Bar to PSI Converter
Instantly convert bar to PSI for tyre pressure, air tools and compressor settings. Covers the pressures you actually look up, from car tyres to road bike tubes.
Last updated: June 2026
Enter a value to see the conversion instantly.
Real-world pressure reference
Car tyres: Most passenger cars run at 2.0-2.5 bar (29-36 PSI). The exact value is printed on a sticker inside the driver's door frame or on the fuel cap, not the maximum pressure moulded into the tyre sidewall, which is the tyre's structural limit, not the recommended running pressure.
Bicycle tyres: Road bikes typically run at 7-9 bar (100-130 PSI). Mountain bikes run much lower at 1.5-2.5 bar (22-36 PSI) for grip on loose terrain. City and hybrid tyres sit between 4-6 bar (58-87 PSI). Always check the sidewall of the specific tyre for its rated range.
Workshop compressors: Most portable compressors deliver 8-10 bar (116-145 PSI). European equipment is typically labelled in bar; US-spec gauges show PSI. The formula is PSI = bar × 14.503774.
Tyre and compressor pressure reference table
| bar | PSI | Typical use |
|---|---|---|
| 1.5 | 21.76 | Mountain bike tyre |
| 2.0 | 29.01 | Car tyre (lower limit) |
| 2.5 | 36.26 | Car tyre (typical) |
| 3.0 | 43.51 | Car tyre / SUV (upper limit) |
| 5.0 | 72.52 | City or hybrid bike |
| 7.0 | 101.53 | Road bike tyre (low end) |
| 9.0 | 130.53 | Road bike tyre (high end) |
| 10.0 | 145.04 | Compressor output (typical max) |
How temperature changes tyre pressure
Tyre pressure is not fixed: it rises and falls with temperature. As a rule of thumb, pressure changes by about 1 PSI (0.07 bar) for every 10 °F, or roughly 5.5 °C, of temperature change. A tyre set to 2.5 bar (36 PSI) on a warm afternoon can read noticeably lower on a cold morning, which is why a tyre-pressure warning light often appears after the first cold night of autumn.
Two practical habits follow. First, always set pressure when the tyres are cold, meaning before driving or at least a few hours after, because friction heats the air inside and can inflate the reading by 2 to 4 PSI. Second, recheck pressures when the seasons turn: a 20 °C swing between summer and winter is enough to move a tyre well outside its recommended range.
Frequently Asked Questions
What is the correct tyre pressure for a car in bar?
Most passenger cars need 2.0 to 2.5 bar (29-36 PSI), but the exact figure depends on the vehicle and load. Check the sticker inside the driver's door frame, the glovebox, or the fuel cap. Do not use the maximum pressure moulded into the tyre sidewall, that is the tyre's structural limit, not the recommended running pressure.
What bar pressure do road bike and mountain bike tyres use?
Road bike tyres typically run at 7-9 bar (100-130 PSI). Mountain bike tyres run much lower, around 1.5-2.5 bar (22-36 PSI), to improve grip on loose or technical terrain. Hybrid and city bike tyres usually sit at 4-6 bar (58-87 PSI). Always check the rated range printed on the tyre sidewall, as it varies by brand and model.
Can I round bar or PSI values?
For general workshop use, rounding to one decimal place is usually fine. For tyres, stay within 0.1 bar (1-2 PSI) of the recommended value. Over-inflated tyres reduce grip; under-inflated tyres increase rolling resistance and risk sidewall damage. Regulated systems like hydraulics or industrial equipment require the exact values from the manufacturer's spec sheet.
My compressor shows bar but my gauge reads PSI, how do I convert quickly?
Multiply bar by 14.5 for a quick estimate, or use this converter for the exact value. A compressor set to 8 bar outputs approximately 116 PSI. Most dual-scale gauges show both units, but if yours does not, the rule of thumb (bar × 14.5) is close enough for most workshop tasks.
Why does the converter start at 2.5 bar?
2.5 bar (36.26 PSI) is the typical front tyre pressure for a mid-size passenger car. It is the single most common value people look up when checking whether their pump gauge matches the sticker in the car door, so starting there gives an immediately useful reference rather than an abstract 1 bar default.
Why does my tyre pressure warning light come on when it gets cold?
Air pressure drops as temperature falls, by roughly 1 PSI (0.07 bar) for every 10 °F or 5.5 °C. After the first cold night of the season, a tyre that was correctly set in warm weather can fall below the threshold that triggers the warning. Top it up to the recommended cold pressure and the light usually clears.