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Boiling point calculator (altitude & pressure)

Find the boiling point of water at any altitude or atmospheric pressure. Water boils below 100 °C as you climb because the air pushes down less — this tool converts altitude to pressure with the barometric formula, then to a boiling point via the Clausius-Clapeyron relation. Vital for high-altitude cooking and canning.

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Enter Input, Altitude or pressure value, Unit (m/ft for altitude; kPa/atm/psi/mmHg/bar for pressure) and the Boiling point calculator (altitude & pressure) works out Boiling point, Boiling point (°F), Atmospheric pressure (kPa) straight away. For instance, with Input = By altitude, Altitude or pressure value = 1,609 and Unit (m/ft for altitude; kPa/atm/psi/mmHg/bar for pressure) = meters (m) it returns Boiling point = 94.549 °C, Boiling point (°F) = 202.187 and Atmospheric pressure (kPa) = 83.431.

How to use it

  1. Enter your values: Input, Altitude or pressure value, Unit (m/ft for altitude; kPa/atm/psi/mmHg/bar for pressure).
  2. Read the result instantly: Boiling point, Boiling point (°F), Atmospheric pressure (kPa).

Frequently asked questions

How does the Boiling point calculator (altitude & pressure) work?

It takes Input, Altitude or pressure value and Unit (m/ft for altitude; kPa/atm/psi/mmHg/bar for pressure) and derives Boiling point, Boiling point (°F) and Atmospheric pressure (kPa) from them. The calculation is live as you type, so the result updates on every change.

Which values does the calculator ask for?

3 values: Input, Altitude or pressure value and Unit (m/ft for altitude; kPa/atm/psi/mmHg/bar for pressure). Nothing else is required — no account, no file upload.

What does a typical calculation look like?

With Input = By altitude, Altitude or pressure value = 1,609 and Unit (m/ft for altitude; kPa/atm/psi/mmHg/bar for pressure) = meters (m), the calculator returns Boiling point = 94.549 °C, Boiling point (°F) = 202.187 and Atmospheric pressure (kPa) = 83.431. Those figures come from running this exact tool, so you can reproduce them by entering the same values.

How much does the result change with different inputs?

It moves a lot. Using Input = By pressure, Altitude or pressure value = 3,218 and Unit (m/ft for altitude; kPa/atm/psi/mmHg/bar for pressure) = feet (ft) instead, Boiling point goes from 94.549 °C to 233.751 °C — which is why it is worth testing a few scenarios rather than trusting a single figure.

Which “Input” option should I choose?

You can pick between « By altitude » and « By pressure ». Each one changes what the calculator works out, so switch and compare — the default is « By altitude ».

What does it give for smaller values?

Scaled down to Input = By altitude, Altitude or pressure value = 805 and Unit (m/ft for altitude; kPa/atm/psi/mmHg/bar for pressure) = meters (m), Boiling point comes out at 97.278 °C. The relationship is worth checking at both ends before you rely on a single result.

When would I actually use this?

Preparing a solution at a stated concentration, working out how much of a reagent a reaction needs, and converting between mass, moles and volume.

What is the most common mistake?

Confusing molarity with molality. One is per litre of solution and the other per kilogram of solvent; they diverge as concentration rises, and only one of them is temperature-independent.

What is the difference between the Boiling point calculator (altitude & pressure) and the Boiling point elevation calculator?

This one returns Boiling point and Boiling point (°F); the Boiling point elevation calculator returns Boiling point elevation ΔTb and New boiling point. That is the whole difference — open the one whose figure you need.

Is there a tool for the next step?

Osmotic pressure calculator is the closest one after this: Compute osmotic pressure with the van't Hoff equation Π = i·M·R·T — the pressure that drives water across a semipermeable membrane. Enter molarity, temperature and the van't Hoff factor to get the pressure in atmospheres, kilopascals, bar and mmHg. Key to IV fluids, cells and reverse osmosis.

Further reading

All guides →
ExplainerThe Ideal Gas Law Explained: PV = nRT, R in Every Unit, and Where It BreaksPV = nRT holds when the gas is dilute and far from condensing. The value of R depends entirely on the units you feed it, and the temperature is never in degrees Celsius.How-toHow to Calculate a Dilution with C1V1 = C2V2Solve for the missing term, then convert the answer into a bench instruction. The step almost everyone skips is that the solvent you add is V2 minus V1, not V2.ExplainerHow Buoyancy Works: Archimedes' Principle, and Why Ice Floats With 10.5 % Above WaterThe upward force equals the weight of the fluid pushed aside. That one sentence decides whether something floats, and if it floats, exactly how much of it stays under.ExplainerHow Half-Life Works: What Is Left After 1, 3 and 10 Half-LivesOne half-life leaves 50%, three leave 12.5%, ten leave less than a tenth of a percent. The formula is a single line — the part worth understanding is why the answer never reaches zero.How-toHow to Solve Stoichiometry Problems: Grams to Moles to Ratio to GramsEvery problem in the chapter is the same four moves. The mole ratio is the hinge, and it is the step students lose — worked here end to end, limiting reactant and percent yield included.How-toHow to Calculate pH — And When the Weak-Acid Shortcut Stops WorkingFour routes for four kinds of solution, each worked with real numbers. Including the part most pages leave out: the square-root formula for a weak acid is an approximation with a validity limit, and it fails quietly.