Pressure

Multiply by 0.0689476: psi × 0.0689476 = bar. Example: 35 psi = 2.413 bar. Reverse (bar to psi): multiply by 14.5038. Example: 2.5 bar = 36.26 psi. The factor comes from the exact definition: 1 psi = 1 lbf/in² = 6,894.76 Pa, and 1 bar = 100,000 Pa, so 1 psi = 6894.76 / 100000 bar = 0.068948 bar.

1 bar = 14.5038 psi and 1 bar = 100 kPa exactly. The bar was defined as exactly 100,000 Pa, making the bar-to-kPa conversion trivially simple (no calculation needed — just shift the decimal). Bar to psi: 1 bar = 14.504 psi; 2 bar = 29.008 psi; 2.5 bar = 36.26 psi; 3 bar = 43.51 psi. Tyre specifications often appear in all three — 2.4 bar = 240 kPa = 34.8 psi.

Multiply by 0.145038: kPa × 0.145038 = psi. Example: 220 kPa = 31.9 psi; 240 kPa = 34.8 psi; 250 kPa = 36.3 psi. Common vehicle door placards in Australia, Europe, and Japan show kPa; US vehicles show psi. The recommended inflation figures are identical pressures — just different units. At 200 kPa (29 psi), most passenger cars are noticeably under-inflated.

mmHg to kPa: mmHg × 0.133322 = kPa. Example: 120 mmHg = 16.0 kPa; 80 mmHg = 10.67 kPa. To Pa: mmHg × 133.322 = Pa. The unit mmHg (millimetre of mercury) is defined as the pressure exerted by a 1 mm column of mercury under standard gravity, which equals 133.322 Pa exactly. Blood pressure is reported in mmHg worldwide because the mercury sphygmomanometer was the first reliable measurement instrument — and clinical training is anchored to those reference values.

Torr to Pa: Torr × 133.322 = Pa. Torr to atm: Torr ÷ 760 = atm (since 1 atm = 760 Torr exactly). 1 Torr = 1 mmHg to six significant figures — they are treated as identical in most laboratory and clinical contexts. Example: 500 Torr = 500 mmHg = 66,661 Pa = 0.6579 atm. Torr appears in vacuum pump ratings, gas chromatography, and mass spectrometry — contexts where sub-atmospheric pressures matter and mmHg and Torr are used interchangeably.

Yes — decimal inputs are fully supported. Examples: 2.5 bar → 36.26 psi → 250 kPa; 35.5 psi → 2.448 bar → 244.8 kPa; 101.325 kPa → 1 atm → 760 mmHg. The tool uses 64-bit floating-point precision throughout, so results like 1 atm = 760.000 Torr are reproduced exactly. Precision matters in lab settings, compressed-gas work, and calibration tasks where rounding introduces cumulative error.

Absolute pressure is measured from perfect vacuum (0 Pa). Gauge pressure is measured relative to the local atmosphere — so a tyre gauge reading of 35 psi means 35 psi above atmospheric pressure, or about 49.7 psia absolute. The suffix "g" means gauge (psig, barg) and "a" means absolute (psia, bara). Gas law calculations (PV = nRT) always require absolute pressure — using gauge readings here gives incorrect results. Blood pressure, tyre pressure, and most industrial instruments report gauge pressure.

Mercury manometers were the first instruments reliable enough for clinical blood pressure measurement, introduced by Riva-Rocci in 1896. The medical profession built its training, diagnostic criteria, drug dosing thresholds (e.g., "treat if systolic > 140 mmHg"), and device design around this unit over more than a century. Despite mmHg being a non-SI unit, the WHO and medical societies worldwide retain mmHg to preserve continuity with decades of clinical research. SI-equivalent values (120 mmHg ≈ 16 kPa) are technically accurate but clinically unfamiliar — introducing kPa in clinical practice would create dangerous ambiguity in drug and alarm thresholds.

Oil and gas uses psi almost universally in the US and internationally for wellhead, pipeline, and reservoir pressures — primarily because US companies dominated early petroleum engineering. Pressures range from a few hundred psi (pipeline distribution) to 10,000–20,000 psi in deepwater wellheads and high-pressure hydraulic fracturing. MPa and bar appear in international standards and European equipment specs. Specific terms: SITP (shut-in tubing pressure), BHP (bottomhole pressure), and MAOP (maximum allowable operating pressure) are all reported in psi in most field documentation.