Pressure Converter
Convert pressure between pascals, bar, psi, atm and mmHg.
Results update as you type.
About this calculator
A pressure converter changes a pressure reading between pascals and kilopascals, bar and millibar, the standard atmosphere, psi, and the mmHg, torr and inHg units used in weather, medicine and vacuum work. All values convert through the pascal as a common base.
The reference points worth memorising are 1 atm = 101,325 Pa = 1.01325 bar ≈ 14.696 psi = 760 mmHg. A bar is very close to one atmosphere, and one psi is about 6,895 pascals, which is why tyre and industrial pressures move between bar and psi in a roughly 1-to-14.5 ratio.
Worked example: to convert 2 bar to psi, multiply by 14.5038, giving about 29.0 psi — a typical car tyre pressure. To convert a 120 mmHg blood-pressure reading to kilopascals, multiply by 0.133322, giving about 16.0 kPa. A results table shows the same pressure in every unit at once.
Frequently asked questions
How many psi are in a bar?
One bar equals about 14.5038 psi. A bar is close to one atmosphere, so car tyre pressures in bar and psi are roughly a 1-to-14.5 ratio.
What is one atmosphere?
One standard atmosphere (atm) is 101,325 pascals, about 1.013 bar or 14.696 psi. It is the average air pressure at sea level.
What is mmHg used for?
Millimeters of mercury measure blood pressure and barometric pressure. One mmHg is about 133.322 pascals, and 760 mmHg equals one atmosphere.
How do I convert psi to bar?
Divide psi by 14.5038, or multiply by 0.0689476. So 32 psi (a common tyre pressure) is about 2.2 bar. This pressure converter uses the exact factor of 6,894.76 pascals per psi.
What is the difference between torr and mmHg?
They are practically identical: one torr is defined as 1/760 of an atmosphere and one mmHg is about 133.322 pascals, differing only in the seventh significant figure. For everyday purposes they are interchangeable.
What is a millibar and where is it used?
A millibar is one-thousandth of a bar, or 100 pascals, and is the traditional unit for atmospheric pressure in weather reports. Standard sea-level pressure is about 1,013 mbar.
API — use this calculator from code
Call this calculator as a free JSON endpoint — no key required. Send the field values below as query parameters or JSON. Read the full API docs →
Endpoint
GET https://calculator.free/api/v1/pressure/curl
curl "https://calculator.free/api/v1/pressure/?amount=1&from=bar&to=psi"JavaScript fetch()
const r = await fetch(
"https://calculator.free/api/v1/pressure/?" + new URLSearchParams({
"amount": "1",
"from": "bar",
"to": "psi"
}));
const data = await r.json();
console.log(data.results);Results are estimates for general guidance only, not financial, medical or tax advice.