PSI, Bar and kPa Converter for Tyre Pressure
Tyre pressures are quoted in psi, bar or kPa, and your handbook, your gauge and the pump may not use the same one. This converter shows the same pressure in all three. It converts units only: the Highway Code says tyres must be inflated to the vehicle manufacturer’s specification for the load being carried, so use the figure your car maker gives [2].
Last updated: 19 October 2026
How it works
NIST’s conversion tables give 1 bar as exactly 100 kPa. They give 1 psi as 6.894 757 kPa, a figure the table does not mark as exact [1]. The converter turns your value into kPa first and then into the other units:
- kPa = psi × 6.894757
- bar = kPa ÷ 100
- psi = kPa ÷ 6.894757
Results are rounded, so converting back and forth can differ in the last digit.
A worked example
A handbook gives 2.2 bar. That is 220 kPa, and 220 ÷ 6.894757 is about 31.9 psi. Going the other way, a gauge reading of 32 psi is 32 × 6.894757, about 220.6 kPa, which is 2.21 bar.
Illustrative scenario: figures are examples, not quotes, valuations or market prices.
Quick reference
These are conversions computed from the NIST factors, not recommended pressures. Your handbook gives the right figure for your car and load.
| psi | bar | kPa |
|---|---|---|
| 28 | 1.93 | 193.1 |
| 30 | 2.07 | 206.8 |
| 32 | 2.21 | 220.6 |
| 34 | 2.34 | 234.4 |
| 36 | 2.48 | 248.2 |
| 38 | 2.62 | 262.0 |
| 40 | 2.76 | 275.8 |
Using the right pressure
The Highway Code says tyres must be correctly inflated to the vehicle manufacturer’s specification for the load being carried. It says to check pressures weekly, before your journey, while the tyres are cold, because warm or hot tyres may give a misleading reading, and to refer to the vehicle’s handbook or data [2]. Our guide to tyre pressure and tread depth sets out the rules.
What the converter cannot do
- It does not tell you the right pressure. Only your handbook or vehicle data does [2].
- It covers three units. Other units are not included.
- It rounds. Pick more decimal places if you need them.
- Check your gauge. Look at which unit it is showing before you read it against your handbook.
Related terms
Sources
- NIST Guide to the SI, Appendix B.9: Factors for units listed by kind of quantity or field of science (pressure or stress), National Institute of Standards and Technology, nist.gov. The page shows no date. Checked 19 October 2026.
- The Highway Code: Annex 6, Vehicle maintenance, safety and security, GOV.UK. Updated 22 October 2025, gov.uk. Checked 19 October 2026.