Skip to content

Researched from published specs and owner reviews, not tested in person. As an Amazon Associate we earn from qualifying purchases.

Backyard Gear Calc
Menu

Pressure Washing

Pressure Washer PSI Calculator: PSI, GPM and Nozzle by Surface

Last updated Researched from specs, manuals and owner reviews, not tested in person

Quick answer

Use about 2,500 to 3,000 PSI and at least 2.3 GPM for concrete driveways, 1,500 to 2,500 PSI for brick and pavers, 1,300 to 1,600 PSI for vinyl siding, 1,200 to 1,900 PSI for cars, and only 500 to 1,200 PSI for wood decks and fences. Roofs should be soft washed, not pressure washed.

Pressure is only half of cleaning power. PSI, pounds per square inch, is how hard the water hits; GPM, gallons per minute, is how much water rinses the dirt away. Too much PSI etches wood and strips paver sand; too little GPM makes a driveway an all-afternoon job. Choose the surface, enter the area and your washer's ratings if you own one, and the calculator gives the PSI range, minimum GPM, nozzle tip, working distance and an estimated cleaning time. Every surface has its own page under pressure washer PSI by surface.

Pressure washer PSI calculator

Recommended pressure

2,500 to 3,000 PSI

Pressure washers for this job

Top matches update when you calculate.

On this page
  1. What PSI do I need for each surface?
  2. What do the pressure washer nozzle colors mean?
  3. Is PSI or GPM more important?
  4. How does the calculator estimate cleaning time?
  5. Should I buy an electric or gas pressure washer?

What PSI do I need for each surface?

Pressure washer settings by surface
SurfacePSIGPMNozzleDistance
Concrete driveway2,500 to 3,0002.3+15 or 25 degree, or a surface cleaner8 to 12 in
Pavers1,500 to 2,5002+25 degree or a surface cleaner12 in
Brick1,500 to 2,5001.8+25 degree12 in
Vinyl siding1,300 to 1,6001.5+25 or 40 degree, soap tip for detergent12 to 24 in
Stucco1,200 to 1,5001.5+40 degree18 to 24 in
Wood deck500 to 1,2001.2+40 degree (25 degree only at distance on hardwoods)12 to 18 in
Composite deck1,000 to 1,5001.2+40 degree fan8 to 12 in
Wood fence500 to 1,2001.2+40 degree12 to 18 in
Cars and trucks1,200 to 1,9001.2+40 degree, foam cannon for soap12 to 24 in
Patio furniture500 to 1,5001.2+40 degree12 to 24 in
WindowsSoft wash, under 12001.2+40 degree, at a distance24 or more in
RoofSoft wash, under 5001.2+Soft wash only (low pressure with a roof cleaning solution)from the ground or by a professional

What do the pressure washer nozzle colors mean?

Quick-connect nozzle tips
TipColorUse
0 degreeRedPinpoint blast for stubborn spots on metal or concrete at a distance. Never on wood, siding, vehicles, skin or anything near people and pets.
15 degreeYellowStripping and heavy stains on concrete and masonry. Too aggressive for wood and siding.
25 degreeGreenGeneral cleaning of driveways, brick, pavers, fences and outdoor equipment.
40 degreeWhiteGentle, wide fan for siding, vehicles, windows, softwood decks and patio furniture.
65 degree or soapBlackLow-pressure tip that lets the pump draw detergent. Applies soap; does not clean on its own.

Is PSI or GPM more important?

Both, but for large flat areas GPM matters more than people expect. PSI loosens dirt; GPM carries it away and determines how quickly you cover ground. Multiplying the two gives cleaning units, a rough measure of cleaning power: a 2,000 PSI, 1.2 GPM electric washer produces 2,400 cleaning units, while a 3,400 PSI, 2.6 GPM gas washer produces 8,840, more than three times the work per minute. That is why a gas washer such as the Westinghouse WPX3400 3400 PSI 2.6 GPM Gas Pressure Washer or the Simpson Clean Machine 3400 PSI 2.5 GPM Gas Pressure Washer is the practical choice for driveways and whole-house washing, while a compact electric like the Sun Joe SPX3000 Electric Pressure Washer suits cars, furniture and small decks. The full trade-off is in pressure washer PSI vs GPM.

Cleaning units by washer class
ClassPSIGPMCleaning unitsBest for
Compact electric1,800 to 2,0001.1 to 1.42,000 to 2,800Cars, furniture, small decks
Full-size electric2,300 to 3,0001.2 to 2.02,800 to 6,000Siding, decks, small patios
Residential gas2,800 to 3,4002.3 to 2.66,400 to 8,800Driveways, whole-house washing
Heavy-duty gas3,600 to 4,4002.8 to 4.010,000 to 17,600Large concrete areas, surface cleaners

How does the calculator estimate cleaning time?

Cleaning time here is a rough planning estimate: square feet per minute = GPM x a surface factor, about 3 for concrete with a wand, 4 for siding and 5 for vehicles, reflecting how much scrubbing each surface needs. A rotary surface cleaner is estimated at about four times the wand rate on flat concrete and pavers. A 2.5 GPM gas washer with a wand covers roughly 7.5 square feet a minute of driveway, so a 600 square foot driveway takes about 80 minutes with a wand and about 20 minutes with a surface cleaner such as the Westinghouse 15 in. Pressure Washer Surface Cleaner. Heavy staining, mildew and detergent dwell time add to any estimate.

Should I buy an electric or gas pressure washer?

Choose electric for cars, patio furniture, decks and occasional siding: electric washers are quiet, start instantly, need no engine maintenance and their 1,200 to 2,000 PSI is safer on soft surfaces. The Greenworks 3000 PSI 2.0 GPM Brushless Electric Pressure Washer pushes electric into 2.0 GPM territory. Choose gas for concrete, large patios, long fences and whole-house washing, where 2.5 GPM or more and a surface cleaner save hours; the Simpson PowerShot 4400 PSI 4.0 GPM Gas Pressure Washer at 4.0 GPM is the heavy-duty end. Compare in electric vs gas pressure washers, and see tiered picks in the best pressure washers.

Frequently asked questions

What PSI is best for washing a house?

For vinyl siding, about 1,300 to 1,600 PSI with a 25 or 40 degree tip, used 12 to 24 inches from the surface, is the common guidance. Apply house wash detergent through the soap tip first, let it dwell, then rinse working level or downward so water does not get forced up under the siding laps. Stucco and painted wood need even lower pressure or soft washing.

Is 2000 PSI enough to clean concrete?

It will clean concrete, but slowly, especially with the low 1.1 to 1.4 GPM typical of 2,000 PSI electric washers. For driveways, 2,500 to 3,000 PSI with 2.3 GPM or more and a rotary surface cleaner is far faster and more even. If you only clean a small patio occasionally, a 2,000 PSI electric with a small surface cleaner attachment can be enough.

What PSI should I use on a wood deck?

Use about 500 to 800 PSI on softwoods such as pine and cedar and up to about 1,200 PSI on dense hardwoods, with a 40 degree tip held 12 to 18 inches away and moved with the grain. Too much pressure or too close a tip gouges wood and raises fibers that then need sanding. Composite decks follow their maker's care guide, and some makers restrict pressure washing.

Can you pressure wash a roof?

Pressure washing asphalt shingle roofs is widely discouraged because high pressure strips the protective granules, can shorten shingle life and may void warranties. Roofs are cleaned by soft washing, which uses low pressure and a roof cleaning solution. Working on a roof or ladder with a pressure washer is dangerous, so roof cleaning is a job for a professional service.

How many GPM do I need in a pressure washer?

For cars, furniture and small decks, 1.2 to 1.5 GPM is enough. For siding and larger decks, 1.5 to 2.0 GPM makes rinsing faster. For concrete driveways, patios and surface cleaners, look for 2.3 GPM or more; most surface cleaners list a minimum flow. Higher GPM also needs a water supply that can keep up, so check your spigot flow with a bucket and a timer.

Researched, not professional advice. This page is compiled from published specifications, manuals, labels and owner-review consensus, not hands-on testing. Follow the manufacturer's instructions and product label, and consult a qualified professional where safety, chemicals, fuel or structures are involved. As an Amazon Associate we earn from qualifying purchases.