Pressure Converter (bar, psi, kPa, atm)
Bar to psi, kPa to atmospheres — tyre pressures, weather charts and engineering figures, converted exactly.
Fast, easy and free — your answer appears as you type, and whatever you enter stays on your device.
Bar to psi, kPa to atmospheres, mmHg to pascals — typed into either side, converted exactly, with the factor shown. The bar-psi pair alone covers most real life: tyre pressures on holiday.
How to use it
- Pick the unitsBar and psi are preloaded — the tyre-pressure pair. Five other units cover weather, medicine and engineering.
- Type the valueThe answer appears as you type; Swap flips the direction.
- Check the factorThe exact multiplier is printed under the answer.
Seven units, four worlds
Pressure units cluster by profession. Drivers meet bar and psi at the tyre pump. Medicine runs on mmHg. Meteorology speaks hectopascals — millibars in older broadcasts, the same number exactly. Engineering uses pascals and their multiples because they are the SI unit that plays cleanly with newtons and metres. Nobody needs all seven daily; everybody eventually needs a bridge between two of them, usually standing at an air pump abroad.
Anchors worth carrying
Sea-level air pressure is the master anchor: about 1 bar, 1 atm, 14.7 psi, 1013 hPa and 760 mmHg — all the same physical fact in five dialects. From there, useful landmarks: car tyres 2.2–2.9 bar (32–42 psi), road-bike tyres far higher at 6–8 bar, an espresso machine about 9 bar, a champagne bottle roughly 6. Knowing two anchors makes any figure you meet instantly checkable, which is most of what unit fluency is.
Values stay on your device, and the tool keeps working with no connection.
Questions people ask
What is 2.4 bar in psi?
About 34.8 psi — typical car tyre territory. The quick mental rule: bar × 14.5 ≈ psi, so 2.2 bar ≈ 32 psi and 2.9 bar ≈ 42 psi. European placards quote bar, most gauges sold worldwide read psi, and this pair is the tool's default for that reason.
How exact are these conversions?
Fully exact. The bar is defined as exactly 100,000 pascals and the standard atmosphere as exactly 101,325 Pa. The psi derives from the exactly-defined pound-force and inch — 6,894.757 Pa. Only the displayed answer is rounded.
What is the difference between bar and atmosphere?
About 1.3% — one atmosphere is 1.01325 bar. The bar was deliberately defined as a round number close to sea-level air pressure, which is why the two are casually interchangeable in conversation and must not be in engineering.
Where is mmHg used?
Blood pressure, almost universally — 120/80 is millimetres of mercury — and some vacuum and weather contexts. One mmHg is 133.322 Pa, a value with the mercury column of early barometers fossilised inside it.
Weather maps say hPa — where is that here?
A hectopascal is exactly 100 Pa, and it equals the older millibar precisely: the 1013 hPa on a forecast is 1.013 bar. Convert via the kPa entry (1 kPa = 10 hPa) or read bar values × 1000.
Is anything I enter stored?
No — everything runs on your device and works offline once loaded.