PSI to Bar Converter

Pressure is one of the most frequently converted quantities in everyday life, because the world uses two measurement systems side-by-side. The United States, Canada (partially), and a few other countries still publish tire pressures, gas-line pressures, hydraulic-system ratings, and scuba-tank specifications in pounds per square inch (psi). Most of the rest of the world, Europe, Asia, South America, scientific and engineering literature everywhere, uses bar, kilopascals (kPa), or standard atmospheres (atm). The numbers are not interchangeable: 1 bar is not 1 psi, and confusing them on a tire gauge, a regulator, or a pressure vessel can range from a mild nuisance (a softer-than-intended ride) to a serious safety problem (over-pressurised scuba tank, mis-rated hydraulic line).

The PSI to Bar converter on this page is a fast, accurate, browser-based tool that switches between six of the most common pressure units, psi, bar, kPa, atm, MPa, and mmHg, with live cross-update as you type. Type a value into any field and the other five recalculate instantly. There is a swap button for the most common conversion pair (psi and bar), a copy-to-clipboard button on every field, and a built-in reference table covering typical car tires, bicycle tires, scuba tanks, hydraulic presses, residential natural gas, and standard atmospheric pressure. Everything runs locally in your browser; nothing is uploaded.

How to Use the PSI to Bar Converter

1. Click any input field, psi, bar, kPa, atm, MPa, or mmHg, and type the pressure value you want to convert. The fields accept whole numbers, decimals, and negative values (for vacuum readings).
2. All other fields update live as you type. The currently edited field is highlighted with an accent-coloured border and labelled "typing…"; the others are labelled "live" and show the converted value rounded to four decimal places.
3. Use the ⇄ Swap psi ↔ bar button above the fields to swap the active focus between psi and bar. This is the most common conversion pair, especially when comparing a US gauge with a European specification sheet.
4. Click Copy below any field to put its exact numeric value on your clipboard. The button briefly turns green and shows "Copied!" so you know the write succeeded.
5. Refer to the Common pressure reference points table at the bottom for typical real-world values: standard atmosphere, car tire, road-bike tire, full scuba tank, residential natural gas, and a typical hydraulic press.

The calculator does not perform any network calls. Your input value, your results, and your clipboard activity all stay on your device, which makes it safe to use on air-gapped workshop laptops and on shared terminals in a lab.

The Formulas

Every conversion on this page is built on a single SI base unit, the pascal (Pa), defined as one newton per square metre. One kilopascal equals exactly 1 000 pascals. The other units are defined against this base:

• 1 psi = 6 894.757293168 Pa = 6.894757293168 kPa (exact; 1 psi is the pressure produced by one pound-force applied to one square inch, with 1 inch = 0.0254 m exactly).
• 1 bar = 100 000 Pa = 100 kPa (exact; bar is a metric unit of pressure widely used in engineering and meteorology; the bar is not an SI unit but is accepted for use with the SI).
• 1 atm = 101 325 Pa = 101.325 kPa (exact; this is the standard atmosphere as defined by the International Union of Pure and Applied Chemistry, IUPAC, and used as a reference in chemistry, physics, and engineering).
• 1 MPa = 1 000 000 Pa = 1 000 kPa (megapascal; common in materials science and high-pressure hydraulics).
• 1 mmHg ≈ 133.322387415 Pa = 0.133322387415 kPa (millimetre of mercury; legacy medical and vacuum-science unit, equal to the pressure of a 1 mm column of mercury under standard gravity).

The six useful closed-form factors you will see most often:

• 1 psi = 0.0689476 bar (rounded; exact value 0.0689475729…)
• 1 bar = 14.5037738 psi (exact in the US customary foot-pound-second system)
• 1 psi = 6.8947573 kPa (exact)
• 1 atm = 14.6959488 psi (exact; derived from 101 325 Pa ÷ 6 894.757293168 Pa/psi)
• 1 bar = 100 kPa (definition, exact)
• 1 atm = 1.01325 bar (derived from 101.325 kPa ÷ 100 kPa/bar)

To convert any value, multiply by the source unit's factor in kPa, then divide by the target unit's factor in kPa. The calculator does this automatically, but the two-step method is the cleanest way to remember why the numbers look the way they do.

Worked Examples

Example 1, 32 psi (a typical car tire pressure).

1. Convert psi to kPa: 32 × 6.8947573 = 220.6322 kPa.
2. Convert kPa to bar: 220.6322 ÷ 100 = 2.2063 bar.
3. Convert bar to atm: 2.2063 ÷ 1.01325 ≈ 2.1774 atm.

A tire inflated to 32 psi is therefore at about 2.21 bar or 220.6 kPa. European tire-pressure placards typically list 2.2 bar, which is the same physical state.

Example 2, 1 atm (standard atmospheric pressure at sea level).

1. 1 atm = 101.325 kPa (definition).
2. Convert kPa to bar: 101.325 ÷ 100 = 1.01325 bar.
3. Convert kPa to psi: 101.325 ÷ 6.8947573 ≈ 14.6959488 psi.

Atmospheric pressure is therefore about 14.70 psi or 1.013 bar. This is the reference for "zero" on a barometric altimeter and for "zero gauge pressure" on most workshop gauges, a gauge reads the difference between the absolute pressure inside the system and the local atmospheric pressure.

Example 3, 100 psi (a moderately high pressure used in some industrial cleaning, paint spraying, and pneumatic tools).

1. 100 × 6.8947573 = 689.47573 kPa.
2. 689.47573 ÷ 100 = 6.89476 bar.
3. 689.47573 ÷ 101.325 ≈ 6.8046 atm.

So 100 psi ≈ 6.89 bar ≈ 689.5 kPa. Compare this to a road-bike tire (80 psi ≈ 5.52 bar) and a typical hydraulic press (1 500 psi ≈ 103.4 bar) to anchor the feel of these numbers.

Example 4, 1 bar (a round number frequently seen on European tire labels and in European paint specifications).

1. 1 bar × 100 = 100 kPa.
2. 100 kPa ÷ 6.8947573 ≈ 14.5037738 psi.
3. 100 kPa ÷ 101.325 ≈ 0.986923 atm.

1 bar is therefore about 14.50 psi or 0.987 atm. It is intentionally close to, but slightly less than, one standard atmosphere.

Where PSI and Bar Show Up in Everyday Life

The psi/bar duality shows up in more places than most people realise.

Tires. US passenger-car door-stickers list pressures in psi (commonly 30 to 35 psi cold). European placards list the same physical state in bar (commonly 2.0 to 2.4 bar). Road-bike tires run much higher (80 to 130 psi ≈ 5.5 to 9.0 bar); mountain-bike tires much lower (25 to 40 psi ≈ 1.7 to 2.8 bar).

Hydraulics. Workshop hydraulic presses, automotive brake systems, and construction machinery are typically rated in either psi or bar depending on the country of manufacture. A 1 500 psi hydraulic press is roughly 103 bar; an automotive brake system operating around 800 to 1 200 psi is roughly 55 to 83 bar.

Scuba and paintball. A standard aluminium scuba tank is filled to about 3 000 psi (≈ 207 bar). Some European brands label the same tank at 200 bar or 232 bar. Paintball CO₂ cylinders are typically 1 800 to 2 600 psi (124 to 179 bar).

Residential natural gas. US appliances run on about 0.25 psi "pounds at the regulator" (about 7 inches water column, or roughly 17 mbar). European appliances run on about 20 to 25 mbar natural gas or 30 to 50 mbar LPG. Both feel tiny compared to industrial pressures but are very different physical states.

Atmospheric science and weather. Meteorologists use hectopascals (hPa) on weather maps; 1 hPa = 100 Pa = 0.1 kPa, so a sea-level pressure of 1 013.25 hPa equals 101.325 kPa equals 1.01325 bar equals 14.6959 psi.

Medical equipment. Blood pressure is universally quoted in mmHg (millimetres of mercury), 120/80 mmHg is the textbook adult normal. Hospital gas pipelines run at about 50 psi (≈ 3.4 bar) for oxygen and about 200 psi for surgical tools.

Common Mistakes

1. Confusing gauge pressure and absolute pressure. A tire that reads "32 psi" on a gauge is 32 psi above the surrounding atmospheric pressure, so its absolute pressure is about 46.7 psi (32 + 14.7). The factors on this page are all gauge pressure factors unless you specifically convert atm; if your source is an absolute-pressure spec, subtract local atmospheric pressure first.
2. Mixing up bar and barg / psig. Engineers sometimes write "bar" when they mean "bar gauge" (barg) and "bar" when they mean "bar absolute" (bara). The numerical difference between the two is always exactly 1.01325 bar (or 14.6959 psi), the local atmosphere.
3. Rounding too early. Many online "psi to bar" tools round to two decimal places, which truncates the fourth-significant-digit precision you need for scuba tanks, hydraulics, and calibration work. This tool rounds to four decimal places, which preserves precision well past anything you can read on a workshop gauge.
4. Using the wrong local atmosphere. 1 atm is defined as 101.325 kPa at sea level under standard gravity, but real weather swings atmospheric pressure by roughly ±3%. If you need high accuracy, use a barometer to measure your local atmospheric pressure rather than assuming 1 atm.
5. Confusing mmHg with mm of water (mmH₂O). These are very different units, 1 mmHg ≈ 13.6 mmH₂O because mercury is about 13.6 times denser than water. The calculator's mmHg field uses the mercury convention; do not enter mmH₂O values into it.

Frequently Asked Questions

What is the exact conversion factor from psi to bar? 1 psi = 0.06894757293168 bar (exact to the limits of double-precision floating point). The rounded value 0.0689476 is accurate to about seven significant figures and is what most engineering references print. 1 bar = 14.5037738 psi (exact, derived from 1 bar = 100 kPa and 1 psi = 6.894757293168 kPa).

Is 1 bar the same as 1 atm? No. 1 bar is exactly 100 kPa, while 1 atm is exactly 101.325 kPa. So 1 atm = 1.01325 bar, and 1 bar ≈ 0.986923 atm. They differ by about 1.3%, small enough to ignore for most workshop gauges but significant for scientific work and for pressure-vessel calibration.

How many psi is atmospheric pressure? Standard atmospheric pressure at sea level (1 atm) is 14.6959488 psi, or about 14.7 psi. Real atmospheric pressure varies with weather and altitude; a typical weather map shows surface pressure between about 14.0 psi (deep low-pressure system) and 15.2 psi (strong high-pressure system).

How many psi should my car tires be? Most passenger-car tires are inflated to 30 to 35 psi (cold) per the door-sticker specification. The same physical pressure expressed in bar is roughly 2.1 to 2.4 bar. Always check the placard on your specific vehicle, load, tire size, and driving style (eco vs sport) all shift the recommended pressure.

What psi do scuba tanks use? Standard aluminium scuba tanks in the US are filled to about 3 000 psi (≈ 207 bar). European steel tanks are typically filled to 200 bar or 232 bar. The exact fill pressure depends on the tank's working-pressure rating stamped on its shoulder.

What is the difference between kPa and MPa? They are the same unit at different scales: 1 MPa = 1 000 kPa. MPa is convenient for high pressures (hydraulic presses, gas pipelines, material testing) where the numbers would otherwise have many digits; kPa is convenient for everyday pressures (tires, atmosphere, residential gas).

Why does the calculator also show mmHg? Millimetres of mercury is the legacy unit for vacuum science, altimeter setting, and medical blood-pressure measurement. It is included because users frequently need to convert between mmHg (vacuum gauges) and psi/bar (workshop gauges) when working with sealed systems and vacuum pumps.

How accurate is this converter? The internal conversion factors are kept to full double-precision (15 to 17 significant digits). Display values are rounded to four decimal places, which preserves roughly seven significant figures, well past the resolution of any workshop gauge and past the calibration accuracy of most industrial sensors.

Can I use this calculator offline? Yes. Once the page has loaded in your browser, the calculator continues to work without an internet connection. The conversion factors are baked into the code; no API calls are made.

Is my data sent anywhere? No. The calculator is purely client-side. Your input values, your results, and your clipboard activity all stay on your device. There is no telemetry, no analytics on field entries, and no server-side processing of any kind.

References

• NIST Special Publication 811, Guide for the Use of the International System of Units (SI). The authoritative US source for the pascal, kilopascal, megapascal, and bar definitions.
• ISO 80000-4:2019, Quantities and units, Part 4: Mechanics. Defines the standard atmosphere (1 atm = 101 325 Pa) and the relationships among psi, bar, kPa, and MPa.
• IUPAC (1993), Quantities, Units and Symbols in Physical Chemistry, 2nd edition (the "Green Book"). Defines the standard atmosphere and the conversion factors used in chemistry and physics.
• BIPM (2019), The International System of Units (SI), 9th edition. Defines the pascal as 1 N/m² and lists the accepted non-SI pressure units (bar, mmHg) and their conversion factors.
• US DOT FMVSS 109 / 119, New-tire placard and tire-pressure specifications, which codify the 30 to 35 psi range for US passenger vehicles.
• ISO 22435, Gas cylinders, Cylinder valves, Specifications and inspection. The international standard for high-pressure cylinder fill pressures used in scuba, fire suppression, and industrial gas.