What does PSI stand for?

PSI stands for Pounds per Square Inch. It measures pressure as the force in pounds applied to one square inch of area. Normal atmospheric pressure at sea level is about 14.7 PSI.

What is a good tire pressure in PSI?

Most passenger car tires should be inflated to 30-35 PSI, though the correct pressure varies by vehicle. Check the sticker on the driver's door jamb or your owner's manual for the manufacturer's recommendation.

What is normal water pressure in PSI?

Normal household water pressure ranges from 40-80 PSI, with 50-60 PSI being ideal. Below 40 PSI feels weak; above 80 PSI can damage plumbing fixtures.

What Is PSI? Pounds per Square Inch Explained

Definition

PSI (pounds per square inch) is a unit of pressure in the imperial system. It measures the force in pounds exerted on an area of one square inch:

1 PSI = 1 lbf/in² = 6,894.76 Pa ≈ 0.0689 bar

PSI Conversions

Unit	1 PSI Equals
Pascals	6,894.76
Bar	0.0689
Atmospheres	0.0681
mmHg	51.715
kPa	6.895

Common PSI Values

Application	Typical PSI
Atmospheric pressure (sea level)	14.7
Car tire	30-35
Bicycle tire (road)	80-130
Mountain bike tire	25-40
Home water pressure	40-80
Pressure washer	1,000-4,000
Scuba tank	2,500-3,500
Hydraulic system	1,500-5,000

PSI Variants

PSIA (PSI Absolute): Measured relative to a perfect vacuum. Atmospheric pressure = 14.7 PSIA.
PSIG (PSI Gauge): Measured relative to atmospheric pressure. A tire at 32 PSIG is actually at 46.7 PSIA.
PSID (PSI Differential): The difference in pressure between two points.

Where PSI Is Used

Tire Maintenance

Proper tire inflation in PSI affects safety, fuel economy, and tire longevity. Under-inflation causes poor handling and increased wear; over-inflation reduces traction.

Plumbing

Water pressure regulators are set in PSI. Most homes need a pressure-reducing valve if supply pressure exceeds 80 PSI to protect fixtures and appliances.

Convert pressures with our pressure converter.