Pressure Converter
Convert pressure between psi, bar, kilopascals, atmospheres, mmHg, and inHg — the units used in tyres, weather, diving, and engineering.
Cómo usar esta calculadora
- 1Enter the pressure value.
- 2Choose the unit it's currently in.
- 3Read the equivalent in psi, bar, kPa, atmospheres, and mercury columns.
- 4Use the pascal-based conversions for any engineering or science context.
Cómo funciona
Pressure conversion
1 atm = 101,325 Pa = 1.01325 bar = 14.696 psi = 760 mmHg 1 bar = 100,000 Pa, 1 kPa = 1,000 Pa 1 psi = 6,894.76 Pa, 1 mmHg = 133.322 Pa convert via pascals: value × factorₐ ÷ factor_b
Pressure is force distributed over an area, and it is measured in a bewildering variety of units because different fields adopted their own. Scientists and engineers use the pascal, the SI unit, equal to one newton spread over one square metre; because a pascal is tiny, the kilopascal and the bar (100,000 pascals, close to atmospheric pressure) are common. Tyre pressures and many American engineering contexts use pounds per square inch. Meteorologists report weather in millibars or hectopascals, and older instruments measure in millimetres or inches of a mercury column, a legacy of the barometer. The clean way to convert between any of them is to route through a single base unit: multiply the input by its factor to pascals, then divide by the target unit's factor. This calculator does exactly that, giving every common unit at once.
Ejemplo resuelto
One atmosphere of pressure equals 101,325 pascals, which is 1.01325 bar, 14.696 psi, or 760 mmHg. So a car tyre inflated to 32 psi is at about 2.2 bar or 221 kPa, and a scuba diver at 10 metres' depth experiences roughly 2 atm — double the surface pressure.
Pressure Converter: la guía completa
Why pressure has so many units
Few quantities are measured in as many different units as pressure, and the reason is history: different fields developed independently and each settled on what was convenient. Meteorology grew up with the mercury barometer, so atmospheric pressure was naturally expressed as the height of a mercury column — millimetres or inches of mercury — and later as millibars. Tyre and industrial pressures in the English-speaking world adopted pounds per square inch, an intuitive force-over-area unit. Science standardised on the pascal, and much of European industry on the bar, which is conveniently close to atmospheric pressure.
The result is that the same physical pressure can be quoted half a dozen ways, and moving between them is a constant practical need. A weather report in hectopascals, a tyre gauge in psi, a pressure cooker rated in bar, a blood-pressure reading in mmHg, and a vacuum specified in pascals all describe the same underlying quantity. Converting reliably matters whenever these worlds meet — which they do more often than people expect, from inflating tyres to interpreting a scientific instrument.
Atmospheric pressure and the mercury units
Standard atmospheric pressure at sea level — the weight of the air column above us — is the natural reference point for pressure, and it ties several units together. It equals 101,325 pascals, 1.01325 bar, 14.696 psi, and famously 760 millimetres of mercury. That last figure is not arbitrary: it is literally how high the atmosphere can push a column of mercury up an evacuated tube, which is how the barometer works and why mercury units persist in weather and medicine.
This reference also explains the important distinction between absolute and gauge pressure. Absolute pressure is measured from a perfect vacuum, while gauge pressure is measured relative to the surrounding atmosphere. A tyre gauge reading 32 psi shows gauge pressure — the tyre is 32 psi above atmospheric, so its absolute pressure is about 47 psi. Most everyday pressure measurements, from tyres to blood pressure, are gauge pressures, which is why they read zero when open to the air even though the atmosphere is pressing on everything. Keeping the two straight avoids a factor-of-one-atmosphere error.
Pressure in everyday life
Pressure conversions come up in a surprising number of ordinary situations. Inflating a tyre from a gauge marked in psi when the car manual specifies bar, reading a weather forecast that gives pressure in hectopascals, following a recipe for a pressure cooker rated in a foreign unit, or checking a blood-pressure reading in mmHg all require moving between units. Getting the conversion right matters: under- or over-inflating a tyre affects safety and fuel economy, and misreading a pressure specification in an engineering context can be dangerous.
The units also carry intuition once you are fluent in them. Knowing that atmospheric pressure is about 14.7 psi or 1 bar helps you judge whether a reading is reasonable. Understanding that pressure roughly doubles for every 10 metres of water depth explains why divers must ascend slowly and why deep-sea equipment is built so robustly. Recognising that weather systems differ by only tens of hectopascals around the roughly 1013 hPa average makes a forecast map readable. Converting between units is the mechanical part; the payoff is being able to reason about pressure across all the contexts where it shows up.
Preguntas frecuentes
How do I convert psi to bar?
Multiply psi by 0.0689 to get bar, or divide by 14.5. So 32 psi is about 2.2 bar. Both are units of pressure; 1 bar equals 100,000 pascals and is close to atmospheric pressure, while 1 psi equals about 6,895 pascals.
What is standard atmospheric pressure?
At sea level it's 1 atmosphere, equal to 101,325 pascals, 1.01325 bar, 14.696 psi, or 760 mmHg. It's the weight of the air column above you and the reference point for weather pressure and for 'gauge' pressures like tyre readings, which are measured relative to it.
What's the difference between gauge and absolute pressure?
Absolute pressure is measured from a perfect vacuum; gauge pressure is measured relative to the surrounding atmosphere. A tyre gauge reading 32 psi is 32 psi above atmospheric, so about 47 psi absolute. Most everyday measurements, like tyre and blood pressure, are gauge pressures.
Why is pressure measured in millimetres of mercury?
It's a legacy of the mercury barometer, where atmospheric pressure pushes mercury up an evacuated tube — 760 mm at sea level. The unit persists in weather and medicine (blood pressure) because those fields grew up with mercury instruments. It equals about 133 pascals per millimetre.