Pressure Converter
Type a number once — see it in all 10 pressure units instantly.
Enter a number to see it in every pressure unit.
All units at once
| Unit | Value |
|---|---|
| Pascal (Pa) | — |
| Kilopascal (kPa) | — |
| Megapascal (MPa) | — |
| Bar (bar) | — |
| Pound per square inch (psi) | — |
| Standard atmosphere (atm) | — |
| Millimeter of mercury (mmHg) | — |
| Inch of mercury (inHg) | — |
| Hectopascal / millibar (hPa, mbar) | — |
| Kilogram-force per square centimeter (kgf/cm²) | — |
| Inch of water column (inH2O) | — |
| Centimeter of water column (cmH2O) | — |
One base unit, eight everyday pressure units
Pressure conversion works the same way as length or weight conversion: express every unit in terms of one base unit — the pascal (Pa), the SI unit of pressure — and any conversion becomes multiply-then-divide. This tool converts among eight units that show up across engineering, meteorology, automotive and medical contexts: pascal, kilopascal, megapascal, bar, psi, standard atmosphere, millimeter of mercury (mmHg / Torr), and inch of mercury.
A pascal is a very small unit — one newton of force spread over one square meter — so most everyday pressures are reported in kilopascals, bar, psi, or atmospheres instead. This converter shows all eight at once so you can read across scales instantly, whether you are checking a tire gauge in psi or a weather report in hPa (numerically identical to kPa).
The conversion factors
Each unit's value in pascals is shown below. To convert, multiply the input by its factor to get pascals, then divide by the target unit's factor.
| Unit | Pascals per unit |
|---|---|
| Pascal (Pa) | 1 |
| Kilopascal (kPa) | 1,000 |
| Megapascal (MPa) | 1,000,000 |
| Bar (bar) | 100,000 |
| Pound per square inch (psi) | 6,894.757293168 |
| Standard atmosphere (atm) | 101,325 (exact) |
| Millimeter of mercury (mmHg) | 133.322387415 |
| Inch of mercury (inHg) | 3,386.389 |
Worked example 1 — a 32 psi tire in kPa and bar
32 psi × 6,894.757293168 = 220,632.23 Pa. Divide by 1,000 for kilopascals: ≈ 220.6 kPa. Divide by 100,000 for bar: ≈ 2.206 bar. This is a common passenger-car cold tire pressure, though the exact recommended value is always the sticker inside the driver's door, not a number to guess.
Worked example 2 — one standard atmosphere in every unit
1 atm is defined as exactly 101,325 Pa. That is 101.325 kPa, 1.01325 bar, 101,325 ÷ 6,894.757293168 ≈ 14.6959 psi, and exactly 760 mmHg — the reference pressure used to define "standard conditions" in chemistry and aviation altimetry.
Worked example 3 — a 120/80 mmHg blood pressure reading in kPa
120 mmHg × 133.322387415 = 15,998.7 Pa ≈ 16.0 kPa (systolic). 80 mmHg × 133.322387415 = 10,665.8 Pa ≈ 10.7 kPa (diastolic). Millimeters of mercury survive in medicine purely by convention, from the era of mercury-column sphygmomanometers and barometers — this is a unit conversion, not a clinical interpretation of the reading.
Gauge pressure vs. absolute pressure
Most everyday pressure readings — tire gauges, blood pressure cuffs, and household air compressors — are gauge pressure: pressure measured relative to the surrounding atmosphere, which reads zero at normal atmospheric conditions. Absolute pressure is measured relative to a true vacuum, so it equals gauge pressure plus atmospheric pressure (about 101.325 kPa at sea level). This converter performs a pure unit conversion and does not add or subtract atmospheric pressure — if your source value is a gauge reading, the converted value is the same kind of gauge reading in the new unit.
Precision and rounding
- Conversions between metric pressure units (Pa ↔ kPa ↔ MPa ↔ bar) are exact decimal shifts.
- psi, atm, mmHg and inHg use internationally standardized conversion factors (consistent with NIST Special Publication 811), so results are precise, not rough estimates.
- The tool keeps up to 10 significant figures internally and trims trailing zeros for display; very large or very small results fall back to scientific notation instead of rounding to zero.
Where each unit shows up
Knowing where a unit is normally used helps catch typos and unit-mix-ups. Pascals and kilopascals dominate SI engineering specs and weather charts (as hectopascals, numerically equal to kPa). Bar and its cousin the millibar are common in Europe for tire pressure and diving. Psi is standard in the US and UK for tires, plumbing, and compressed gas. Atmospheres describe standard reference conditions in chemistry and high-altitude physiology. mmHg and inHg persist in medicine (blood pressure) and meteorology (barometric pressure) respectively, for historical reasons tied to mercury-column instruments.
Related conversions
This tool covers pressure only. For other everyday conversions — length, weight, temperature, volume and area — visit the Toolhub home, where the matching converters live alongside this one, all free and ad-light.
Sources & further reading
Frequently asked questions
How do I convert psi to bar?
Divide the psi value by 14.5038 to get bar, or multiply by 0.0689476. For example, a common car tire pressure of 32 psi equals 32 × 0.0689476 ≈ 2.206 bar (about 220.6 kPa). The reverse works the same way: multiply bar by 14.5038 to get psi, so 2 bar ≈ 29.008 psi.
What is standard atmospheric pressure in different units?
One standard atmosphere (1 atm) is defined as exactly 101,325 pascals. That equals 101.325 kPa, 1.01325 bar, about 14.6959 psi, and exactly 760 mmHg — the classic sea-level reference used in weather, aviation, and chemistry.
What is a typical car tire pressure in kPa and bar?
Most passenger car tires are inflated to somewhere between 30 and 35 psi, which works out to roughly 207–241 kPa or 2.07–2.41 bar. A common example is 32 psi ≈ 220.6 kPa ≈ 2.206 bar. Always check the sticker inside the driver's door for the exact recommended value, since it can be a gauge reading above atmospheric pressure rather than an absolute one.
What is the difference between mmHg and Torr, and how does this relate to a 120/80 blood pressure reading?
mmHg (millimeter of mercury) and Torr are nearly identical — 1 Torr is defined as 1/760 of a standard atmosphere (about 133.3224 Pa), while conventional mmHg is about 133.3224 Pa too, differing by less than 0.001%. A blood pressure reading of "120/80 mmHg" simply expresses two pressures in this unit: about 16.0 kPa (systolic) and 10.7 kPa (diastolic). This converter treats mmHg and Torr as equivalent for everyday use; it is a unit conversion tool only, not medical guidance.
Is my input sent to a server?
No. This pressure converter runs entirely in your browser — the number you type is never uploaded anywhere. The only thing saved is your last chosen unit pair (for example psi → bar), kept in your browser's local storage so it is ready next time. The value itself is not stored.