Boiling Point Calculator — Any Substance & Pressure
Find the boiling point of common solvents and liquids at any pressure — from vacuum to high pressure — using the Clausius–Clapeyron equation. Results in °C, °F and K.
Substance
kPa
212 °F • 373.15 K
- 1
Convert pressure to Pa
101.325 kPa × 1 000 = 101,325 Pa - 2
ln(P₂/P₁)
ln(101,325 ÷ 101 325) = 0Natural log of pressure ratio; negative when P₂ < P₁ (lower boiling point). - 3
Boiling point in Kelvin (Clausius–Clapeyron)
1 ÷ (1/373.15 − (8.314/40,650) × 0) = 373.15 K - 4
Convert Kelvin to Celsius
373.15 − 273.15 = 100
How does this calculator work?
The boiling point at any pressure is found using the Clausius–Clapeyron equation: T₂ = 1 / [1/T₁ − (R/ΔHvap) × ln(P₂/P₁)]. Select a substance, enter a pressure in kPa (101.325 = 1 atm), and get the boiling point in °C, °F, and K. Lower pressure → lower boiling point; higher pressure → higher boiling point.
Formula
How this is calculated
A liquid boils when its vapour pressure equals the surrounding pressure. At 1 atmosphere (101.325 kPa) each substance has a characteristic normal boiling point; if the pressure changes, the boiling point shifts. The Clausius–Clapeyron equation models this shift by relating two vapour-pressure/temperature pairs through the enthalpy of vaporisation (ΔHvap), the energy required to convert one mole of liquid to vapour.
Rearranging gives T₂ = 1 / [1/T₁ − (R/ΔHvap) × ln(P₂/P₁)], where T is in Kelvin and R = 8.314 J/(mol·K). Increasing pressure pushes the boiling point up; reducing pressure (vacuum) drops it — the basis for vacuum distillation in chemistry labs and food processing. The calculator uses literature values for each substance's normal boiling point and enthalpy of vaporisation.
The equation assumes ΔHvap is constant over the temperature range, which is a good approximation for moderate pressure deviations but becomes less accurate at very high or very low pressures, or near the critical point of a substance.
Frequently asked questions
Atmospheric pressure decreases with altitude. At lower pressure, water molecules need less thermal energy to escape the liquid surface, so the boiling point falls — for example at 2000 m the boiling point of water is about 93°C. See the Boiling Point at Altitude calculator for a dedicated tool.
ΔHvap is the energy (in joules per mole) needed to convert a liquid into vapour at its boiling point. Substances with stronger intermolecular forces (like water with hydrogen bonds) have higher ΔHvap values and thus higher boiling points.
For moderate pressures (roughly 0.1–5 atm) the estimate is typically within 2–5°C of experimental values. Accuracy decreases further from 1 atm because the constant-ΔHvap assumption breaks down and real gases deviate from ideal behaviour.
Also known as
TG we-Calculate Editorial Team. (2026). Boiling Point Calculator — Any Substance & Pressure [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/boiling-point-calculator
TG we-Calculate Editorial Team. "Boiling Point Calculator — Any Substance & Pressure." TG we-Calculate. 2026. https://we-calculate.com/calculator/boiling-point-calculator.
TG we-Calculate Editorial Team, "Boiling Point Calculator — Any Substance & Pressure," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/boiling-point-calculator
@misc{wecalculate_boiling_point_calculator, title = {Boiling Point Calculator — Any Substance & Pressure}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/boiling-point-calculator}}, year = {2026}, note = {TG we-Calculate} }
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