Convert between 23 pressure units including Pascal, PSI, Bar, Atmosphere, plus specialized tools and downloadable charts
This comprehensive pressure converter helps you convert between 23 different pressure units used in engineering, science, and industry. Whether you're working with Pascal (the SI unit), PSI for American applications, Bar for European standards, or specialized units like mmHg for medical applications, our calculator provides instant, accurate conversions.
Our tool is designed to meet the needs of students, professionals, and anyone requiring reliable pressure conversions. All calculations use internationally recognized conversion factors and are accurate to six decimal places. The calculator includes specialized tools for tire pressure and altitude calculations, plus downloadable reference charts for offline use.
Our pressure converter uses internationally recognized conversion factors based on the definitions established by the International Bureau of Weights and Measures (BIPM) and the International System of Units (SI).
1 Pascal = 1 Newton per square meter (N/m²)
All conversions are calculated relative to Pascal, the SI base unit for pressure.
| Unit | Symbol | Conversion to Pascal | Common Use |
|---|---|---|---|
| Pascal | Pa | 1 Pa = 1 Pa | SI unit, scientific applications |
| Kilopascal | kPa | 1 kPa = 1,000 Pa | Engineering, HVAC systems |
| Megapascal | MPa | 1 MPa = 1,000,000 Pa | Structural engineering, materials |
| Atmosphere | atm | 1 atm = 101,325 Pa | Standard atmospheric pressure |
| Bar | bar | 1 bar = 100,000 Pa | European pressure measurements |
| Pound per Square Inch | psi | 1 psi = 6,894.757 Pa | US engineering applications |
| Millimeter of Mercury | mmHg | 1 mmHg = 133.322 Pa | Medical and vacuum applications |
| Hectopascal | hPa | 1 hPa = 100 Pa | Weather forecasting |
| Millibar | mbar | 1 mbar = 100 Pa | Meteorology |
| Torr | Torr | 1 Torr = 133.322 Pa | Vacuum technology |
Precision Level: Our calculator uses conversion factors accurate to 6 decimal places, providing precision suitable for most engineering and scientific applications.
Standard References: All conversion factors are based on the 2019 redefinition of SI base units and internationally accepted standards.
Rounding: Results are displayed with appropriate significant figures based on the input precision, with a maximum of 6 decimal places.
Pressure is defined as force applied perpendicular to a surface per unit area. In mathematical terms, pressure equals force divided by area (P = F/A). This fundamental concept applies across numerous fields, from atmospheric science to hydraulic engineering, making pressure conversion an essential skill for students and professionals alike.
The variety of pressure units exists because different industries and regions developed their own standards based on practical applications. Understanding these units and their relationships helps ensure accuracy in calculations and clear communication across disciplines.
The Pascal (Pa), named after French mathematician Blaise Pascal, is the SI unit for pressure. One Pascal equals one Newton per square meter (N/m²), making it directly related to fundamental SI units. While Pascal provides a consistent scientific standard, its relatively small magnitude often requires prefixes like kilopascal (kPa) or megapascal (MPa) for practical applications.
In engineering contexts, you'll frequently encounter kilopascals when dealing with structural loads, tire pressures, or HVAC systems. Atmospheric pressure at sea level is approximately 101.3 kPa, providing a useful reference point for everyday pressure measurements.
Pounds per square inch (PSI) remains the dominant pressure unit in American engineering and manufacturing. This unit's practical size makes it ideal for applications like tire pressure (typically 30-35 PSI), hydraulic systems (often 1000-5000 PSI), and compressed air systems (commonly 80-120 PSI).
PSI's popularity in the United States stems from its integration with the imperial measurement system and its convenient magnitude for common applications. When working with international partners or scientific publications, converting between PSI and metric units becomes crucial for accurate communication.
The Bar, while not an official SI unit, gained widespread acceptance in European industry due to its practical size and simple relationship to atmospheric pressure. One Bar equals 100,000 Pascal and approximately equals atmospheric pressure (1.013 Bar at sea level).
European automotive manufacturers typically specify tire pressures in Bar, while hydraulic equipment manufacturers often use Bar for pressure ratings. The millibar (mbar) is commonly used in meteorology, where atmospheric pressure variations are measured in small increments.
Atmosphere (atm): Based on standard atmospheric pressure at sea level, the atmosphere unit provides intuitive understanding for pressure measurements. Scuba divers use atmospheres to describe depth-related pressure increases, where each 10 meters of depth adds approximately one atmosphere of pressure.
mmHg and Torr: These units, based on mercury column height, remain standard in medical applications. Blood pressure measurements use mmHg because early pressure measurement devices used mercury columns. Understanding that normal blood pressure (120/80) represents 120 mmHg systolic and 80 mmHg diastolic pressure helps contextualize these measurements.
Inches of Water (inH₂O): HVAC professionals commonly use inches of water column for measuring small pressure differences in ventilation systems. This unit provides appropriate sensitivity for measuring pressure drops across filters, dampers, and ductwork.
Understanding the difference between absolute and gauge pressure is crucial for accurate pressure measurements and conversions. Absolute pressure measures pressure relative to a perfect vacuum (zero pressure), while gauge pressure measures pressure relative to atmospheric pressure.
Most pressure gauges read gauge pressure, meaning they show zero when exposed to atmospheric pressure. When converting between units, ensure you're working with the same pressure reference. Engineering applications often specify whether pressures are absolute (PSIA, bara) or gauge (PSIG, barg).
Several common errors can compromise pressure conversion accuracy:
Unit Confusion: Always verify whether you're working with absolute or gauge pressure. Converting PSIG to kPa requires different calculations than converting PSIA to kPa.
Significant Figures: Maintain appropriate precision in your conversions. Converting a measurement given to two decimal places to six decimal places implies false precision and can mislead subsequent calculations.
Temperature Effects: Remember that pressure measurements can be temperature-dependent. Gas pressures vary with temperature according to gas laws, so specify measurement conditions when precision matters.
Automotive Industry: Tire pressure specifications vary by region, with American manufacturers using PSI and European manufacturers using Bar. Understanding both units helps when traveling or working with international vehicles.
Medical Field: Blood pressure measurements universally use mmHg, while respiratory therapy equipment may use cmH₂O or mbar for ventilator pressures. Medical professionals must accurately convert between units when using equipment from different manufacturers.
Aerospace Engineering: Aircraft altimeters use atmospheric pressure changes to determine altitude, requiring precise understanding of pressure-altitude relationships. Cabin pressurization systems maintain specific pressure levels measured in various units depending on the aircraft manufacturer.
While digital calculators provide convenience, understanding the underlying mathematics enables verification of results and troubleshooting of discrepancies. Cross-checking conversions using multiple methods or references helps ensure accuracy in critical applications.
Professional engineering work often requires documented conversion methods and uncertainty analyses. Understanding conversion factor sources and their precision limitations helps assess overall measurement uncertainty in complex systems.
The 2019 redefinition of SI base units, including the Pascal's foundation in fundamental constants, ensures long-term stability and accuracy in pressure measurements. This standardization supports increasingly precise scientific research and industrial applications requiring exceptional accuracy.
As international collaboration continues growing, understanding multiple pressure unit systems becomes increasingly valuable. Whether you're a student learning physics principles or a professional working across international boundaries, mastering pressure unit conversions enhances your technical capabilities and communication effectiveness.
Access our comprehensive pressure conversion reference charts for offline use in laboratories, workshops, and field applications.
Common pressure units with conversion factors. Perfect for desk reference.
All 23 pressure units with detailed conversion factors and examples.
Practice problems with conversion exercises for students and professionals.
💡 Pro Tip: Save these charts to your phone or print them for quick reference in the field. All conversion factors are sourced from NIST and BIPM standards.
Professional calculators for specific pressure applications in automotive, aviation, and environmental monitoring.
Convert between PSI, Bar, and kPa for automotive, motorcycle, and bicycle tires.
Calculate atmospheric pressure at different altitudes for aviation and meteorology.
Absolute pressure is measured relative to a perfect vacuum (zero pressure), while gauge pressure is measured relative to atmospheric pressure. Most pressure gauges read gauge pressure, showing zero when exposed to atmospheric pressure. When converting between units, always verify whether you're working with absolute or gauge pressure, as this affects the conversion calculations.
Our calculator uses internationally recognized conversion factors accurate to 6 decimal places, based on standards from the International Bureau of Weights and Measures (BIPM). This precision level is suitable for most engineering and scientific applications. Results are displayed with appropriate significant figures based on your input precision.
Pascal (Pa) is the official SI unit used globally in scientific applications. PSI is predominant in the United States for engineering and industrial applications. Bar is widely used in Europe for industrial applications. mmHg is universally used in medical applications for blood pressure measurements. The choice often depends on your industry, location, and application requirements.
Different pressure units developed historically based on practical measurement methods and regional preferences. For example, mmHg originated from mercury barometers, PSI from imperial measurements, and Bar for convenient atmospheric pressure reference. Each unit serves specific applications where its magnitude and familiarity provide practical advantages.
Yes, this calculator works for vacuum measurements when using absolute pressure units. Vacuum levels are often expressed as absolute pressures below atmospheric pressure. However, be aware that vacuum applications sometimes use specialized units like Torr (equivalent to mmHg) or microns of mercury for very low pressures.
Atmospheric pressure decreases with altitude due to the reduced weight of air above. At sea level, standard atmospheric pressure is 101.325 kPa (14.696 PSI). Pressure drops approximately 12% for every 1000 meters of elevation gain. This relationship is crucial for applications like aircraft altimeters and pressure-sensitive equipment used at various elevations.
Temperature significantly affects gas pressure according to gas laws. For enclosed gases, pressure increases with temperature when volume remains constant. However, this calculator converts between pressure units at any given condition - temperature effects would need to be calculated separately using appropriate gas law equations if you're analyzing pressure changes due to temperature variations.
Explore our other conversion calculators designed to help with your engineering and scientific calculations:
About ConversionCalculator.net: We provide accurate, easy-to-use conversion tools for students, professionals, and anyone needing reliable unit conversions. All our calculators are designed with precision, accessibility, and user experience in mind.
Educational and Informational Use: This pressure conversion calculator is provided for educational, informational, and general reference purposes only. While we strive for accuracy, the results should not be used as the sole basis for critical engineering, medical, or safety decisions.
All conversion factors are sourced from internationally recognized standards including the International Bureau of Weights and Measures (BIPM) and the National Institute of Standards and Technology (NIST). Results are calculated to 6 decimal places for maximum precision. However, users should verify critical calculations independently using multiple sources.
For professional engineering, medical, scientific, or industrial applications, always:
ConversionCalculator.net, its authors, and contributors shall not be held liable for any direct, indirect, incidental, special, or consequential damages arising from the use of this calculator or its results. Users assume full responsibility for verifying the accuracy and appropriateness of conversions for their specific applications.
This calculator performs all calculations client-side in your browser. No personal data, calculations, or results are transmitted to our servers or stored in any database. Your privacy and data security are fully protected.
While we regularly review and update our conversion factors to maintain accuracy, standards and definitions may change over time. Users requiring the most current standards should consult the latest publications from relevant standards organizations.
The specialized tools (tire pressure and altitude calculators) use standard formulas and assumptions. For critical applications such as aviation, automotive safety, or precision manufacturing, always use equipment-specific data and professional consultation.