Quick answer
Pressure units convert through pascals. 1 bar equals 14.5038 psi, 100 kPa and 0.98692 atm.
Enter a value and choose the units. The calculator returns the converted pressure.
Related tools: Pressure Calculator: Pressure from force and area, with unit conversions. Partial Pressure Calculator: Partial pressure of a gas in a mixture (Dalton's law).
How to use the Pressure Converter
- Enter value.
- Choose from: Pascal (Pa), Kilopascal (kPa), Megapascal (MPa), Bar, Millibar (mbar) and Standard atmosphere (atm) and 8 more.
- Choose to: Pascal (Pa), Kilopascal (kPa), Megapascal (MPa), Bar, Millibar (mbar) and Standard atmosphere (atm) and 8 more.
- Enter decimal places (between 0 and 10). It starts at 4.
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Value | A number | — |
| From | Choose one: Pascal (Pa); Kilopascal (kPa); Megapascal (MPa); Bar; Millibar (mbar); Standard atmosphere (atm); Pound per square inch (psi); Torr; … | Starts at Pascal (Pa) |
| To | Choose one: Pascal (Pa); Kilopascal (kPa); Megapascal (MPa); Bar; Millibar (mbar); Standard atmosphere (atm); Pound per square inch (psi); Torr; … | Starts at Kilopascal (kPa) |
| Decimal places | A number | ≥ 0, ≤ 10, starts at 4 |
Formula and method
Formula
result = value × (factor of source ÷ factor of target), base unit: pascal
IEEE-754 double precision; displayed to the chosen number of decimal places (default 4). Very small or large results are shown in scientific notation.
Every unit is defined by an exact or published factor to the base unit (pascal). The value is multiplied by the source factor and divided by the target factor.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Value = 1; From = Bar; To = Pound per square inch (psi); Decimal places = 4.
| Result | Value |
|---|---|
| Bar → Pound per square inch (psi) | 14.5038 |
| Input | 1 Bar |
Example 2
Inputs: Value = 1; From = Standard atmosphere (atm); To = Kilopascal (kPa); Decimal places = 3.
| Result | Value |
|---|---|
| Standard atmosphere (atm) → Kilopascal (kPa) | 101.325 |
| Input | 1 Standard atmosphere (atm) |
Example 3
Inputs: Value = 760; From = Torr; To = Standard atmosphere (atm); Decimal places = 4.
| Result | Value |
|---|---|
| Torr → Standard atmosphere (atm) | 1 |
| Input | 760 Torr |
The first line is the headline result (bar → Pound per square inch (psi)). Below it the pressure Converter lists input, which describe the same case from other angles. IEEE-754 double precision; displayed to the chosen number of decimal places (default 4). Very small or large results are shown in scientific notation.
Unit reference
Each unit expressed in the base unit used for the calculation. Conversions go through this base unit, so any unit can be converted to any other in the table.
| Unit | Equals (in pascal) |
|---|---|
| Pascal (Pa) | 1 |
| Kilopascal (kPa) | 1000 |
| Megapascal (MPa) | 1000000 |
| Bar | 100000 |
| Millibar (mbar) | 100 |
| Standard atmosphere (atm) | 101325 |
| Pound per square inch (psi) | 6894.757293 |
| Torr | 133.3223684 |
| Millimetre of mercury (mmHg) | 133.3223874 |
| Inch of mercury (inHg) | 3386.38864 |
| Hectopascal (hPa) | 100 |
| Kilogram-force per square centimetre (kgf/cm²) | 98066.5 |
| Kilogram-force per square metre (kgf/m²) | 9.80665 |
| Pound per square foot (psf) | 47.88025898 |
Key equivalents
1 atm = 101.325 kPa = 14.696 psi = 760 mmHg. 1 psi = 6.895 kPa. A tire at 32 psi is 2.2 bar.
Gauge versus absolute
Tire and boiler gauges show pressure above atmospheric (gauge), while physics uses absolute pressure. Absolute equals gauge plus about 14.7 psi at sea level.
How the result changes with value
Holding every other input at the first worked example, this table changes only value. It shows how sensitive the answer is to that one value; each row was produced by running this calculator.
| Value | Bar → Pound per square inch (psi) | Input |
|---|---|---|
| 0.5 | 7.2519 | 0.5 Bar |
| 1 | 14.5038 | 1 Bar |
| 2 | 29.0075 | 2 Bar |
| 4 | 58.0151 | 4 Bar |
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Value: left empty shows "Enter value." beside that field and no result.
Choosing between the Pressure Converter and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Pressure Calculator](/science/pressure-calculator/) | force and area | Pressure |
| [Partial Pressure Calculator](/science/partial-pressure/) | total pressure, moles of the gas and total moles of all gases | Partial pressure |
| [Mean Arterial Pressure Calculator](/health/mean-arterial-pressure/) | systolic and diastolic | Mean arterial pressure |
| [Pipe Pressure Drop Calculator](/engineering/pipe-pressure-drop-calculator/) | flow, inside diameter and length | Pressure drop |
| [Volume Converter](/converters/volume-converter/) | value, from and to | US gallon → Litre (L) |
Background: unit conversion
Many customary units are defined exactly in terms of metric ones: since the 1959 International Yard and Pound Agreement an inch is exactly 2.54 cm and a pound is exactly 0.45359237 kg (NIST SP 811 lists these). So most length and mass conversions are exact apart from the rounding of the displayed result.
To convert, multiply the value by the source unit's factor to reach the base unit, then divide by the target unit's factor; the unit table on this page lists every factor used. Temperature and fuel economy are the exceptions, because they are not simple multiples.
Assumptions and limitations
- Negative values are allowed
- Zero converts to zero (except L/100 km, where zero is invalid)
- Units from different quantities cannot be converted
- Very large or tiny results switch to exponent notation
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for value to confirm this.
Frequently asked questions
How many psi is 2 bar?
2 bar is about 29.0 psi, since 1 bar = 14.5038 psi.
What is a pascal?
One newton per square metre.
How many mmHg in an atmosphere?
One standard atmosphere is 760 mmHg, equal to 101.325 kPa or 14.696 psi.
What does the Pressure Converter calculate?
Convert pascals, bar, psi, atmospheres, torr and mmHg. It returns Bar → Pound per square inch (psi) and Input.
What formula does the Pressure Converter use?
result = value × (factor of source ÷ factor of target), base unit: pascal. Every unit is defined by an exact or published factor to the base unit (pascal).
What is an example of a pressure result?
With value 1, from Bar, to Pound per square inch (psi) and decimal places 4, the bar → Pound per square inch (psi) is 14.5038.
Where does the method come from?
The method follows: NIST SP 811 (2008): standard atmosphere = 101 325 Pa exactly; psi = 0.45359237 kg × 9.80665 m/s² / (0.0254 m)² = 6894.757293168 Pa.
Related calculators
- Pressure Calculator — Pressure from force and area, with unit conversions.
- Partial Pressure Calculator — Partial pressure of a gas in a mixture (Dalton's law).
- Volume Converter — Convert litres, gallons, cups, spoons and more.
- Weight Converter — Convert kilograms, pounds, ounces, stone and more.
Sources
- NIST SP 811 (2008): standard atmosphere = 101 325 Pa exactly
- psi = 0.45359237 kg × 9.80665 m/s² / (0.0254 m)² = 6894.757293168 Pa
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.