Pressure Converter - Convert psi, bar, kPa, atm, torr, mmHg & More
Free online pressure unit converter. Instantly convert between Pascal (Pa), kilopascal (kPa), bar, millibar (mbar), standard atmosphere (atm), pounds per square inch (psi), torr, mmHg, inHg, mmH₂O, inH₂O, and more. Accurate to 6 decimal places.
Input Pressure
Converted Pressure
What Is a Pressure Converter and Why Do You Need One?
A pressure converter (also called a pressure unit calculator or pressure conversion tool) instantly translates measurements between different units of pressure. Pressure is defined as force per unit area and is a critical parameter in physics, engineering, meteorology, diving, automotive systems, hydraulics, and countless industrial processes. Whether you need to convert psi to bar, convert kPa to psi, convert atm to mmHg, or handle specialized units like torr, inches of mercury (inHg), or millimeters of water (mmH₂O), this free pressure conversion calculator provides accurate, instant results.
Pressure measurements appear everywhere: car tire pressure (psi or bar), blood pressure (mmHg), weather reports (mbar or inHg), SCUBA tank pressure (psi or bar), hydraulic systems (MPa or psi), and vacuum systems (torr). However, different countries, industries, and applications use wildly different units. The United States primarily uses psi (pounds per square inch), while Europe uses bar and kilopascal (kPa). Meteorology uses millibar (mbar) or hectopascal (hPa). Medicine uses millimeters of mercury (mmHg). Vacuum physics uses torr. Without a reliable online pressure converter, comparing data across these systems is error‑prone.
This free pressure unit converter operates entirely within your browser - no data is sent to any server, ensuring your privacy and enabling offline use. It supports 13 pressure units: Pascal (Pa), kilopascal (kPa), megapascal (MPa), bar, millibar (mbar), standard atmosphere (atm), psi, psf, torr, mmHg, inHg, mmH₂O, and inH₂O. Whether you are a mechanic inflating tires, a diver calculating bottom pressure, a meteorologist reading weather charts, an HVAC technician checking refrigerant pressures, or a student solving physics problems, this tool is your go‑to solution.
How to Use This Free Online Pressure Converter
Using this psi to bar converter is simple. Follow these steps to get accurate conversions instantly:
- Enter the value: Type the numeric pressure value you wish to convert. The tool accepts positive numbers, decimals, and large values up to 10¹⁵.
- Select the source unit: Choose the unit of your input value from the "From Unit" dropdown menu. Options include Pa, kPa, MPa, bar, mbar, atm, psi, psf, torr, mmHg, inHg, mmH₂O, and inH₂O.
- Select the target unit: Choose the unit you want to convert to from the "To Unit" dropdown.
- View the result: The converted value appears instantly in the output panel. You can copy the result to your clipboard with a single click.
- Use additional features: Click "Swap Units" to reverse the conversion direction, "Clear" to reset all fields, or the fullscreen button for an expanded view.
The bar to psi converter automatically performs conversions as you type, so you don't need to click a separate convert button unless you prefer manual control. Your recent selections are saved locally for up to 30 days, making it easy to continue your work across sessions.
All Supported Pressure Units - Complete Reference Table
Our pressure unit converter supports 13 pressure units spanning metric, imperial, atmospheric, mercury‑column, and water‑column systems. Below is a complete reference table showing each unit, its symbol, exact conversion factor to Pascals (Pa), and typical applications.
| Unit | Symbol | Value in Pa (exact) | Common Applications |
|---|---|---|---|
| Pascal | Pa | 1 | SI base unit; low pressures, stress analysis |
| Kilopascal | kPa | 1,000 | Engineering, building codes, tyre pressure (rest of world) |
| Megapascal | MPa | 1,000,000 | Material strength (concrete, steel), hydraulic systems |
| Bar | bar | 100,000 | Tyre pressure (Europe), diving, industrial processes |
| Millibar | mbar | 100 | Meteorology (weather maps), aviation |
| Standard Atmosphere | atm | 101,325 | Reference pressure; chemistry, scuba decompression |
| Pound per square inch | psi | 6,894.757 | Tyre pressure (US), plumbing, air tools, hydraulics |
| Pound per square foot | psf | 47.88026 | Structural loads (wind, snow), roofing |
| Torr | Torr | 133.3224 | Vacuum measurement, low‑pressure physics |
| Millimeter of mercury | mmHg | 133.3224 | Blood pressure, barometers, medical devices |
| Inch of mercury | inHg | 3,386.389 | Aviation altimeters, weather reports (US) |
| Millimeter of water | mmH₂O | 9.80665 | Low pressures, ventilation, medical ventilators |
| Inch of water | inH₂O | 249.089 | HVAC static pressure, gas appliance testing |
Understanding Pressure Units - From Pascals to Atmospheres
Pascal (Pa) and Multiples (kPa, MPa) - The SI Standard
The Pascal (Pa) is the SI unit of pressure, defined as one newton per square meter. It is a relatively small unit - standard atmospheric pressure is about 101,325 Pa. For everyday use, kilopascal (1 kPa = 1,000 Pa) is more common. Tyre pressures are often specified in kPa (e.g., 220 kPa). For high pressures in material science and hydraulic systems, megapascals (1 MPa = 1,000,000 Pa) are used. Concrete strength, for example, is often rated at 20‑40 MPa. To convert kPa to psi, multiply by 0.145038.
Bar and Millibar - Meteorology and Engineering
The bar is a metric unit but not an SI unit; 1 bar = 100,000 Pa = 100 kPa. It is very close to standard atmospheric pressure (1.01325 bar). Bar is widely used in Europe for tyre pressure, in SCUBA diving (dive computers), and in industrial process control. The millibar (mbar), equal to 1 hPa (hectopascal), is the standard for atmospheric pressure in weather maps. Sea‑level pressure is typically around 1013 mbar. To convert bar to psi, multiply by 14.5038.
Pounds per Square Inch (psi) - The US Standard
Pounds per square inch (psi) is the most common pressure unit in the United States for everyday applications: tyre pressure (30‑40 psi), air compressors (100‑150 psi), water pressure (40‑60 psi), and hydraulic systems (2,000‑5,000 psi). One psi is approximately 6,895 Pa. To convert psi to bar, divide by 14.5038. For larger pressures, kilopounds per square inch (ksi) is used in structural engineering.
Atmosphere (atm) - Standard Reference Pressure
The standard atmosphere (atm) is defined as exactly 101,325 Pa (101.325 kPa, 1.01325 bar, 14.6959 psi). It represents the average atmospheric pressure at sea level. It is commonly used in chemistry (gas laws), physics, and SCUBA diving to express pressures in multiples of the atmospheric pressure (e.g., 3 atm means three times sea‑level pressure). To convert atm to psi, multiply by 14.6959.
mmHg, Torr, inHg - Mercury Column Units
Millimeters of mercury (mmHg) and torr are nearly identical (1 mmHg ≈ 1 torr). They are derived from the height of a mercury column that a pressure can support. Blood pressure is measured in mmHg (e.g., 120/80 mmHg). Vacuum systems and low‑pressure experiments use torr (1 torr = 1/760 atm). Inches of mercury (inHg) is used in US aviation altimeters and weather barometers (e.g., 29.92 inHg at sea level). To convert mmHg to psi, multiply by 0.0193368.
mmH₂O and inH₂O - Water Column Units
Water column units are used for very low pressures, such as HVAC static pressure, gas appliance pressure, and liquid level measurement. Millimeters of water (mmH₂O) and inches of water (inH₂O) are common. Positive airway pressure machines (CPAP) use cmH₂O; 1 cmH₂O = 10 mmH₂O. In HVAC, duct pressures are often measured in inH₂O (e.g., 0.5 inH₂O). To convert mmH₂O to Pa, multiply by 9.80665.
Common Pressure Conversions - Quick Reference Formulas
Metric ↔ Metric
- kPa → Pa: multiply by 1,000
- MPa → kPa: multiply by 1,000
- bar → kPa: multiply by 100
- mbar → Pa: multiply by 100
- Pa → kPa: divide by 1,000
- kPa → MPa: divide by 1,000
psi ↔ Metric
- psi → bar: multiply by 0.0689476
- bar → psi: multiply by 14.5038
- psi → kPa: multiply by 6.89476
- kPa → psi: multiply by 0.145038
- psi → atm: divide by 14.6959
Atmospheres, mmHg, inHg
- atm → kPa: multiply by 101.325
- atm → mmHg: multiply by 760
- mmHg → kPa: multiply by 0.133322
- inHg → kPa: multiply by 3.38639
- torr → Pa: multiply by 133.322
Water Column Conversions
- mmH₂O → Pa: multiply by 9.80665
- inH₂O → Pa: multiply by 249.089
- mmH₂O → inH₂O: divide by 25.4
- inH₂O → psi: divide by 27.6799
- mmH₂O → kPa: divide by 101.972
Real-World Applications of Pressure Conversion
Understanding how to convert between pressure units is essential across many fields. Here are real-world scenarios where our pressure calculator proves invaluable:
Automotive Tyre Inflation
Car tyre pressures vary by region: US spec sheets list psi, European cars often use bar. A US driver traveling to Canada with a European car needs to convert bar to psi at the air pump. Our converter gives the correct pressure instantly, preventing under‑ or over‑inflation.
SCUBA Diving
Dive computers and tank pressure gauges may show bar (common in Europe) or psi (US). A dive shop in Mexico might use bar, but a diver from the US is used to psi. Converting tank pressure ensures accurate remaining air calculations.
HVAC and Refrigeration
HVAC technicians measure refrigerant pressures in psi, bar, or kPa depending on the equipment's origin. Static pressure in ductwork is often measured in inches of water column (inH₂O). Our converter helps professionals quickly switch between units for troubleshooting and charging systems.
Medical Applications
Blood pressure readings are always in mmHg, but some electronic monitors can show kPa. Breathing circuits and ventilators use cmH₂O or mmH₂O. Our pressure converter ensures accurate interpretation of medical data.
Frequently Asked Questions (FAQ) About Pressure Conversion
How do I convert psi to bar?
To convert psi to bar, multiply the psi value by 0.0689476. For example, 35 psi × 0.0689476 = 2.413 bar. Conversely, to convert bar to psi, multiply by 14.5038. Our tool does this instantly.
What is the difference between gauge pressure and absolute pressure?
Gauge pressure (psig, barg) measures pressure relative to atmospheric pressure. Absolute pressure (psia, bara) includes atmospheric pressure. Absolute pressure = gauge pressure + atmospheric pressure (≈14.7 psi at sea level). Our converter handles absolute pressure units; for gauge conversions, add or subtract atmospheric pressure manually.
How many kPa are in 1 bar?
One bar equals exactly 100 kPa (kilopascal). This is a simple metric relationship: 1 bar = 100,000 Pa = 100 kPa.
How accurate is this pressure converter?
Our converter uses internationally recognized exact conversion factors (e.g., 1 atm = 101,325 Pa exactly). Results are displayed to 6 decimal places, providing accuracy suitable for engineering, medical, and scientific applications.
Can I use this pressure converter offline?
Yes. Once the page has loaded, all conversion logic runs locally in your browser. No internet connection is required after initial load - perfect for field use or areas with poor connectivity.
What is normal atmospheric pressure in psi, bar, and mmHg?
Standard atmospheric pressure at sea level is approximately:
• 14.7 psi
• 1.01325 bar (or 1013.25 mbar)
• 760 mmHg (or 760 torr)
• 29.92 inHg
• 101.325 kPa
Why Choose Our Pressure Converter Over Others?
- Completely free, no registration. Unlimited pressure conversions with no barriers.
- Privacy‑first design. All calculations happen locally in your browser. Your data never leaves your device.
- Supports 13 pressure units - including rare but essential units like torr, mmH₂O, and inH₂O.
- High precision with results to 6 decimal places, suitable for engineering and medical use.
- User‑friendly features including unit swap, fullscreen mode, one‑click copy, and local save of recent selections.
- Works offline after initial page load.
- Fully responsive design with resizable panels on desktop for custom workflow.
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