About

Pressure measurement is fundamental across a vast range of disciplines, including engineering, meteorology, diving, and automotive maintenance. However, different fields have adopted different units as their standard, creating a confusing landscape of Pascals, bars, PSI, and atmospheres. This tool eliminates the need to perform multiple, single-purpose conversions. It functions as a central dashboard where a single input value is instantly converted into all major pressure units simultaneously.

This one-to-many approach is designed for efficiency. An engineer can input a value in Pascals (Pa), the SI standard, and immediately see the equivalent in Pounds per Square Inch (psi) for a US-based component specification. A meteorologist can enter atmospheric pressure in millibars and see the equivalent in Torr for calibrating an older instrument. By providing a comprehensive overview in one action, the tool saves time and reduces the risk of error from repeated calculations.

Formulas

All conversions are performed by first converting the input unit to the SI base unit of Pascals (Pa), and then converting from Pascals to all other target units. The key conversion factors relative to 1 Pascal are:

1 Pa = 1 Nm²

1 bar = 100,000 Pa

1 atm = 101,325 Pa

1 psi ≈ 6,894.757 Pa

1 Torr ≈ 133.322 Pa

Reference Data

Condition	Pascal (Pa)	Bar	Atmosphere (atm)	PSI	Torr
Standard Sea Level	101,325	1.01325	1	14.696	760
Typical Car Tire (Gauge)	220,632	2.206	2.177	32	1655
Mars Surface Avg.	610	0.0061	0.006	0.088	4.575
Lab "High Vacuum"	10⁻⁴	10⁻⁹	9.87 × 10⁻¹⁰	1.45 × 10⁻⁸	7.5 × 10⁻⁷
Espresso Machine	900,000	9	8.882	130.5	6751
Pressure Washer	13,789,500	137.9	136.1	2000	103,434

Frequently Asked Questions

The official SI (International System of Units) unit for pressure is the Pascal (Pa), which is defined as one newton of force per square meter (N/m²). It is the base unit used for all calculations in this tool.

Many pressure units arose from different historical contexts and for specific applications. For example, "atmospheres" was based on the average atmospheric pressure at sea level, "millimeters of mercury" (Torr) came from early barometer designs, and "PSI" was developed in engineering fields where forces (pounds) and areas (square inches) were common.

Absolute pressure is measured relative to a perfect vacuum (0 Pa). Gauge pressure is measured relative to the local atmospheric pressure. For example, a car tire gauge might read 32 psi, but its absolute pressure is that value plus the atmospheric pressure (around 14.7 psi), totaling 46.7 psi. This tool converts the numerical value you provide, assuming it is absolute unless you account for the difference.

For most practical purposes, yes. The two units are nearly identical (1 Torr = 0.9999998575 mmHg). The Torr was defined to be exactly 1/760 of a standard atmosphere, which simplifies the relationship.