Pressure Converter
Our free pressure converter lets you quickly convert between different pressure units used worldwide. Whether you're working with Pascal, bar, PSI, or atmospheres, this tool provides accurate conversions for engineering, meteorology, industrial applications, or everyday tasks like checking tire pressure.
Important Notes:
- All conversions are based on standard conversion factors and may vary slightly from specialized industry-specific calculations.
- Use scientific notation for very large or small numbers to maintain precision.
- Pressure readings can be affected by altitude, temperature, and other environmental factors.
- For tire pressure, always follow the manufacturer's recommended PSI rather than converting from other units.
- Medical and industrial equipment may require specific pressure units for regulatory compliance.
- This calculator is for informational purposes only and should not be the sole reference for critical applications.
Understanding Pressure Units and Conversions
Pressure is defined as force applied per unit area. Across different industries, regions, and applications, various pressure units have emerged as standards. Understanding how to convert between them is essential for engineers, scientists, technicians, and anyone working with pressure systems.
Common Pressure Units Explained
Pressure units fall into several categories, including metric, imperial, and those derived from atmospheric references:
Metric/SI Pressure Units
- Pascal (Pa): The SI unit, defined as one newton per square meter (N/m²)
- Kilopascal (kPa): 1,000 pascals, commonly used in engineering
- Bar: 100,000 pascals, approximately equal to atmospheric pressure at sea level
- Millibar (mbar): 1/1000 of a bar, frequently used in meteorology
Imperial and Other Pressure Units
- Pounds per square inch (psi): Force in pounds applied to one square inch, common in US and UK
- Atmosphere (atm): Based on standard atmospheric pressure at sea level
- Torr/mmHg: Based on the ability to support a millimeter of mercury in a column
- Inches of mercury (inHg): Used primarily in weather forecasting and aviation in the US
Pressure units often reflect their historical origins in measurement devices like barometers and manometers.
Conversion Factors Between Pressure Units
Converting between pressure units requires specific conversion factors. Here are the most commonly used relationships:
Basic Conversion Relationships
Pascal (Pa) Conversions:
- 1 kPa = 1,000 Pa
- 1 bar = 100,000 Pa
- 1 mbar = 100 Pa
- 1 psi = 6,894.76 Pa
- 1 atm = 101,325 Pa
- 1 Torr = 133.322 Pa
- 1 inHg = 3,386.39 Pa
PSI Conversions:
- 1 psi = 6.895 kPa
- 1 psi = 0.06895 bar
- 1 psi = 68.95 mbar
- 1 psi = 0.068 atm
- 1 psi = 51.715 Torr
- 1 psi = 2.036 inHg
Understanding Pressure Conversion Formulas
To convert between pressure units, multiply the value by the appropriate conversion factor:
Destination Value = Source Value × Conversion Factor
Example: Convert 30 psi to bar
- Conversion factor: 1 psi = 0.06895 bar
- 30 psi × 0.06895 = 2.0685 bar
Example: Convert 1 atm to kPa
- Conversion factor: 1 atm = 101.325 kPa
- 1 atm × 101.325 = 101.325 kPa
Applications of Pressure Measurements
Automotive & Transportation
- Tire pressure: Typically measured in psi (US) or bar/kPa (Europe)
- Engine oil pressure: Often measured in bar or psi
- Fuel systems: Use psi, kPa, or bar depending on region
- Hydraulic systems: Usually measured in bar or psi
- Aircraft altimeters: Based on atmospheric pressure in inHg
For safety, always use the pressure units specified by vehicle manufacturers.
Meteorology & Weather
- Barometric pressure: Measured in inHg (US), mbar or hPa (international)
- Weather forecasting: Tracks pressure systems in millibars
- Storm warnings: Use pressure gradients to predict severity
- Altitude calculations: Based on atmospheric pressure changes
- Climate data: Historical records often use different units by region
A drop in atmospheric pressure often indicates approaching storms.
Industrial & Engineering
- Process control: Often uses bar, psi, or kPa
- Hydraulic systems: Measured in bar, psi, or MPa
- Compressed air: Typically in bar or psi
- HVAC systems: Use psi, inWC (inches water column), or Pa
- Pipelines: Monitor pressure in bar, psi, or kPa
- Vacuum systems: Use Torr, mbar, or Pa
Industrial pressure gauges are often dual-scaled with both metric and imperial units.
Scientific & Medical
- Laboratory equipment: Often uses mbar, Torr, or Pa
- Blood pressure: Measured in mmHg
- Medical gas systems: Use psi, kPa, or bar
- Deep sea research: Calculates pressure in bar or atmospheres
- Materials testing: Uses Pa, MPa, or psi
- Vacuum chambers: Measured in Torr or Pa
Medical applications typically require precise pressure measurements with regular calibration.
Frequently Asked Questions About Pressure Conversion
How do I convert pressure from bar to psi?
To convert from bar to psi, multiply the bar value by 14.5038. For example, 2 bar equals approximately 29.01 psi (2 × 14.5038 = 29.01). The conversion works because 1 bar equals exactly 100,000 pascals, and 1 psi equals approximately 6,894.76 pascals. This relationship gives us the conversion factor of 14.5038 psi per bar.
For a quick estimate, you can use 14.5 as the conversion factor, which is accurate enough for most non-critical applications.
What's the difference between atm and Pa?
Atmosphere (atm) and Pascal (Pa) are both pressure units, but they differ in scale and origin. The Pascal is the SI unit of pressure defined as one newton per square meter (N/m²). It's a relatively small unit named after scientist Blaise Pascal. One atmosphere (atm), on the other hand, is based on the average sea-level atmospheric pressure and equals 101,325 Pa. The atmosphere unit was developed to represent typical environmental pressure, while the Pascal was designed as a standardized scientific measurement.
To convert: 1 atm = 101,325 Pa, or approximately 1.01325 bar.
Can I use this for weather or tire pressure?
Yes, this pressure converter is suitable for both weather and tire pressure applications. For weather, you can convert between millibars (used in international meteorology), inches of mercury (common in US weather reports), and other units. For tire pressure, the tool lets you convert between psi (used in the US and UK) and bar or kPa (common in Europe and many other countries). Just select the appropriate units in the converter and enter your value.
For tire maintenance, remember that manufacturers specify optimal pressures for specific conditions. After converting, round to the nearest practical measurement on your gauge.
Does this tool support scientific or metric conversions?
This converter fully supports both scientific and metric pressure units. It handles metric units like Pascal (Pa), kilopascal (kPa), bar, and millibar, which are part of the International System of Units (SI). It also supports scientific units like torr and technical atmosphere units that are common in laboratory and specialized applications. The scientific notation option is particularly useful for very large Pascal values or very small bar measurements that appear in scientific contexts.
All conversions use precise scientific conversion factors to ensure accuracy across the full range of values.
Can I view pressure in multiple units at once?
Yes, you can view your pressure value converted to multiple units simultaneously. Simply check the "Show all equivalent values" option before performing your conversion. This will display your entered pressure value converted to all supported units (Pascal, kilopascal, bar, millibar, psi, atmosphere, torr/mmHg, and inches of mercury). This feature is particularly useful for educational purposes or when working with international specifications that might reference different pressure units.
You can also copy all these equivalent values at once using the "Copy All Values" button, making it easy to transfer the complete set of conversions to other documents or applications.