Pressure Conversion Converter
Convert pressure conversion between units instantly. Includes conversion tables, common equivalents, and calculation formulas.
Reviewed for accuracy by Manoj Kumar, Mathematics Educator
Pressure Conversion Converter
Calculator
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Formula: Target = Value x (Source-to-Pa factor) / (Target-to-Pa factor)
Worked example โ 2.4 bar = 34.81 PSI = 240 kPa = 2.37 atm
Formula
Target = Value x (Source-to-Pa factor) / (Target-to-Pa factor)
All conversions go through pascals as the common base unit. First multiply the input value by its unit factor to get pascals, then divide by the target unit factor. For example, 1 atm = 1 x 101325 Pa, then to PSI: 101325 / 6894.76 = 14.696 PSI.
Worked Examples
Example 1: Converting Tire Pressure Units
Problem:Convert 2.4 bar to PSI, kPa, and atm.
Solution:Pa = 2.4 x 100000 = 240000 Pa PSI = 240000 / 6894.76 = 34.809 PSI kPa = 240000 / 1000 = 240.000 kPa atm = 240000 / 101325 = 2.369 atm
Result:2.4 bar = 34.81 PSI = 240 kPa = 2.37 atm
Example 2: Medical Blood Pressure Conversion
Problem:A systolic reading of 120 mmHg. What is this in kPa and PSI?
Solution:Pa = 120 x 133.322 = 15998.64 Pa kPa = 15998.64 / 1000 = 15.999 kPa PSI = 15998.64 / 6894.76 = 2.320 PSI atm = 15998.64 / 101325 = 0.158 atm
Result:120 mmHg = 16.00 kPa = 2.32 PSI
Frequently Asked Questions
What are the most common pressure units and how do they relate?
The most common pressure units are pascal (Pa), bar, atmosphere (atm), PSI, torr, and mmHg. One standard atmosphere equals 101,325 Pa, 1.01325 bar, 14.696 PSI, 760 torr, and 760 mmHg. The pascal is the SI unit (1 N/m2), while bar is popular in European industrial settings. PSI dominates in American engineering. Torr and mmHg are used in vacuum science and medicine respectively. Each unit emerged from different fields, which is why so many coexist in modern use.
Why are there so many different pressure units?
Different pressure units developed independently across various fields and countries. The pascal came from the SI system in 1971. The atmosphere was defined by the pressure at sea level. The torr originated from mercury barometer measurements in the 1600s. PSI developed from the imperial system used in America and Britain. The bar was created as a convenient metric unit close to atmospheric pressure. Each field adopted the unit most convenient for its typical pressure ranges, and legacy usage keeps them all in active use today.
What is gauge pressure versus absolute pressure?
Absolute pressure measures from a perfect vacuum (zero point), while gauge pressure measures relative to the local atmospheric pressure. At sea level, atmospheric pressure is about 101.325 kPa (14.696 PSI), so a tire gauge reading 32 PSI (gauge) actually means 46.7 PSI absolute. Gauge pressure can be negative (vacuum), while absolute pressure is always positive. Units are sometimes suffixed with "a" for absolute (psia) or "g" for gauge (psig). Scientific calculations typically require absolute pressure.
How do I choose the right pressure unit for my application?
Use pascals or kilopascals for scientific work and international standards. Use bar for European industrial applications and meteorology (as hectopascals). Use PSI for American automotive, HVAC, and industrial applications. Use torr or millitorr for vacuum science and semiconductor manufacturing. Use mmHg for blood pressure and medical applications. Use atmospheres for chemistry and diving calculations. When in doubt, the pascal is always correct as the SI unit, and any other unit can be derived from it.
How do significant figures affect unit conversions?
Your converted result should have the same number of significant figures as your original measurement. If you measure 5.2 inches (2 significant figures), converting to centimeters gives 13 cm, not 13.208 cm. Using excessive decimal places implies false precision.
What are the most common unit conversion mistakes?
Common errors include confusing fluid ounces with weight ounces, mixing up miles and nautical miles, forgetting that UK and US gallons differ (UK is 20% larger), using the wrong temperature formula, and not accounting for the difference between troy and avoirdupois ounces.
How precise should my unit conversions be?
Match precision to your application. Cooking tolerates rough conversions (1 cup is about 240 mL). Engineering may need 4-6 decimal places. Scientific work requires exact conversion factors and proper significant figure handling. More precision than your measurement accuracy is meaningless.
References
Reviewed for accuracy by Manoj Kumar, Mathematics Educator ยท Editorial policy
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