What pressure washer PSI do you need? PSI tells you how hard the water hits, but it is only half the story. GPM (gallons per minute) tells you how much water does the work, and multiplying the two gives cleaning units, the best single number for comparing machines. For washing a car, a lower pressure electric machine with a wide fan nozzle is the safer choice. For concrete, fleets and heavy grease, you want more PSI and more GPM, and sometimes hot water. This guide compares real machines from our catalog so you can match the numbers to your job.
Pressure washer PSI, GPM and cleaning units explained
Three numbers show up on every spec sheet. Here is what each one means for you.
- PSI (pounds per square inch): the force of the spray. Higher PSI breaks stronger bonds, like dried mud, oil stains, or old paint chalk.
- GPM (gallons per minute): the water flow. More GPM rinses away loosened dirt faster and covers more area per pass.
- Cleaning units (CU): PSI multiplied by GPM. The Ferguson pressure washer buying guide describes CU as the true measure of cleaning speed, and notes that a 4 GPM machine cleans about twice as fast as a 2 GPM machine at the same pressure.
That is why a 2,000 PSI machine at 3.5 GPM can outwork a 3,000 PSI machine at 2.5 GPM on a big driveway. High PSI with low flow strips a narrow line. Moderate PSI with high flow clears a wide path and rinses it clean.
Pressure washer comparison table
Specs below come from our product listings. Prices were listed at the time of writing and can change, and freight costs can vary by destination.
| Model | PSI | GPM | Cleaning units | Power | Price |
|---|---|---|---|---|---|
| Kranzle 1122 TST | 1,400 | 2.1 | 2,940 | Electric, 110V, 15A induction motor | About $1,522 |
| Kranzle 2020 PMUSR shelf mount | 2,000 | 1.9 | 3,800 | Electric, 110V, 20A | About $5,508 |
| Dirt Killer H200 | 2,000 | 3.5 | 7,000 | Gas, Honda 5.5 HP | About $1,875 |
| Dirt Killer H357 | 3,000 | 2.5 | 7,500 | Gas, Honda 5.5 HP | About $1,975 |
| BE v7 gas | 3,100 | 2.5 | 7,750 | Gas, Power Ease 7 HP | About $525 |
| Dirt Killer H260 | 2,600 | 3.5 | 9,100 | Gas, Honda 6.5 HP | About $2,099 |
| Dirt Killer H360 | 3,500 | 4.2 | 14,700 | Gas, Honda 13 HP | About $2,500 |
| Hot water commercial, RATO engine | 4,000 | 4.0 | 16,000 | Gas, RATO 15 HP, diesel burner | About $3,549 |
| Hot water commercial, Kohler engine | 4,000 | 4.0 | 16,000 | Gas, Kohler CH440 14 HP, diesel burner | About $4,056 |
Note how the H200 and H357 land close in cleaning units even though one has 1,000 more PSI. Pick the one whose balance fits your surfaces: more flow for rinsing large areas, more pressure for stubborn stains.
Electric vs gas pressure washer
Ferguson sums up the tradeoff well: electric units are lighter, quieter and simpler, while gas units are more powerful, last longer, and can be repaired part by part. Our listings follow the same pattern.
When electric makes sense
The Kranzle 1122 TST runs on a standard 110V, 15 amp circuit with an induction motor, and the listing describes it as built for car detailers and homeowners. The Kranzle 2020 PMUSR is a wall or shelf mounted 110V, 20 amp machine with a 65 foot hose reel, aimed at detail shops that wash cars all day. Electric machines make no exhaust, so they suit garages and wash bays where a gas engine cannot run.
When gas makes sense
If you clean driveways, siding, equipment or fleets, gas gives you more cleaning units and no cord. The Dirt Killer H series pairs Honda engines with Kranzle pumps, and the listings note those pumps are self priming and can run in bypass. The BE v7 is the budget pick: its listing calls it an entry level commercial machine with a brass manifold axial pump rated for 75 to 100 hours. Ferguson notes that axial pumps suit occasional use, so if you will run it weekly for years, the H series is the sturdier path.
Pressure washer for car washing
Car paint and clear coat do not need high pressure. Too much PSI, a narrow tip, or holding the wand too close can damage paint, trim, badges and seals. For a pressure washer for car use, focus on:
- A lower PSI electric machine such as the 1122 TST, or a pro bay unit like the 2020 PMUSR, which ships with a foam cannon.
- A wide fan nozzle, held well back from the panel, moving closer only if the finish handles it.
- Soap first, then a gentle rinse. Let the detergent do the heavy work.
The same caution applies to soft wood decks, cedar siding and outdoor furniture. A tight high pressure stream can raise the grain and gouge the surface, so test on a hidden spot first.
Hot water vs cold water pressure washer
Cold water handles dirt, mud and most home cleaning. Hot water shines on grease, oil and food residue, the kind of buildup you find on shop floors, restaurant pads, and heavy equipment. Both hot water units in the table list a water temperature range up to 212 degrees F, a 6 gallon heating boiler, and diesel burner fuel use of about 1.6 gallons per hour. Factor in that fuel cost and the extra weight before you buy. The Kranzle electric models accept hot water up to 140 degrees F from a supply line, per the 2020 PMUSR listing, but they do not heat it themselves.
Hoses and accessories
Match your hose rating to your machine. Our Dirt Killer single wire 50 ft hose is rated for 4,000 PSI machines, and the double wire version is rated for 6,000 PSI. If you are also sizing an air tool setup for the same garage, our air compressor size guide walks through PSI and CFM in the same way. A solid garage workbench gives you a place to store nozzles, lances and chemicals off the floor. Browse every Dirt Killer pressure washer we carry.
Pressure washer safety
A pressure washer can cause serious injuries. The CDC’s pressure washer safety guidance warns that high pressure spray can cause wounds that look minor at first but need prompt medical care. Follow these rules every time:
- Never point the wand at yourself, other people or pets, and keep children away from the machine.
- Wear eye protection and closed toe shoes.
- Run gas engines outdoors only. The CDC says never inside or in partly enclosed spaces, and at least 20 feet from windows, doors and vents, because of carbon monoxide.
- Plug electric units into a GFCI protected, grounded outlet and test the GFCI before each use. Keep cord connections out of standing water.
- Read the manual for your exact machine. For new hard plumbed wash bays, dedicated circuits or fuel storage, a licensed electrician or plumber and your local code have the final word.
Generators raise the same exhaust concerns, which we cover in solar generator vs gas generator.
Frequently asked questions
Is higher pressure washer PSI always better?
No. More PSI helps with stubborn stains but raises the risk of damaging paint, wood and seals. For overall cleaning speed, compare cleaning units (PSI x GPM), not PSI alone.
What does GPM mean on a pressure washer?
GPM is gallons per minute, the water flow. Higher GPM rinses faster and covers more area, which is why the 4.2 GPM H360 cleans much faster than a 2.5 GPM unit.
What is the best pressure washer for car detailing?
A lower PSI electric machine with a wide fan tip. The Kranzle 1122 TST (1,400 PSI, 2.1 GPM) suits home detailing, and the 2020 PMUSR suits busy detail shops.
Do I need a hot water pressure washer?
Only if you regularly clean grease or oil. For dirt, mud and mildew on a home, a cold water gas or electric unit is usually enough and costs less to run.
Have questions about which machine fits your job? Call us at 866-777-2590, Monday to Friday, 9AM to 6PM PST. We offer free freight shipping on orders of $999 or more, and a $200 flat rate below that. Please review our return and refund policy before you order.
