Bar to PSI Conversion - bar to psi in One Step

A bar to PSI conversion turns a pressure reading in bar into pounds per square inch (psi), and back, in a single step. It uses the fixed relationship that 1 bar equals exactly 100,000 pascals and 1 psi equals exactly 6,894.757293168 pascals, so 1 bar equals 14.5037738 psi. This covers tire gauges, SCUBA tanks, hydraulic systems, gas-law problems, and engineering datasheets without retyping a constant.

• • Tire pressure and road gauges: Move between bar on European tire placards and the psi values on North American gauges for 2.2 bar car tires, 2.5–3.0 bar bicycle tires, and 4.0+ bar motorcycle and trailer tires.
• • SCUBA and compressed-gas cylinders: Translate a 200 bar or 300 bar fill into the psi rating printed on a regulator or compressor spec sheet without losing precision in the conversion.
• • Hydraulic and pneumatic systems: Convert pump, compressor, and actuator ratings between bar (the European default) and psi (the North American default) for installation manuals and OEM cross-references.
• • Gas-law and engineering textbook problems: Replace textbook bar values with the equivalent psi figure for ideal-gas, van der Waals, and Henry's-law calculations when the rest of the workflow expects psi.

The bar is a metric pressure unit defined by ISO 80000-4 as exactly 100,000 pascals, and the pound per square inch is a US customary unit defined as exactly 6,894.757293168 pascals. The bar to psi ratio is fixed at 100,000 ÷ 6,894.757293168 = 14.5037738, with no measurement uncertainty in the factor itself.

When the answer also needs atm, pascals, or kPa alongside the psi result, the Bar to ATM Conversion Calculator keeps every common bar unit in the same result panel.

The conversion is a single exact ratio. The bar is fixed at 100,000 pascals and the pound per square inch at 6,894.757293168 pascals, so multiplying a bar value by 14.5037738 gives the psi value, and dividing a psi value by 14.5037738 gives the bar value.

• p(bar): Pressure in bar that you want to convert to pounds per square inch
• p(psi): Pressure in pounds per square inch (psi) that you want to convert to bar
• direction: Toggle that picks bar → psi or psi → bar so the same tool handles both directions

When the direction toggle is set to bar → psi, the calculator multiplies the input by 14.5037738 and reports the answer in psi. The same bar value then drives the kPa, atm, and kgf/cm² cross-check rows, so every output reads from a single underlying number.

According to NIST SP 811 (Guide for the Use of SI), 1 bar equals exactly 100,000 pascals and 1 psi equals exactly 6,894.757293168 pascals, which makes the bar to psi ratio 100,000 ÷ 6,894.757293168 = 14.5037738 psi/bar

For the pascal-side panel that also covers atm, kPa, mbar, and bar, the ATM to Pascals Conversion reads the same number against the full SI prefix ladder.

Four ideas shape this conversion: an exact ISO 80000-4 factor for the bar, an exact NIST factor for the psi, the 14.5× magnitude gap between the two units, and the way kPa, atm, and kg/cm² sit on the same physical scale.

When the workflow needs to compare bar and psi against atm, torr, mmHg, and Pa in one entry, a Pressure Converter sits next to the bar to psi conversion as the cross-unit overview.

The bar to psi conversion calculator has a value field and a direction toggle. Pick the direction, type the number, and read the converted pressure plus the kPa, atm, and kg/cm² cross-check rows in the same result panel.

1. 1 Pick the conversion direction: Use the dropdown to switch between Bar (bar) to Pound per square inch (psi) and Pound per square inch (psi) to Bar (bar). The default is bar → psi for the most common tire, SCUBA, and hydraulic workflow.
2. 2 Type the pressure value: Enter the value in the unit set by the direction toggle. Try 1 for a quick sanity check, 2.2 for a typical car tire, 200 for a SCUBA tank fill, or 4.0 for a high-pressure bicycle or motorcycle tire.
3. 3 Read the converted pressure: The black box at the top of the result panel shows the answer in the target unit. For 1 bar, the answer is 14.5037738 psi; for 14.5037738 psi, the answer is 1 bar. The unit label switches with the direction toggle.
4. 4 Cross-check the kPa, atm, and kg/cm² rows: The result panel also shows the same pressure in kilopascals, standard atmospheres, and technical atmospheres (kgf/cm²). Compare against a published chart or a separate calculator to confirm the factor is being applied correctly.
5. 5 Switch direction for the reverse: Toggle the direction dropdown to flip between bar → psi and psi → bar. The same value and cross-check rows are kept, so a round trip takes two clicks and never loses precision.

A European tire placard lists 2.2 bar. Toggle the direction to bar → psi and type 2.2. The calculator returns 31.9083024 psi alongside 220 kPa, 2.1712 atm, and 2.2434 kgf/cm². Toggle to psi → bar and the same value rounds back to 2.2 bar.

For a quick check on the same psi unit when the source is a force-per-area figure in pounds, the Lbs to PSI Calculator reads the pounds value against the matching psi row.

The advantage of a single, factor-driven bar to psi conversion is that the result is exact and the cross-check rows make it self-validating, removing the rounding error and misplaced-decimal mistakes that creep in when each conversion is done by hand.

• • Exact NIST factor: The 1 bar = 14.5037738 psi ratio is fixed by the NIST pascal definitions, so the calculator returns the same value at any precision with no empirical calibration needed.
• • Bidirectional in one tool: Switch the direction toggle to flip between bar → psi and psi → bar. The same input and cross-check rows stay in place, so a round-trip never loses precision.
• • Three cross-check rows: Every result includes the equivalent pressure in kPa, atm, and kgf/cm², catching transcription errors early when a bar value was rounded to 1 or 2 significant figures.
• • Worked tire and SCUBA examples: The 1 bar reference, the 2.2 bar car tire, and the 200 bar SCUBA tank are built into the explanation, covering tire placards, regulator specs, and high-pressure cylinder work.

For a broader psi-side panel that also covers kPa, bar, atm, and MPa, the PSI Conversion Calculator applies the same NIST pascal definitions to the full psi family.

The bar to psi conversion is exact, but the usefulness of any specific number depends on what the input represents, on the precision of the original record, and on whether the rest of the workflow is using the same pressure reference.

• • The bar is not an SI unit, even though it is accepted for use alongside the SI by the BIPM. The SI-recommended unit for the same range is the pascal, and a few engineering datasheets still prefer psi, so always check the unit the rest of the system expects.
• • The conversion factor is exact, but the real pressure being measured is not. A tire pressure of 2.2 bar is a single cold-inflation snapshot, and the actual pressure rises by roughly 0.2 bar when the tire is at operating temperature.

Atmospheric pressure is the most useful benchmark for a real value. At 1.01325 bar, the atmosphere reads 14.696 psi, the same number that anchors US weather reports, altimeter settings, and SCUBA tank ratings.

According to ISO 80000-4:2019, the bar is a non-SI unit accepted for use with the SI and is defined as exactly 100,000 pascals, the value the bar to psi conversion chain uses

For weather and altimeter work where the natural unit is the millibar or hectopascal rather than the psi, the Barometric Pressure Conversion Calculator applies the same 1.01325 bar sea-level standard against mmHg and inHg.