Water boiling point calculator

Water boils when its saturation pressure equals the surrounding absolute pressure. This calculator numerically inverts the IAPWS saturation-pressure correlation. At 101.325 kPa, the correlation gives about 99.9743°C on the modern temperature scale, commonly rounded to 100°C.

Reference: IAPWS saturation properties

The result above uses these exact values. This snapshot is included when the page is printed so the output can be checked against the original measurements.

Absolute local pressure

101.325 kPa

Primary result: Water saturation temperature: 99.97429581 °C.

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Pure water liquid-vapour equilibrium only, from just above 0.611657 kPa through 22064 kPa, corresponding to the triple point through the critical point. Enter local absolute pressure, not sea-level-adjusted weather pressure or gauge pressure. Dissolved substances, superheating and heat-transfer rates are not modelled.