All Common Units
Covers Pascal, kPa, MPa, bar, millibar, psi, atm, mmHg, torr, and inHg in one interface. No hunting between separate tools for medical, engineering, meteorological, and automotive pressure values.
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Pressure Converter
Translate pascals, kilopascals, bar, PSI, atmospheres, and torr with SI-aligned constants.
About Pressure Converter
Pressure values appear across radically different scales and unit systems depending on the field — a tire shop uses psi, a weather station uses hectopascals, a chemistry lab uses atmospheres, and a medical device uses millimetres of mercury. This pressure converter covers every common unit: Pascal (Pa), kilopascal (kPa), megapascal (MPa), bar, millibar, psi, atmosphere (atm), mmHg, torr, and inch of mercury (inHg). All fields update simultaneously when you type, using NIST-exact conversion constants. Quick-reference presets for standard atmospheric pressure, typical tire inflation, and common vacuum readings let you sanity-check conversions against known values. Six decimal places of output precision makes the tool equally suitable for engineering datasheets and everyday tire-inflation checks. Everything runs locally in your browser.
Why use Pressure Converter
Live Multi-unit
Type a value in any field and every other unit updates immediately — no submit button, no page reload. Changing from psi to bar to kPa is instant, making iterative calculations frictionless.
SI-correct Factors
Uses NIST-published exact conversion constants rather than rounded approximations. The relationship between Pascal, bar, and atm is defined by international standards — the tool reflects those exact values.
Reference Pressures
Built-in presets for common real-world pressures — standard atmosphere (101,325 Pa), typical car tire inflation (220 kPa / 32 psi), blood pressure systolic (120 mmHg) — let you ground-truth your conversion instantly.
Decimal Precision
Outputs up to six decimal places, providing enough resolution for engineering datasheets, scientific lab reports, and pneumatic system specifications where three-significant-figure rounding causes downstream errors.
Offline Capable
All conversion factors are computed in pure browser JavaScript. No API call is needed, so the tool works on a factory floor, in a workshop, or anywhere connectivity is unreliable.
How to use Pressure Converter
- Click into the unit field you want to convert from and type your value.
- Read all other unit fields update instantly with NIST-exact converted values.
- Adjust the decimal precision if you need more significant figures for engineering work.
- Click a quick-reference preset (standard atm, tire pressure, ocean depth) to load a known value.
- Use gauge-to-absolute notes to add or subtract one atmosphere when your spec requires it.
- Copy any field value with its unit suffix using the copy icon beside it.
When to use Pressure Converter
- Checking tire pressure when a car's manual lists psi but your gauge reads kPa or bar.
- Converting a hydraulic or pneumatic system spec from bar to psi for a US-manufactured part.
- Reading a weather barometer in hPa and comparing it to the standard atmosphere value.
- Translating blood pressure values in mmHg to Pascal for a physics or biology assignment.
- Verifying an autoclave sterilisation spec that mixes bar and psi in different sections of a manual.
- Comparing vacuum pump specs where one datasheet uses torr and another uses Pa.
Examples
Tire pressure
Input: 32 psi
Output: 220.6 kPa = 2.206 bar = 1,655 mmHg
Atmospheric
Input: 1 atm
Output: 101,325 Pa = 1.01325 bar = 14.6959 psi = 760 mmHg
Vacuum gauge
Input: 100 mmHg
Output: 13,332 Pa = 13.332 kPa = 1.934 psi
Tips
- 1 atm ≈ 1.01325 bar ≈ 14.7 psi — close enough for estimates, but not the same; never use them interchangeably in precision specs.
- Tire shops post psi in the US and kPa in metric countries; your car's door sticker has both values and is the authoritative source.
- mmHg and torr are effectively identical for every practical application — the difference is sub-ppm.
- Gauge pressure = absolute pressure minus 1 atm — always clarify which type a specification is using before converting.
- Engineering specs typically express pressure in Pa, kPa, MPa, or bar — never mix units within a single document without converting explicitly.
Frequently Asked Questions
What is 1 atmosphere in psi?▾
Exactly 1 atm = 101,325 Pa = 14.6959 psi. In everyday use this is rounded to 14.7 psi, but for precision engineering specifications always use the full value.
Are bar and atm the same?▾
They are close but not equal. 1 bar = 100,000 Pa exactly; 1 atm = 101,325 Pa. The difference is about 1.3%, which matters in precision work but is negligible for most industrial estimates.
What is the difference between absolute and gauge pressure?▾
Absolute pressure is measured relative to a perfect vacuum. Gauge pressure is measured relative to local atmospheric pressure. Gauge pressure = absolute pressure − atmospheric pressure (~101.325 kPa). Many tire gauges and industrial instruments read gauge pressure.
Why is psi used in the US instead of kPa?▾
Psi is part of the US customary system that historically standardised around pounds and inches. Most other countries adopted the SI metric system and use kPa or bar for pressure. Both units are exact — neither is an approximation.
How do mmHg and torr differ?▾
They are nearly identical: 1 torr = 1 mmHg to within 1 part in 7 million. The torr was historically defined by the barometric reading in millimetres of mercury but later given an exact Pa-based definition. In practice they are interchangeable.
What's standard tire pressure in psi vs kPa?▾
Most passenger car tires are inflated to 30–35 psi, which equals roughly 207–241 kPa or 2.07–2.41 bar. Always check your specific vehicle's door-jamb sticker rather than the tire sidewall for the recommended value.
How does altitude affect atmospheric pressure?▾
Atmospheric pressure decreases with altitude at roughly 12 Pa per metre at sea level. At 1,000 m (3,280 ft), pressure is about 89,875 Pa vs 101,325 Pa at sea level — an 11% reduction that affects both weather instruments and oxygen availability.
What unit does aviation use?▾
Aviation altimetry uses hectopascals (hPa) in most of the world and inches of mercury (inHg) in the US, Canada, and Japan. 1013.25 hPa = 29.92 inHg = standard sea-level pressure, the QNH reference point for altimeter settings.
Explore the category
Glossary
- Pascal (Pa)
- The SI derived unit of pressure, defined as one Newton per square metre. Most scientific and engineering standards express pressure in Pascals or multiples thereof (kPa, MPa). Standard sea-level atmospheric pressure is 101,325 Pa.
- Bar
- A non-SI metric unit of pressure equal to exactly 100,000 Pa. Widely used in European industry, meteorology (millibar = hPa), and hydraulics. 1 bar is approximately equal to one standard atmosphere.
- Pound per Square Inch (psi)
- A US customary unit of pressure equal to one pound-force applied to an area of one square inch. Commonly used for tire inflation, hydraulic systems, and HVAC equipment in the United States.
- Atmosphere (atm)
- A unit of pressure defined as exactly 101,325 Pa, representing the average sea-level atmospheric pressure. Used as a reference standard in chemistry and physics, and as a rough rule-of-thumb in diving depth calculations.
- Millimetre of Mercury (mmHg)
- A pressure unit defined as the pressure exerted by a 1 mm column of mercury at 0 °C under standard gravity. Widely used in medicine for blood pressure readings and in meteorology for barometric pressure.
- Torr
- A unit of pressure equal to 1/760 of a standard atmosphere (approximately 133.322 Pa), nearly identical to 1 mmHg. Commonly used in vacuum engineering and low-pressure physics experiments.