Pressure Converter — PSI, Bar, kPa, MPa, atm & More

The Formula

Pressure unit conversion uses a linear factor relative to the Pascal (Pa), the SI base unit of pressure. Each unit is converted to Pascals first, then divided by the target unit's Pascal factor. For example, converting 1 PSI to bar: 1 PSI × 6894.76 Pa/psi ÷ 100,000 Pa/bar = 0.0689 bar.

Variable Definitions

How to Use This Calculator

1. 1

   Enter the numeric pressure value you want to convert in the "Value" field.

2. 2

   Select the unit you are converting from in the "From" dropdown (e.g., PSI, bar, kPa).

3. 3

   Select the unit you want to convert to in the "To" dropdown.

4. 4

   The result is displayed instantly along with the conversion formula.

5. 5

   Use the quick reference table below for common conversions like tire pressure (PSI ↔ bar) or blood pressure (mmHg ↔ kPa).

Quick Reference

Common Applications

• Tire pressure: 30–35 PSI (2.1–2.4 bar) for most passenger cars
• Blood pressure: ~120/80 mmHg (systolic/diastolic)
• Scuba tanks: 2,000–3,000 PSI (138–207 bar)
• Atmospheric pressure at sea level: 14.7 PSI / 1.013 bar / 1013 hPa
• HVAC refrigerant pressures: 60–150 PSI depending on refrigerant type
• Hydraulic systems: 1,000–5,000 PSI (69–345 bar) for industrial equipment

Gauge pressure reads zero at atmosphere; absolute pressure = gauge + atmospheric

Understanding the Concept

Pressure is a fundamental measurement in physics, engineering, meteorology, and medicine — defined as force per unit area. The SI unit is the Pascal (Pa), but dozens of legacy units remain in active use around the world. Tire pressure gauges use PSI in the United States, weather reports use hectopascals (hPa) in Europe and millibars elsewhere, blood pressure is measured in millimeters of mercury (mmHg), and industrial processes use bars or megapascals. This converter handles all major pressure units with exact conversion factors. Understanding pressure units is essential for automotive maintenance, scuba diving, HVAC work, hydraulic systems, weather monitoring, and aerospace engineering. For example, standard sea-level atmospheric pressure is 14.7 PSI, 1013.25 hPa, 29.92 inHg, or 1 atm — all describing the same physical quantity. The Mars Climate Orbiter disaster (1999) was caused partly by a unit mismatch in thruster calibration data, highlighting how critical precise pressure and force unit conversion can be.

Frequently Asked Questions

Sources & References