Tire Pressure Calculator
Convert tire pressure from PSI (pounds per square inch) to bar — the unit most non-US tire-pressure gauges and vehicle door-jamb stickers use in Europe and most of the world outside the US. Use it when traveling abroad, buying a car spec'd in non-US units, or working with international tire specifications.
Last updated: May 2026
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About this calculator
The formula is: pressure in bar = PSI × 0.0689476. The conversion factor comes from the SI definitions: 1 bar = 100,000 pascals (Pa), and 1 PSI = 6,894.76 Pa, so 1 PSI = 6,894.76 / 100,000 = 0.0689476 bar. Equivalently, 1 bar ≈ 14.5038 PSI. Both PSI and bar are pressure units expressing force per unit area; bar is widely used in Europe for tire pressure (where the typical recommended range is 2.0–2.5 bar = 29–36 PSI), while PSI dominates in the US (where 32–35 PSI is typical for passenger cars). Other common units: kilopascals (kPa) where 1 bar = 100 kPa and tire pressure is often quoted as 200–250 kPa in metric specs; atmospheres (atm) where 1 atm = 1.01325 bar ≈ 14.7 PSI; and millimeters of mercury (mmHg) used in medical and lab contexts but not in tires. Edge cases: zero PSI returns zero bar; negative PSI is physically meaningless (a tire below atmospheric pressure would be deflated below ambient, which doesn't happen). Always inflate tires when cold — pressure rises about 1 PSI per 10°F (or roughly 0.1 bar per 10°C) as the tire heats from driving, so a tire that reads 35 PSI cold may read 38–39 PSI after a half-hour highway drive; the recommended pressure on your door jamb is the cold pressure. Underinflation (below recommended) wears tires faster on the outer edges, increases rolling resistance and fuel consumption by 0.2–0.3% per PSI below spec, and increases the risk of blowouts; overinflation wears the center of the tread faster and produces a harsher ride.
How to use
Example 1 — US sedan to European spec. Your car's door jamb says recommended tire pressure is 33 PSI cold, but you're using a European pressure gauge that reads in bar. Enter 33 for Tire Pressure (PSI). Result: 2.28 bar. Verify: 33 × 0.0689476 = 2.275 bar. ✓ Round to 2.3 bar for the conversion — European gauges typically only display to 0.1 bar resolution, so set the gauge to 2.3 bar (which equals 33.4 PSI, well within typical accuracy tolerance). Example 2 — High-performance car. A sports sedan with stiffer suspension and lower-profile tires often runs higher pressures — 38 PSI cold. Enter 38. Result: 2.62 bar. Verify: 38 × 0.0689476 = 2.620 bar. ✓ At European 2.6 bar (37.7 PSI) or US 38 PSI you're essentially at the same spec; round to whatever your gauge supports. For racing or track-day use, hot pressures may need to be 3–6 PSI lower than street to allow for heat buildup; consult the car manufacturer's track-day pressure recommendations rather than relying on conversion alone.
Frequently asked questions
What is the recommended tire pressure for my car?
Check the door jamb on the driver's side — there's a sticker showing recommended cold tire pressures for front and rear, often in both PSI and kPa (kPa = bar × 100, so 220 kPa = 2.2 bar). The owner's manual also lists them. Do NOT use the maximum pressure printed on the tire sidewall (typically 44 PSI or higher) — that's the tire's safe maximum, not what your specific vehicle wants. Recommended pressures vary by load: passenger cars often spec 32–35 PSI cold for normal driving, with higher pressures (38–42 PSI) when fully loaded with passengers and luggage. Light trucks and SUVs run 35–45 PSI typically. Performance cars and sports sedans often run 38–42 PSI for handling. Underinflation is a much bigger problem than slight overinflation — most tire-related accidents involve significantly underinflated tires.
Why does my tire pressure change with temperature?
Pressure inside a sealed container changes with temperature according to the gas law: pressure is proportional to absolute temperature. The practical rule for car tires is roughly 1 PSI of change per 10°F (or 0.07 bar per 10°C) of ambient temperature change. So a tire set to 35 PSI in summer (75°F) will read about 32–33 PSI on a 45°F autumn morning, even though no air has escaped. This is why TPMS (tire pressure monitoring system) warning lights often come on during the first cold snap of fall — the tires are still safe but have crossed the warning threshold. Re-inflate to spec when seasons change. Driving also heats tires by 30–50°F above ambient, raising pressure by 3–5 PSI; this is normal and is why recommended pressures are always cold-tire values. Don't bleed air out of a hot tire to "correct" the pressure — it will be underinflated when cool again.
How is bar different from kPa?
They're both metric pressure units with a fixed relationship: 1 bar = 100 kPa (kilopascals). Tire pressure quoted as 2.3 bar is identical to 230 kPa. The pascal (Pa) is the SI base unit for pressure (1 newton per square meter); 1 kPa = 1,000 Pa. Bar was introduced as a practical unit for atmospheric and tire pressures where the kPa value is large; 1 standard atmosphere ≈ 1.01325 bar ≈ 101.325 kPa. Modern car owner's manuals often quote both — for example, "2.2 bar / 220 kPa / 32 PSI." Tire pressure gauges in Europe typically display bar with one-decimal precision (e.g., 2.3 bar); kPa gauges show whole numbers (e.g., 230 kPa). The conversion is purely a unit choice; the underlying physical quantity is identical regardless of which unit you read.
What are the most common mistakes people make with tire pressure?
The biggest is checking pressure when tires are warm (after driving) and adjusting to the door-jamb spec — that figure is for COLD tires. The hot tire will read 3–6 PSI higher, so setting to the spec when hot leaves you underinflated when cool. Check first thing in the morning or after the car has sat for 3+ hours. The second is using the max pressure printed on the tire sidewall as the target; that's the maximum the tire can safely hold, not what the car wants. The third is ignoring the TPMS warning until convenient; significant underinflation increases blowout risk and wears tires fast. The fourth is overinflating to improve fuel economy without realizing it produces uneven tread wear (center wears faster than edges) and reduces grip — the gain is minimal and the cost is meaningful. The fifth is forgetting to set spare-tire pressure (which is typically 60 PSI for a compact spare — much higher than main tires); when you need it, an underinflated spare may not be safe to drive on. Finally, people often check pressure only when a TPMS light comes on; monthly visual + gauge checks catch problems before warning thresholds.
When should I not use this calculator?
Skip it if you need to convert to or from units other than PSI and bar — for kPa, multiply bar by 100; for atm, divide bar by 1.01325; for mmHg or torr, multiply PSI by 51.7149. It is the wrong tool for any pressure that isn't tire pressure — for tire-specific decisions (when to inflate, optimal pressure, hot vs. cold), use the manufacturer's door-jamb specification or a tire-pressure recommendation tool. Do not use it for racing or motorsport tire pressures, which depend heavily on track temperature, tire compound, and load and require specific tuning that goes well beyond unit conversion. For bicycle tires (typically 60–120 PSI), motorcycle tires (typically 28–42 PSI), or truck tires (45–100+ PSI depending on load), the conversion math works the same but the relevant ranges differ from passenger cars. And for any safety-critical or commercial-vehicle pressure work, use a calibrated digital gauge and follow the vehicle manufacturer's pressure schedule rather than relying on conversion from another unit.