Boiling Point Altitude
Calculate the boiling point of water at any altitude above sea level. Free online chemistry calculator with pressure readings and interactive charts for hikers, chefs, and scientists.
About This Calculator
The Boiling Point at Altitude Calculator helps you determine the exact temperature at which water boils at any elevation above (or below) sea level. Whether you are a hiker planning a mountain trek, a chef adapting recipes for a high-altitude kitchen, or a student studying atmospheric chemistry, this tool provides accurate results using the standard atmospheric model.
How It Works
Atmospheric pressure decreases predictably as altitude increases. This calculator uses the barometric formula to compute the pressure at your given altitude, then applies the Clausius-Clapeyron relation (approximated by the Antoine equation for water) to determine the corresponding boiling point. The calculation assumes the International Standard Atmosphere (ISA) conditions: sea-level pressure of 1013.25 hPa (29.921 inHg) and a temperature lapse rate of 6.5°C per kilometer.
Key Formulas
Pressure at altitude: P = 29.921 × (1 - 0.0000068753 × h)5.2559 where h is altitude in feet and P is pressure in inHg.
Boiling point from pressure: BP = 49.161 × ln(P) + 44.932 where BP is in degrees Fahrenheit.
Results are displayed in both Celsius and Fahrenheit, with atmospheric pressure in both hPa and inHg.
Regional Notes
India: Many hill stations and Himalayan trekking routes are at significant altitudes. Leh (3,524 m), Shimla (2,205 m), and Darjeeling (2,045 m) all have notably lower boiling points. Hikers in the Himalayas should be aware that water boils at around 87°C at 4,500 meters.
United States: Denver (the Mile High City at 1,609 m / 5,280 ft) has a boiling point of approximately 95°C (203°F). Many mountain towns in Colorado, Utah, and California are above 2,000 m, requiring cooking adjustments. The US standard altitude for high-altitude recipe adjustments typically starts at 3,000 ft (914 m).
United Kingdom: The UK's highest point, Ben Nevis (1,345 m / 4,413 ft), has a boiling point around 96°C (205°F). While most of the UK is near sea level, hillwalkers in the Scottish Highlands and Lake District should account for slightly lower boiling points.
Applications
This calculator is useful for: high-altitude cooking and baking recipe adjustments, determining sterilisation temperatures for camping and hiking, laboratory work at varying elevations, understanding weather and climate effects on phase changes, and educational demonstrations of atmospheric physics.
Frequently Asked Questions
Why does water boil at a lower temperature at higher altitudes?
At higher altitudes, atmospheric pressure is lower. Since boiling occurs when vapor pressure equals ambient pressure, water boils at a lower temperature. At sea level (1013 hPa), water boils at 100°C (212°F), but at 3000 meters (900 hPa), it boils at approximately 90°C (194°F).
What is the boiling point of water at 5000 feet?
At 5000 feet (1524 meters) above sea level, water boils at approximately 94.9°C (202.9°F). The exact value depends on local weather conditions, but this calculator uses the standard atmospheric model to give you an accurate estimate.
How much does boiling point decrease per 1000 feet of altitude gain?
On average, the boiling point of water decreases by about 1°F (0.56°C) for every 500 feet (152 meters) of altitude gain, or approximately 2°C per 1000 feet (305 meters). This is a rough rule of thumb — for precise values, use this calculator.
Is this calculator accurate for cooking at high altitude?
Yes. Chefs and home cooks at high altitudes use the boiling point of water to adjust cooking times and temperatures. Lower boiling points mean food cooks more slowly, so adjustments to time, pressure cooking, or recipe modifications are often needed above 3000 feet (900 meters).
What is the formula used to calculate boiling point at altitude?
The calculator uses two standard formulas from atmospheric science: pressure = 29.921 × (1 - 0.0000068753 × altitude in feet)^5.2559 to get pressure in inHg, and boiling point = 49.161 × ln(pressure) + 44.932 to get the boiling point in °F. Results are then converted to °C and hPa.
Does the boiling point calculator work below sea level?
Yes. For altitudes below sea level (negative values), such as Death Valley (-86 meters) or the Dead Sea (-430 meters), atmospheric pressure is higher than at sea level, so water boils at a temperature above 100°C (212°F).
How does altitude affect cooking times and methods?
At high altitudes, lower boiling points require longer boiling times. For example, at 3000 meters (90°C boiling point), pasta and eggs may need 30-50% more cooking time. Pressure cookers compensate by increasing the internal pressure, raising the boiling point above 100°C regardless of altitude.
Is the boiling point of water the same at all locations at the same altitude?
Not exactly. While altitude is the primary factor, local weather conditions (high/low pressure systems, temperature, humidity) cause small variations of ±1-2°C. However, the standard atmosphere model used in this calculator provides an excellent estimate for most practical purposes.
Can I use this calculator for liquids other than water?
This calculator is specifically calibrated for water. Each substance has its own vapor pressure curve and boiling point at standard pressure. For other liquids, you would need a different set of coefficients in the Antoine equation.