Pressure Converter

Every pressure unit covered

This converter supports pascals, hectopascals, kilopascals and megapascals, plus bar, millibar, atmospheres, torr (mmHg), psi and inches of mercury. That range covers weather, tire pressure, hydraulics, vacuum systems and lab work.

Conversions are based on standard definitions (1 atm = 101,325 Pa, 1 psi = 6894.757 Pa), so results are precise to scientific standards.

Common pressure conversions

• psi to bar and bar to psi for tires
• kPa to psi for engineering
• mmHg to kPa for blood pressure and vacuum

Key features at a glance

• SI units: pascals, hectopascals, kilopascals, megapascals
• Other units: bar, millibar, atmospheres, torr (mmHg), psi, inHg
• Live conversion table updates as you type
• Exact results based on standard definitions
• Covers weather, tires, hydraulics, vacuum, and lab work
• Runs entirely in your browser, even offline

What pressure is and how it is measured

Pressure is force spread over an area — the same push concentrated on a small area produces more pressure than spread over a large one. The SI unit, the pascal, is one newton per square meter, which is a very small amount, so real-world pressures use larger units: kilopascals for engineering, hectopascals for weather, and megapascals for high-pressure systems. Many fields also keep traditional units like psi (pounds per square inch) and bar.

Because all these units measure the same physical quantity, converting between them is exact once the definitions are fixed. One atmosphere is defined as exactly 101,325 pascals, and one psi as about 6,894.76 pascals. The converter applies these precise relationships, so a tire pressure in psi, a weather reading in hectopascals, and a lab vacuum in torr all translate cleanly into one another.

Absolute versus gauge pressure

There is a crucial distinction the raw numbers do not show: whether a pressure is absolute or gauge. Absolute pressure is measured against a perfect vacuum, while gauge pressure is measured relative to the surrounding atmosphere. A tire gauge reads gauge pressure, so a tire at '32 psi' is actually at about 32 psi above atmospheric, or roughly 47 psi absolute.

This matters because using the wrong reference can cause significant errors in engineering and science. Weather pressures are absolute, tire and many industrial pressures are gauge, and vacuum measurements are often expressed as how far below atmospheric they sit. The converter handles the unit math, but it is up to you to know which reference your figure uses — a detail that trips up even experienced practitioners.

Pressure units across different fields

Each application has its preferred unit for historical and practical reasons. Meteorologists use hectopascals (numerically identical to the older millibar), so a typical sea-level pressure reads around 1013 hPa. Drivers and mechanics use psi or bar for tires, medical professionals use millimeters of mercury (mmHg) for blood pressure, and aviation uses inches of mercury for altimeter settings.

Scientists and engineers working with vacuums use torr or pascals, and hydraulic systems use bar or megapascals. This patchwork means a single pressure value often needs translating into the unit a particular audience expects. By covering every common unit in one place, the converter lets you move a reading from one field's convention to another's without hunting for the right factor.

Tips for converting pressure

• Standard atmospheric pressure is 101,325 Pa, 1013.25 hPa, or 14.7 psi
• 1 bar is very close to one atmosphere (about 0.987 atm)
• Tire gauges read gauge pressure — pressure above atmospheric
• Weather uses hectopascals; millibar is the same value
• Blood pressure uses mmHg (torr); 1 mmHg is about 133.3 Pa

Why choose our pressure converter?

Our converter is completely free with no signup, no limits, and no subscription. It runs entirely in your browser, so conversions are instant, it works offline, and the values you enter never leave your device.

It is one of more than 200 free tools on ToopTools, and you can pin it to your My Workspace, a personalized workspace where you keep the tools you use most in a single dashboard. Beside the other unit converters, it covers every pressure conversion from tires to vacuums in one place.

Common use cases

Drivers and mechanics use the pressure converter to switch tire pressures between psi and bar, weather enthusiasts read barometric pressure in hectopascals or inches of mercury, and divers and engineers work in atmospheres and bar. It puts every pressure unit on the same footing.

Scientists and lab technicians convert vacuum readings in torr and pascals, medical contexts use mmHg for blood pressure, and HVAC and hydraulics professionals use bar and megapascals. Because every unit appears at once, a single reading instantly reads across all the conventions different fields use.

Is the pressure converter free?

Yes. It is completely free with no account, no sign-up, and no usage limits. Convert as many pressures as you like at no cost.

How do I convert psi to bar?

Multiply psi by about 0.0689 to get bar, or enter the value in the converter. One bar is about 14.5 psi, so a 32 psi tire is roughly 2.2 bar.

What is standard atmospheric pressure?

Standard atmospheric pressure at sea level is 101,325 pascals, equal to 1013.25 hectopascals, 1 atmosphere, or about 14.7 psi. Weather and altitude measurements are referenced to this value.

What is the difference between absolute and gauge pressure?

Absolute pressure is measured against a vacuum, while gauge pressure is measured relative to atmospheric pressure. A tire gauge reads gauge pressure, so the absolute pressure is about one atmosphere higher.

What unit is used for blood pressure?

Blood pressure is measured in millimeters of mercury (mmHg), the same unit as torr. One mmHg is about 133.3 pascals, and a typical reading is around 120/80 mmHg.

Are my conversions kept private?

Yes. Everything is computed in your browser and nothing is uploaded, so the values you enter stay private and the tool works without an internet connection.

How do I convert bar to psi?

Enter the pressure in bar and choose psi as the target, and the converter shows the result instantly. It also covers pascals, kilopascals, atmospheres, and millimeters of mercury, so you can switch between scientific and everyday pressure units in one step.

Does the pressure converter work offline?

Yes. The conversion runs entirely in your browser, so once the page has loaded the tool works without an internet connection, and nothing you enter is uploaded — it stays private on your own device.