The PSI stands for "Pounds per Square Inch," and is the common unit of measurement for pressure. It can be understood as the amount of force that is exerted on an area of one square inch. Normal atmospheric pressure at sea level is 14.7 PSI. Also called PSIG for pounds per square inch gauge. In the USA the PSI pressure unit is the primary unit of measure for pressure and almost all pressure instruments are specified and display in pounds per square inch. The PSI is still used extensively in the UK but the bar pressure unit has mostly replaced it as the primary pressure unit.

To convert a reading in PSI to another unit multiply it by the relevant pressure conversion factor. To convert a reading in any pressure unit to PSI divide it by the relevant pressure conversion factor. If your need require use of the power washing equipment for more than 100 hours per year, you will need to go for a commercial or industrial power washer, usually starting at 2000 PSI and 3GPM and up, as they are designed to sustain intensive use. Hence PSI is the measurable unit of pressure in Power Washers. At Power-Washing.org you will get more information on Power washers