Pressure Converter
Convert between Pa, kPa, bar, psi, atm and mmHg.
PSI
14.503768
from 1 Bar
Pascal (Pa)
100,000
Kilopascal (kPa)
100
Bar
1
Atmosphere (atm)
0.986923
mmHg (torr)
750.063755
AI Breakdown & Smart Takeaway
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How the Pressure Converter works
This pressure converter instantly converts values between the most widely used pressure units — Pascal (Pa), kilopascal (kPa), bar, psi, atm, and mmHg — making it essential for engineers, students, medical professionals, and anyone working across unit systems.
Pressure is defined as force applied perpendicularly per unit area. Every pressure unit is simply a different-sized 'measuring stick' for this same physical quantity. The Pascal (Pa), the SI base unit, is the foundation: one Pascal equals one Newton per square meter (1 N/m²). All conversions in this tool work by first expressing your input value in Pascals, then multiplying by the precise conversion factor for the target unit. This two-step normalization approach guarantees accuracy no matter which unit pair you're converting between.
The six supported units span a wide range of practical scales. Pascals and kilopascals dominate scientific and engineering contexts, with kPa being 1,000 Pa. The bar (used heavily in European industry and meteorology) is very close to one standard atmosphere, at exactly 100,000 Pa. The psi (pounds per square inch) is the everyday unit in the United States for tire pressure, blood pressure equipment calibration, and hydraulic systems — one psi equals approximately 6,894.76 Pa. The standard atmosphere (atm) represents average sea-level air pressure and is widely used in chemistry and diving. Finally, mmHg (millimeters of mercury) — also called Torr in most contexts — is the clinical standard for blood pressure and barometric readings, where 1 mmHg equals 133.322 Pa.
A common mistake users make is confusing gauge pressure with absolute pressure. Absolute pressure is measured relative to a perfect vacuum (zero pressure), while gauge pressure is measured relative to current atmospheric pressure (~101,325 Pa or 14.696 psi). Tire pressure ratings and many industrial sensors report gauge pressure, meaning a tire listed at 32 psi gauge is actually 46.7 psi absolute. This converter works with absolute pressure values; if you are dealing with gauge readings, mentally add ~1 atm (or 14.696 psi / 101.325 kPa) before converting if your application requires absolute values.
For best results, consider the precision requirements of your field. Medical applications (blood pressure in mmHg) typically need one decimal place, while pneumatic engineering may demand four or more significant figures in psi or bar. If you are converting from a very small unit like Pa to atm, the resulting number will be tiny — scientific notation may be more readable. Always verify your converted value is physically reasonable: atmospheric pressure at sea level is roughly 101.3 kPa, 1.013 bar, 14.7 psi, 1 atm, or 760 mmHg, and these benchmarks serve as quick sanity checks.
Formula
Conversion formula: Target Value = Input Value × (Input Unit in Pa) ÷ (Target Unit in Pa) Key reference factors (in Pa): 1 Pa = 1, 1 kPa = 1,000, 1 bar = 100,000, 1 psi = 6,894.757, 1 atm = 101,325, 1 mmHg = 133.322
Pro tips
- Use 101.325 kPa, 14.696 psi, 1 atm, 1.01325 bar, and 760 mmHg as your mental benchmarks for sea-level atmosphere — if a converted result is wildly off from these relationships, recheck your input.
- When converting tire pressures from a US psi rating to bar for a European trip, remember the gauge-vs-absolute distinction: a US gauge rating of 35 psi converts to approximately 2.41 bar gauge — do not add atmospheric pressure unless your gauge explicitly reads absolute.
- For blood pressure conversions, mmHg is the universal clinical unit; if a device outputs kPa (common in some automated monitors), multiply by 7.5006 to get mmHg — a systolic reading of 16 kPa is approximately 120 mmHg.
- In high-precision engineering work (hydraulics, aerospace), use the full Pa value as an intermediate step and round only at the final output to prevent cascading rounding errors across multiple conversion steps.
- When working with weather data, note that meteorologists often report pressure in hPa (hectopascals), where 1 hPa = 1 mbar = 100 Pa — a standard day is about 1013.25 hPa, which you can enter as 101,325 Pa in this converter.
Key terms
- Pascal (Pa)
- — The SI base unit of pressure, defined as one Newton of force applied over one square meter of area.
- psi (pounds per square inch)
- — An imperial pressure unit equal to one pound-force applied per square inch, widely used in the US for tire pressure, hydraulics, and industrial applications.
- Bar
- — A metric pressure unit equal to exactly 100,000 Pascals, commonly used in European industry, meteorology, and fluid dynamics.
- Standard Atmosphere (atm)
- — A unit defined as exactly 101,325 Pa, representing the average atmospheric pressure at sea level and used as a reference in chemistry and scuba diving.
- mmHg (Millimeter of Mercury)
- — A pressure unit equal to the pressure exerted by a 1 mm column of mercury (133.322 Pa), the international clinical standard for blood pressure measurement.
- Gauge vs. Absolute Pressure
- — Absolute pressure is measured from a perfect vacuum, while gauge pressure is measured relative to current ambient atmospheric pressure — a critical distinction when using this converter for real-world sensor readings.
