PSI to Bar Converter

Turn a psi gauge reading into bar, kPa or atmospheres — tyre placards, boiler gauges and dive cylinders.

Conversion table

Pressure	In bar
1	0.068948 bar
2	0.1379 bar
3	0.20684 bar
4	0.27579 bar
5	0.34474 bar
10	0.68948 bar
15	1.0342 bar
20	1.379 bar
25	1.7237 bar
30	2.0684 bar
40	2.7579 bar
50	3.4474 bar
60	4.1369 bar
70	4.8263 bar
75	5.1711 bar

📌 Numbers worth remembering

1 bar14.5038 psi
1 psi0.068948 bar
1 atm1.01325 bar
32 psi (car tyre)2.21 bar

Getting the tyre number right

Use the placard in the driver's door frame, not the number moulded into the sidewall — the sidewall figure is the maximum the tyre can hold, not the pressure the car wants.
Check cold. Ten minutes of driving warms the air and adds around 0.1 bar (1.5 psi), so a warm tyre reads high and you end up letting good air out.
The two pairs that cover most cars: 32 psi = 2.2 bar and 36 psi = 2.5 bar.
A European gauge marked in kPa is the same scale as bar with the decimal point moved: 220 kPa is 2.2 bar.

What the two units actually are

One psi is the pressure of one pound-force spread over one square inch: 6,894.757 pascals. One bar is defined outright as 100,000 pascals — a round number chosen because it lands within 1.3% of the average air pressure at sea level. That is the whole reason the bar exists: at sea level you are living under roughly one bar, so a boiler at 1.5 bar or a tyre at 2.2 bar is easy to picture. Dividing the two definitions gives the only factor you need: 1 bar = 14.5038 psi.

Why Europe reads bar and the United States reads psi

The pound-force per square inch is an imperial unit that never left American workshops, and every gauge, compressor and tyre placard sold there is printed in it. Continental Europe went metric, and while the strict SI unit for pressure is the pascal, one pascal is a tiny amount of pressure — atmospheric pressure is about 101,325 of them. The bar survived as the practical everyday size, so European door placards, bicycle pumps and heating systems are all marked in bar. Neither scale is more correct; they are just different-sized rulers for the same thing, and the conversion between them is exact.

Gauge pressure: the detail that trips people up

A tyre gauge, a boiler gauge and a dive gauge all read RELATIVE pressure — how much more than the surrounding air. A flat tyre reads zero, yet it still holds about 1 atm inside.
Written properly that is psig (gauge) versus psia (absolute). Add roughly 1 bar to a gauge reading to get the absolute pressure.
It matters for gas laws. A tyre at 2.2 bar on the gauge is really at about 3.2 bar absolute, and that is the figure that scales with temperature.
Weather reports work the other way round: they quote absolute pressure, around 1013 hPa (1.013 bar) at sea level.
1 bar is not 1 atmosphere. One standard atmosphere is 101,325 Pa = 1.01325 bar, so an atm is 1.3% larger.
Vacuum gauges can read below zero on the gauge scale; absolute pressure never goes below zero.

Where each number shows up

Passenger car tyres: 2.0–2.5 bar, which is 29–36 psi. Loaded or towing usually adds 0.2–0.3 bar at the rear.
Road bicycle tyres: 6–8 bar (90–115 psi). Gravel and mountain tyres run far lower, 1.5–3 bar.
Domestic heating systems: 1.0–1.5 bar cold. Below 1 bar the boiler usually locks out and needs topping up.
Scuba cylinders: 200 bar or 300 bar, which are the 3,000 psi and 4,350 psi you see on American gauges.
Espresso machines: 9 bar at the group head, roughly 130 psi.
Car air conditioning and hydraulics are usually quoted in bar in Europe and psi in the US for the same circuit.

Worked examples

Both directions, with the arithmetic shown

A US placard says 32 psi

32 psi × 6,894.757 Pa = 220,632 Pa
220,632 Pa ÷ 100,000 Pa per bar = 2.206 bar
Shortcut: 32 ÷ 14.5038 = 2.21

32 psi = 2.21 bar

A European placard says 2.4 bar

2.4 bar × 14.5038 psi = 34.8 psi
Set a US gauge to 35 psi
Same tyre, same air — only the scale on the dial changed

2.4 bar = 34.8 psi

Frequently Asked Questions

How many bar is 1 psi?

0.068948 bar. The relationship is exact because both units are defined against the pascal: 1 psi = 6,894.757 Pa and 1 bar = 100,000 Pa. In practice, divide psi by 14.5 to get bar, and multiply bar by 14.5 to go back.

What is 32 psi in bar?

2.21 bar. That is the most common car tyre figure in the world, and on a European placard the same car would be printed as 2.2 bar. The other pair worth memorising is 36 psi = 2.48 bar, usually printed as 2.5.

Is 1 bar the same as 1 atmosphere?

No, and the gap is real. One standard atmosphere is defined as 101,325 pascals, so 1 atm = 1.01325 bar — an atmosphere is 1.3% bigger. The bar was chosen as a round 100,000 Pa precisely because it is close to atmospheric pressure without being tied to it.

Does my tyre gauge show absolute pressure?

No. Tyre, boiler and dive gauges all show gauge pressure: the excess over the surrounding air. That is why a completely flat tyre reads zero even though it still contains air at about 1 bar. To get absolute pressure, add roughly 1 bar to whatever the gauge says.

Why does my tyre pressure drop in winter?

Because pressure follows temperature in a sealed volume. A drop of 10 °C takes about 0.1 bar (1.5 psi) out of a car tyre, so the first cold morning of autumn is when TPMS warning lights appear across whole cities. Nothing has leaked; the same air is simply pushing less hard.

Should I use the pressure printed on the tyre sidewall?

No. The sidewall shows the maximum pressure the tyre is rated for, which is a safety limit, not a target. The pressure the car was designed around is on the placard in the driver's door frame or in the manual, and it is usually well below the sidewall figure.