inHg Calculator
inHg Calculator: convert inhg instantly. Full formula, unit table, and worked example.
A pressure converter switches between pascals (Pa), kilopascals (kPa), megapascals (MPa), atmospheres (atm), bars (bar), pounds per square inch (psi), millimetres of mercury (mmHg / Torr), and inches of mercury (inHg). Pressure measurement spans from weather forecasting to tyre inflation, medical blood pressure readings, industrial hydraulics, scuba diving, and chemistry. Different fields use different units — knowing how to convert between them is essential for engineering, medicine, and scientific work.
- Enter the pressure value and select the source unit.
- The converter shows equivalents in all common units simultaneously.
- For tyres: use psi (US standard) or bar (European standard). For blood pressure: use mmHg. For weather: use hPa or mbar (equivalent). For scuba: use bar or atm.
Pressure conversion factors
1 atmosphere (atm) = 101,325 Pa = 14.696 psi = 1.01325 bar = 760 mmHg = 29.921 inHg
1 bar = 100,000 Pa = 14.5038 psi = 0.986923 atm = 750.062 mmHg
1 psi = 6,894.76 Pa = 0.068046 atm = 0.068948 bar = 51.715 mmHg
1 mmHg (Torr) = 133.322 Pa = 0.001316 atm = 0.001333 bar = 0.01934 psi
Pressure reference benchmarks
Common pressure values
Standard atmospheric pressure at sea level: 1 atm = 101.325 kPa = 14.696 psi = 1013.25 mbar. Normal blood pressure: systolic 120 mmHg / diastolic 80 mmHg (written 120/80). Car tyre pressure: 30–35 psi (2.07–2.41 bar). SCUBA tank: 200–300 bar (2,900–4,350 psi). Hydraulic systems: 100–700 bar. Deep sea at Mariana Trench (11 km): ~1,100 atm = ~16,000 psi. Pressure cooker: 1.5–2.0 atm above atmospheric.
Conversion tips and best practices
- Weather forecasts use hPa (hectopascals) — 1 hPa = 1 mbar = 100 Pa; standard sea-level pressure = 1013.25 hPa.
- Gauge pressure = absolute pressure − atmospheric pressure. Tyre gauges read gauge pressure — a tyre showing 35 psi gauge is at 49.7 psi absolute.
- Blood pressure mmHg is a medical convention — 1 mmHg = 133.3 Pa; the "120/80 mmHg" standard is used worldwide regardless of local pressure units.
- Deep water: pressure increases by approximately 1 atm (14.7 psi) for every 10 metres (33 feet) of water depth.
- Under-inflated car tyres lose approximately 0.1–0.2% fuel efficiency per 1 psi below optimal pressure — keeping tyres at the correct pressure (typically 30–35 psi) saves fuel and extends tyre life.
- The lowest atmospheric pressure ever recorded was 870 hPa (25.69 inHg) in Typhoon Tip (1979) — nearly 14% below standard sea-level pressure.
- Humans can withstand approximately 3–4 atm of absolute pressure (about 20–30 m water depth) without a pressure suit — beyond this, decompression sickness risk increases significantly.
Common mistakes to avoid
- Confusing gauge and absolute pressure — a tyre pressure of 0 psi gauge means flat, not a vacuum; it is at atmospheric pressure (14.7 psi absolute).
- Using the wrong mmHg standard — blood pressure mmHg uses mercury density at a specific temperature; "torr" and "mmHg" are nearly identical but technically different above 0°C.
- Treating millibar (mbar) and Pascal (Pa) as the same — 1 mbar = 100 Pa; they are not equal.
Pressure vessel design, gas cylinder ratings, hydraulic system specifications, and medical device pressure settings must comply with applicable ASME, ISO, OSHA, FDA, and local regulatory standards. Always use calibrated equipment for safety-critical pressure measurement.