Pressure Converter
Convert pressure units for tires, diving, weather, HVAC, and industrial systems: Pa, kPa, bar, psi, atm, mmHg, inHg, and torr.
Tire PSI, Diving Bar, and Clinical mmHg
BrainyCalculators editorial insight — unique to this tool
US drivers inflate car tires to 32–35 psi (≈ 220–240 kPa) while EU pump gauges show bar (1 bar ≈ 14.5 psi). Scuba tables and cylinder ratings use bar; hyperbaric medicine references atmospheres (1 atm = 101.325 kPa). Blood pressure is measured in mmHg (120/80 mmHg ≈ 16/10.7 kPa) — a unit legacy from mercury manometers that persists in cardiology worldwide.
When to use this calculator
Convert pressure units for tires, HVAC refrigerant specs, hydraulics, weather (hPa), or medical context — not for force or weight.
| Reference | Value | Context |
|---|---|---|
| Standard atmosphere | 101.325 kPa | 1 atm / 1.013 bar |
| Typical car tire | 32 psi | ≈ 2.2 bar |
| Normal BP (systolic) | 120 mmHg | ≈ 16 kPa |
| Scuba tank fill | 200 bar | ≈ 2,900 psi |
Not what you need? For beam loads or structural stress in MPa from engineering formulas, start with Force or Beam Deflection calculators.
Converting litres, gallons, or cubic metres?
This page converts pressure units (psi, bar, kPa, mmHg). For fluid capacity — fuel tanks, recipe cups, concrete yd³ — use the Volume Converter →
What is Pressure Conversion?
Pressure conversion translates force per unit area between units such as pascals, kilopascals, bar, psi, atmospheres, mmHg, inHg, and torr. It is used for tire pressure, dive tanks, blood pressure, weather reports, HVAC ducts, and process equipment.
Use this page when the input is a pressure reading you already have. It converts units; it does not calculate flow, volume, temperature effects, or gas-law behavior from first principles.
For liters, gallons, or cubic meters, use the Volume Converter. For mass such as kg or lb, use the Weight Converter.
Tyre, Dive, and HVAC Pressure Math
Conversions pass through pascals. Tyre gauges read gauge pressure (relative to atmosphere); thermodynamic gas laws often need absolute pressure — add ~101 kPa at sea level when required.
Pressure Anchors for Tyres, Weather, and Clinics
How the Pressure Converter Works
Formula, assumptions, and calculation steps for this conversion tool.
Methodology
Conversion calculators multiply by fixed conversion factors after identifying the source and destination units.
Calculation Steps
- Choose the input unit and output unit.
- Enter the amount to convert.
- Apply the standard conversion factor.
- Return the converted value with unit labels.
Assumptions and Limits
- Conversions use standard factors unless a regional variant is selected.
- Rounding is applied for readability.
- Temperature and pressure conversions may require formulas rather than simple multiplication.
Frequently Asked Questions
32 psi ≈ 2.21 bar or 221 kPa. European pumps and placards often show bar while US door stickers list psi.
Clinical tradition standardised on millimetres of mercury. 120 mmHg systolic equals about 16.0 kPa even though SI uses pascals elsewhere.
Yes numerically: 1 hPa = 1 mbar. Weather maps near 1,013 hPa are reporting standard sea-level pressure.
Gauge readings ignore atmospheric pressure; absolute readings include it. Tyre gauges read gauge pressure, so 32 psig is about 46.7 psia at sea level.
A 3,000 psi fill is about 207 bar. Always check whether the cylinder rating and fill station use the same unit before connecting gear.
Real-World Applications
Pressure Conversion Mistakes to Avoid
Pressure Unit Conversion Quick Reference
| Unit | Symbol | Equivalent in Pa |
|---|---|---|
| Pascal | Pa | 1 Pa |
| Kilopascal | kPa | 1,000 Pa |
| Bar | bar | 100,000 Pa |
| Atmosphere | atm | 101,325 Pa |
| PSI | psi | 6,894.76 Pa |
| mmHg / Torr | mmHg | 133.322 Pa |
| inHg | inHg | 3,386.39 Pa |
References
- BIPM. The International System of Units (SI), 9th Edition. Bureau International des Poids et Mesures, 2019.
- ISO 80000-4. Quantities and Units — Part 4: Mechanics. ISO, 2019.
- NIST. Guide to the SI — Special Publication 811. National Institute of Standards and Technology, 2008.
- Engineering Toolbox. Pressure Units — Conversion Factors. engineeringtoolbox.com, 2024.
- ASHRAE. HVAC Applications Handbook. American Society of Heating, Refrigerating and Air-Conditioning Engineers, 2023.
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