Convert pressure between psi, bar, atmospheres, kilopascals, pascals and mmHg — with exact factors.
What Is a Pressure Converter?
A pressure converter translates between the pressure units of different worlds: 1 atmosphere = 101.325 kPa = 14.696 psi = 760 mmHg. Tyre gauges read psi, weather reports use hPa (= mbar), scuba and industry use bar, and science uses the pascal (1 newton per square metre). The atmosphere is defined from standard sea-level pressure; the bar is a clean 100,000 Pa; the psi is the imperial survivor.
How to Use
- Enter the value.
- Pick the “from” unit.
- Pick the “to” unit.
- Click “Convert Pressure”.
Formula
Convert to pascals first (value × from-factor), then divide by the to-factor. All factors are exact definitions.
Worked Example
1 atm → kPa: 101,325 ÷ 1,000 = 101.325 kPa. And 1 bar → psi: 100,000 ÷ 6,894.757293168 = 14.5038 psi.
How It Works, In Plain Words
Each unit is stored as its value in pascals: the pascal itself is 1, the kilopascal 1,000, the bar 100,000, the psi 6,894.757293168, the atmosphere 101,325 and the mmHg 133.322387415. The tool multiplies your value by the from-factor to reach pascals, then divides by the to-factor — exactly the two steps the worked example prints for 1 atm becoming 101,325 ÷ 1,000 = 101.325 kPa, and for 1 bar becoming 100,000 ÷ 6,894.757293168 = 14.5038 psi. Because every unit funnels through pascals, all six pairings stay consistent with each other.
The introduction’s headline row is the same machinery read three ways: 1 atmosphere = 101.325 kPa = 14.696 psi = 760 mmHg. The pascal is the science unit — 1 newton per square metre — and the introduction explains where the others come from: the atmosphere from standard sea-level pressure, the bar as a clean 100,000 Pa, and the psi as the imperial survivor. Results are shown to four decimal places, so the mmHg factor keeps its precision instead of rounding a small pressure away to nothing.
Real-World Uses
A driver whose door sticker quotes kilopascals but whose gauge reads psi converts the recommendation across before topping up — the FAQ works the same problem in bar, finding 32 psi to be about 2.21 bar. A weather watcher comparing a forecast in hPa, which the introduction notes equals mbar, with a barometer marked in mmHg uses the 760 mmHg atmosphere as the bridge between the two scales. A scuba diver or technician moving between the bar of scuba and industry and the psi of an imported gauge converts cylinder and line pressures without mixing the two systems up. In each case the number only means something once its unit is translated. The converter’s six units cover the gauges most people actually meet.
Benefits
- Six units covering tyres, weather, diving and science
- Exact defined factors
- Both directions in one tool
- The atm/psi/bar triangle explained
Features of Our Tool
- Instant results in your browser
- No sign-up, no download, 100% free
- Works on mobile, tablet and desktop
- Clear step-by-step explanation below the tool
- Private — your entries never leave your device
Common Mistakes
- Confusing bar with atm — close (1.01325 bar = 1 atm) but not equal
- Reading gauge vs absolute pressure: tyre gauges read above atmospheric; mixing them up misleads
- Using psi for weather or hPa for tyres — right number, wrong unit convention
Common Mistakes to Avoid
The first mistake is treating bar and atm as interchangeable: the list warns they are close — 1.01325 bar = 1 atm — but not equal, and the FAQ repeats that they come from different definitions, sea-level pressure versus 100,000 Pa. The second is mixing gauge and absolute pressure, since the list notes that tyre gauges read above atmospheric; comparing a gauge reading with an absolute specification misleads by a whole atmosphere. The third is using the right number in the wrong convention — psi for weather or hPa for tyres, as the list puts it. Check which unit your gauge, report or manual actually uses before converting anything. It takes seconds and prevents the commonest errors on this page.
FAQ
How many kPa is 1 atm?
101.325 kPa.
How many psi is 1 bar?
14.5038 psi.
What is the difference between bar and atm?
1 atm = 1.01325 bar — very close, from different definitions (sea-level pressure vs 100,000 Pa).
What is mmHg?
Millimetres of mercury — 760 mmHg = 1 atm; still used in medicine and vacuum work.
What tyre pressure in bar is 32 psi?
About 2.21 bar (32 ÷ 14.5038).
Is hPa the same as mbar?
Yes — the introduction notes that weather reports use hPa (= mbar). To convert a weather reading into this tool’s units, remember the atmosphere row: 1 atmosphere = 101.325 kPa = 760 mmHg.
Why does the tool route everything through pascals?
So that all six units stay consistent, as the formula section explains: your value is multiplied by its from-factor into pascals, then divided by the to-factor — the worked example shows 101,325 ÷ 1,000 for atmospheres to kilopascals.