Pressure Converter

1. 01Enter a value and its unitType the number and select which pressure unit it is currently in.
2. 02Read the converted valuesEvery other supported unit updates automatically.
3. 03Note negative valuesA negative number is treated as a valid vacuum or below-reference gauge reading (common on vacuum gauges), not rejected as invalid input.

• Checking tire pressure across unitsConvert a tire-pressure spec given in psi to bar or kPa, or the reverse, when a vehicle manual and a pressure gauge use different units.
• Reading a weather or altitude reportConvert atmospheric pressure readings between atm, hPa/kPa, and torr for weather, aviation, or altitude-related reference.
• Working with an engineering or scientific specConvert between SI pressure units (Pa, kPa, MPa) and bar or psi when a datasheet uses a different unit than your own calculations.

• 1 bar = 100,000 PaThe bar is defined as exactly 100,000 pascals — a round, SI-adjacent unit commonly used for tire pressure and weather reporting.
• 1 atm ≈ 14.6959 psiStandard atmospheric pressure (1 atm, defined as exactly 101,325 Pa) is approximately 14.6959 pounds per square inch.
• 1 atm = 760 torr, exactlyThe torr is defined as exactly 1/760 of a standard atmosphere, making the atm-to-torr conversion exact by definition.

This tool uses exact, internationally defined constants: 1 bar = 100,000 Pa; 1 atm = 101,325 Pa (the internationally defined standard atmosphere); 1 torr = 1/760 atm; and 1 psi = 4.4482216152605 N / 0.00064516 m² ≈ 6894.757293168361 Pa, derived from the exact definitions of the pound-force and the square inch. Every conversion is computed through one canonical internal unit (pascals) with no intermediate rounding, so chained or round-trip conversions do not drift.

Torr and mmHg are treated as the same value here, which matches common practice. They are technically defined slightly differently (mmHg through the historical density of mercury at standard gravity, torr as an exact fraction of a standard atmosphere), but the difference is smaller than 0.000015% — far below the precision needed for any practical use.

This is a linear unit converter, not a gauge-vs-absolute-pressure calculator. A negative input is converted the same way as a positive one and represents a legitimate reading below the reference point (common on vacuum gauges, for example, where "-5 psi" is a normal reading), not an error condition.

What is the exact psi-to-Pa conversion?

1 psi = 6894.757293168361 Pa, derived exactly from the international definitions of the pound-force (4.4482216152605 N) and the square inch (0.00064516 m²) — not a rounded approximation.

Is 1 bar the same as 1 atm?

No, though they are close. 1 bar = 100,000 Pa exactly, while 1 atm = 101,325 Pa exactly — about 1.3% higher than 1 bar.

Are torr and mmHg exactly the same unit?

They are extremely close but not defined identically — the difference is under 0.000015%, which this tool treats as equivalent, matching standard practice.

Why can the result be negative?

This tool converts pressure values linearly in either direction. A negative number is a valid gauge-pressure reading below the reference point (for example, on a vacuum gauge), so it is converted, not rejected.

Is my data saved?

No. Everything is calculated in your browser; nothing is sent to a server.