Boiling Point at Altitude Calculator
Enter an elevation to find the atmospheric pressure and water's boiling point there, useful for high-altitude cooking, baking, and hiking.
🏔️ What is Boiling Point at Altitude?
Boiling point at altitude describes how water's boiling temperature drops as elevation increases, because atmospheric pressure falls with elevation. This calculator takes any real-world elevation, converts it into estimated atmospheric pressure using the standard barometric formula, and then applies the Clausius-Clapeyron relation with water's own physical constants to report the exact boiling point there, in both Celsius and Fahrenheit.
This is a genuinely practical, widely searched topic: home cooks in mountain towns need to know how much longer pasta or rice takes to cook, bakers at altitude have to adjust leavening and liquid amounts because water never gets hot enough to set batters the same way it does at sea level, hikers and mountaineers boiling water to purify it need to know it may not reach a temperature that reliably kills all pathogens without extra boiling time, and coffee and tea enthusiasts know that brewing temperature, capped by boiling point, changes extraction at elevation.
A common misconception is that boiling harder or longer makes the water hotter. It does not. Once water reaches its boiling point at a given pressure, it stays at that exact temperature no matter how vigorously it boils, additional heat just makes more steam, it cannot push the liquid water above its pressure-determined boiling point. The only way to get hotter water at altitude is to raise the pressure, which is exactly what a sealed pressure cooker does.
This calculator is useful because manually looking up or estimating atmospheric pressure at a specific elevation, then correctly applying the Clausius-Clapeyron equation with water's real heat of vaporization, is more work than most people want to do before dinner. Enter an elevation in metres or feet and get an instant, physically grounded answer along with the full altitude-versus-boiling-point curve for context.
📐 Formula
📖 How to Use This Calculator
Steps
💡 Example Calculations
Example 1 — Sea Level (Sanity Check)
Altitude = 0 m.
Example 2 — Denver, Colorado ("The Mile-High City")
Altitude = 5,280 ft (one mile).
Example 3 — Mount Everest Summit
Altitude = 8,848 m.
❓ Frequently Asked Questions
🔗 Related Calculators
Why does water boil at a lower temperature at high altitude?
Atmospheric pressure drops as elevation increases, and a liquid boils once its vapor pressure matches the surrounding pressure. Lower surrounding pressure at altitude means water reaches that matching point, and starts boiling, at a lower temperature than the familiar 100 degrees Celsius at sea level.
What temperature does water boil at on Mount Everest?
At the summit of Mount Everest, roughly 8,848 metres, atmospheric pressure is only about 31 kPa (0.31 atm), so water boils at approximately 69 to 70 degrees Celsius, more than 30 degrees below its sea-level boiling point.
At what altitude does high-altitude cooking become noticeable?
Most cookbooks and baking guides start recommending high-altitude adjustments above about 1,000 to 1,500 metres (roughly 3,300 to 5,000 feet), where water's boiling point has already dropped by several degrees, enough to meaningfully slow cooking and change baking chemistry.
Why does food take longer to cook at high altitude?
Cooking speed for boiled or simmered food depends heavily on temperature, not just on whether the water is bubbling. Since water at altitude tops out at a lower temperature, heat transfers into the food more slowly, so the same recipe simply needs more time to reach the same doneness.
How does a pressure cooker help with high-altitude cooking?
A pressure cooker traps steam inside a sealed vessel, letting internal pressure climb well above the reduced outside atmospheric pressure. Because higher pressure raises boiling point, the water inside can reach close to, or even above, its normal sea-level boiling point, restoring much faster cooking times.
What formula estimates atmospheric pressure at a given altitude?
This calculator uses the standard barometric formula for the troposphere, P(h) = 101.325 times (1 minus 2.25577 times 10 to the minus 5 times h) raised to the power 5.25588, with h in metres and pressure in kilopascals, matching the International Civil Aviation Organization's standard atmosphere model.
Does humidity or weather change the boiling point at altitude?
Day-to-day weather causes small fluctuations in local atmospheric pressure, typically only a percent or two, which shifts boiling point by a fraction of a degree. Altitude is by far the dominant factor, weather-driven variation is usually too small to matter for cooking purposes.
Is the boiling point drop the same for every liquid at altitude?
No. Each liquid has its own heat of vaporization, which controls exactly how much its boiling point shifts for a given pressure change. This calculator is specifically built around water's properties, use the general Boiling Point Calculator with a different substance's heat of vaporization for other liquids.
Why does this calculator limit altitude to between about -430 m and 8,850 m?
That range spans the lowest exposed land elevation on Earth, the Dead Sea shore at about -430 metres, up to the summit of Mount Everest at about 8,848 metres, covering every realistic real-world cooking or hiking scenario while staying safely inside the barometric formula's valid range.
How much does boiling point drop per 300 metres (1,000 feet) of elevation gain?
As a rough rule of thumb often used in cooking, boiling point drops by about 1 degree Celsius (roughly 1.8 degrees Fahrenheit) for every 300 metres (about 1,000 feet) of elevation gained, though the true relationship is a curve, not perfectly linear, so this calculator gives the more precise value for any specific elevation.