⚖️ Comparison · Updated for 2026
Bar vs PSI
Side-by-side comparison, when-to-use-each guide, and instant conversion. Reviewed for 2026.
Quick answer: 1 bar = 14.5 psi. Bar is metric (1 bar ≈ atmospheric pressure at sea level). PSI is imperial. UK car tyres are usually 32-36 psi (2.2-2.5 bar). German owner manuals use bar; American manuals use psi.
Decision guide — when to use which
Use Bar when…
European car manuals (universal), industrial pressure systems in metric countries, scuba diving worldwide.
Use PSI when…
US car manuals, US plumbing and industrial systems, UK car tyres (signs at petrol stations), refrigeration in US.
📊 Side-by-side comparison
| Aspect | Bar | PSI |
|---|---|---|
| Definition | 100,000 pascals (≈ 1 atmosphere) | Pounds per square inch |
| Car tyre typical | 2.2 - 2.5 bar | 32 - 36 psi |
| 1 atmosphere | 1.013 bar | 14.7 psi |
| Scuba diving | 20-30 bar (cylinder) | 2,900-4,400 psi |
Frequently asked
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What's 35 psi in bar?
35 psi = 2.41 bar. Most modern petrol stations in the UK have gauges marked in both, so this matters less than it used to.
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Is bar an SI unit?
No — the SI pressure unit is the pascal (Pa). 1 bar = 100,000 Pa. Bar is widely tolerated alongside SI because the numbers are more practical for engineering.
Reviewed for 2026. All conversion factors and historical references verified against official sources (ISO standards, government weights & measures legislation, IEC technical specifications). Built by a UK-based qualified primary teacher and FA Level 2 coach as part of 247QuickTools' free utility-tools project. We don't sell SEO links or accept paid placements in this content.