What conversion factors are used for tire pressure units?

Per NIST SP 811: 1 bar equals exactly 100 kPa; 1 psi equals 6.894757 kPa (~0.06894757 bar); and 1 kgf/cm² equals exactly 98.0665 kPa (0.980665 bar or ~14.2233 psi).

Where should I look to find my vehicle correct tire pressure?

Always refer to the vehicle placard affixed to the driver side door jamb, pillar, or fuel filler door, as well as the owner manual. Never use the pressure stamped on the tire sidewall; the sidewall indicates the maximum permissible inflation pressure of the tire casing, not the vehicle manufacturer design specification.

When is a tire considered cold for accurate pressure measurement?

According to NHTSA TireWise guidance, measure pressure when the tires are cold—meaning the vehicle has not been driven for at least three hours.

Why does tire pressure change after driving?

Internal tire temperature rises during driving due to sidewall flexing and road friction. In accordance with the ideal gas law, heated air inside the sealed tire expands, increasing gauge pressure. You should never bleed air from a hot tire to match cold placard specifications.

Are kg/cm² and bar the exact same unit?

No. While often treated as roughly interchangeable on older consumer gauges, 1 kgf/cm² is 98.0665 kPa (0.980665 bar), making 1 bar approximately 1.97% greater than 1 kgf/cm².

Tire Pressure Converter

Convert tire pressure instantly between PSI, bar, kPa, and kgf/cm² with precise NIST ratios, quick-fill common values, and a dynamic nearby step table.

Pressure Unit Converter

Enter a value in any unit. All fields synchronize instantly.

Quick Entry Values (Not Recommendations)

Choose only a value shown on your vehicle placard or owner manual.

PSI (lbf/in²)

PSI

bar (100 kPa)

bar

kPa (kilopascals)

kPa

kgf/cm² (technical atmosphere)

kgf/cm²

Gauge Neighbor Stepping Chart

Values ±5 PSI around active setting for quick air pump dial alignment.

PSI	bar	kPa	kgf/cm²

Unit Equivalents & Scientific Ratios

Calculations conform to National Institute of Standards and Technology (NIST SP 811) SI conversion standards:

1 bar = 100 kPa (exact)

1 bar ≈ 14.503774 PSI

1 PSI = 6.894757 kPa

1 kgf/cm² = 98.0665 kPa (exact)

Safety Limitations & Cold Pressure Guidelines

Placard vs. Sidewall: Always inflate to the pressure specified on your vehicle door jamb or owner manual. The number stamped on the tire sidewall is the tire maximum permissible inflation pressure, not the vehicle manufacturer recommendation.
Cold Definition (NHTSA): Measure pressure when tires are cold—defined by NHTSA TireWise as not having been driven for at least three hours.
Axle & Load Variances: Do not rely on generic charts. Front and rear axle specifications frequently differ based on vehicle weight distribution and towing conditions.

Summary

Convert tire pressure instantly between PSI, bar, kPa, and kgf/cm² with precise NIST ratios, quick-fill common values, and a dynamic nearby step table.

How it works

Enter any pressure reading into PSI, bar, kPa, or kgf/cm².
All counterpart units recalculate instantly via NIST conversion constants.
Use the common pressure chips to test standard placard numbers with one click.
Consult the dynamic gauge stepping chart to find adjacent markings on analogue air chucks.
Use Reset to clear all fields or Copy All to save the current conversion set.

Use cases

Converting European vehicle door placard specifications (bar) to service station inflator gauges (PSI).
Translating Japanese or Korean domestic specification sheets (kPa) to bar or PSI.
Checking analog tire pressure gauges graduated in kgf/cm² against modern vehicle placards.
Interpolating nearby pressure gauge marks when inflating tires in fractional bar or PSI increments.

Frequently Asked Questions

Last updated: 2026-09-22 · Reviewed by Nham Vu