Pressure Converter

Converts pressure across pascals, hectopascals, bar, atmospheres, psi and mmHg. One atmosphere is 101,325 Pa — equivalently 1.013 bar, 14.7 psi, or 760 mmHg — and every field updates from whichever you type in.

How to use

1. Enter the pressure in the unit you have.
2. Read the equivalents in the others.
3. Note whether your source is absolute or gauge pressure — tyre figures are gauge (above atmospheric).
4. Weather values are hPa; medical blood pressure is mmHg; tyres are psi or bar.

When you actually need this

• Setting tyre pressure when the manual says bar and the gauge says psi — 32 psi is 2.2 bar.
• Reading weather-map hectopascals against the 1,013 hPa standard.
• Interpreting equipment specs mixing bar, psi and kPa.
• Converting scuba or industrial pressures between atm and bar.

One physical thing, many habits

The pascal is the SI unit but inconveniently small — atmospheric pressure is about 101,325 of them — so each field kept its own habit: meteorology uses hPa (which made the old millibar numbers carry over unchanged), medicine stayed with mmHg from mercury-column instruments, tyres speak psi in imperial markets and bar in metric ones. Bar and atmosphere differ by 1.3% — close enough to confuse, far enough to matter in precise work. Gauge versus absolute is the practical trap: a tyre gauge reads pressure above atmospheric, so 32 psi gauge is roughly 46.7 psi absolute. Compare like with like.

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FAQ

How precise are the conversion factors in Pressure Converter?

The factors are the internationally defined exact values — one inch is exactly 25.4 millimetres, one pound is exactly 0.45359237 kilograms, and so on. Results are computed at full floating-point precision and only rounded for display.

Can I convert between metric and imperial units in both directions?

Yes. Enter a value in any field and every other unit updates at once, so the conversion works in either direction without switching modes or pressing a button.

Why does the last decimal place sometimes look off?

Because many conversions are irrational in decimal form and browsers use binary floating point, the final digit can differ by a tiny amount. The displayed value is rounded sensibly for everyday use; for laboratory or engineering work, carry the unrounded figure through your own calculation.