobs to three verified VEVOR US classes: electric 2000 PSI × 1.76 GPM = 3520 CU, gas 3400 PSI × 2.6 GPM = 8840 CU, and gas 4400 PSI × 4.0 GPM = 17600 CU. The smallest class that clears both the CU floor and the PSI cap is shown. Job 6 returns NO_MATCH instead of recommending an undersized homeowner unit.
Soft surfaces still need technique
Even a matched electric class can etch paint or force water past seals if you use a 0° tip or stand too close. Prefer a wide fan tip, keep standoff, and test a hidden corner. Sources reviewed for this methodology include Popular Mechanics and United Rentals guidance on PSI versus GPM and CU comparisons, plus Pro Tool Reviews explanations of Cleaning Units.
Limits and honesty rules
This screen does not size nozzles, foam cannons, or hot-water commercial systems. Affiliate tracking is pending. Product links are ordinary VEVOR merchant URLs checked on 2026-09-10; availability can change. A matched class is not a surface warranty.