Tyre Pressure Converter

The conversion used

1 bar equals exactly 100 kPa, and 1 psi equals 6.894757 kPa (equivalently, 1 bar equals 14.5038 psi). These are exact defined values, so the numbers here match any correctly calibrated gauge; there is no rounding assumption hidden in the arithmetic.

Why three units exist on the same valve cap

Psi is the imperial gauge unit and what most UK and US forecourt pumps and tyre gauges default to. Bar is the metric unit most European vehicle handbooks and door-placard stickers use, and is close enough to atmospheric pressure (1.01325 bar) that it's an intuitive round number. Kilopascals are the SI unit and appear on some European and Japanese placards and TPMS displays. All three describe the same physical pressure; a tyre at 32 psi is exactly 2.2 bar, no conversion guesswork required.

Cold pressure is the number that matters

Every placard and handbook figure assumes a cold tyre, meaning the car hasn't been driven for at least a few hours, or was driven under two miles at low speed. Driving heats the air inside the tyre and raises the reading by roughly 0.2 to 0.3 bar (3 to 4 psi) after twenty minutes on the motorway, which is normal and not a sign of overinflation. Always compare against the placard figure using a cold reading, and reset it cold as well.

What this tool doesn't do

It converts between units; it does not tell you the correct pressure for your vehicle. That figure is set by the manufacturer for a specific tyre size and load, and is printed on the door pillar, fuel flap or in the handbook, not calculated from tyre dimensions. Loaded, towing and space-saver spare pressures are usually higher than the standard placard figure and are listed separately where they apply. If you've changed tyre size, check the fitment first with the tyre size comparator, pressure and size are separate checks.