Pressure Unit Converter — psi, Bar, atm, Pascal and More

Pressure units are one of those areas where different industries picked different standards and nobody agreed on a universal one. Tire pressure in the US is measured in psi. Meteorologists use hectopascals or millibars. Physicists use pascals. Diving depth is sometimes described in atm or bar. A scuba diver, a mechanic, and a meteorologist looking at the same atmospheric measurement would all write it down differently.

The CalcHub pressure converter gives you all of them at once.

Pressure Unit Conversion Table

From	To	Multiply by
1 psi	bar	0.0689476
1 psi	pascal (Pa)	6894.76
1 psi	atm	0.068046
1 bar	psi	14.5038
1 bar	pascal (Pa)	100,000
1 bar	atm	0.986923
1 atm	psi	14.6959
1 atm	bar	1.01325
1 atm	pascal (Pa)	101,325
1 atm	mmHg (torr)	760
1 kPa	psi	0.145038
1 MPa	psi	145.038

Real-World Pressure Reference Points

Situation	Pressure
Standard atmosphere (sea level)	1 atm = 101,325 Pa = 14.696 psi = 1.01325 bar
Car tire (typical)	30–35 psi = 2.07–2.41 bar
Bicycle tire (road)	80–130 psi = 5.5–9.0 bar
Blood pressure (systolic normal)	120 mmHg = 16 kPa
Scuba tank (full)	~200 bar = 2,900 psi
Household water pressure	40–80 psi = 2.76–5.52 bar
Top of Mount Everest	~0.337 atm = 33.7 kPa

Where Pressure Conversions Come Up

Tire inflation is the most common use case for everyday people. European tire specs and many car manuals list pressure in bar, while American vehicles use psi. If your car manual says inflate to 2.4 bar and your gauge reads psi, that's 34.8 psi — round to 35. Medical blood pressure is measured in mmHg (millimeters of mercury), a unit that has been used since mercury sphygmomanometers were invented. "120 over 80" means 120 mmHg systolic pressure, 80 mmHg diastolic. Weather forecasting uses hectopascals (hPa) or millibars (mbar) — they're numerically identical (1 hPa = 1 mbar = 100 Pa). Standard sea-level pressure is 1013.25 hPa. A reading below 1000 hPa typically indicates low pressure (rain likely); above 1025 hPa means high pressure (clear weather). Industrial and engineering applications use MPa (megapascals) or psi for hydraulic systems, pipe pressures, and material strength specs.

How to Use the CalcHub Pressure Converter

1. Visit calchub.in and open the Pressure Converter
2. Enter your pressure value
3. Select the source unit (psi, bar, atm, Pa, kPa, MPa, mmHg, etc.)
4. The converter shows equivalents across all units immediately

This is especially useful when you have a specification in one unit and measuring equipment calibrated in another.

Common Mistakes

Forgetting gauge pressure vs. absolute pressure. Tire pressure is gauge pressure — it reads zero at atmospheric pressure, so a "35 psi" tire actually has 35 + 14.7 = 49.7 psi absolute pressure. Scientific calculations usually require absolute pressure. Most converters (including CalcHub) work with absolute values unless specified. Confusing kPa and MPa. Kilopascals and megapascals are both common in specifications. 1 MPa = 1,000 kPa. A pressure rating of 10 MPa is very different from 10 kPa.

What is the difference between bar and atm?

Almost nothing, practically speaking. 1 bar = 100,000 Pa. 1 atm = 101,325 Pa. Bar was defined as a round number close to atmospheric pressure for engineering convenience. Most industrial pressure gauges use bar for this reason.

Why is blood pressure measured in mmHg?

The mercury column manometer was the standard tool for measuring blood pressure for over a century. Even though digital monitors no longer use mercury, the unit stuck. 1 mmHg = 133.322 Pa, and it's formally equivalent to 1 torr.

What pressure is dangerous for scuba diving?

At depth, ambient pressure increases by 1 atm for every 10 meters of seawater. At 30 meters depth, you're under 4 atm total (3 atm water + 1 atm atmospheric). Dive tanks are pressurized to ~200–300 bar to store enough gas for a reasonable dive duration.

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