At higher altitudes, atmospheric pressure is lower because there is less air above pressing down. Water boils when its vapor pressure equals the surrounding atmospheric pressure. With lower air pressure, water molecules need less energy (heat) to escape into the air as steam, so boiling occurs at a lower temperature. For every approximately 300 meters (1,000 feet) of elevation gain, the boiling point drops by about 1°C (1.8°F).

As a general rule, the boiling point of water decreases by approximately 1°C (1.8°F) for every 300 meters (about 1,000 feet) of elevation gain above sea level. For example, at 5,000 feet (1,524 m), water boils at around 95°C (203°F) instead of 100°C (212°F). At 10,000 feet (3,048 m), the boiling point drops to approximately 90°C (194°F). This relationship is nearly linear for elevations up to about 3,000 meters.

Because water boils at a lower temperature at altitude, foods cooked in boiling water (like pasta, rice, or boiled eggs) take longer to cook. As a guideline, for every 300 meters (1,000 feet) above sea level, increase boiling-based cooking time by about 5-10%. At 1,500 meters (5,000 feet), you may need to increase cooking time by 25-50%. For precise cooking, use a food thermometer to ensure safe internal temperatures. Pressure cookers are excellent solutions for high-altitude cooking as they raise the boiling point.

It depends on the tea type and your altitude. Green and white teas (ideal at 70-85°C) are actually easier to brew at high altitudes because boiled water naturally cools into their optimal range quickly. However, black tea, pu-erh, and some oolongs that require near-boiling water (95-100°C) become challenging above 1,500 meters where water boils below 95°C. In such cases, use a pressure cooker to heat water beyond the local boiling point, or steep the tea longer to compensate for the lower temperature. A vacuum-insulated thermos can also help maintain temperature during steeping.

The Dead Sea sits at approximately 430 meters (1,410 feet) below sea level—the lowest land point on Earth. At this elevation, atmospheric pressure is higher than at sea level (about 1065 hPa vs. 1013 hPa), causing water to boil at approximately 101.5°C (214.7°F). While this slightly higher boiling point won't dramatically affect cooking, it does mean water takes marginally longer to reach a rolling boil and food cooks at a slightly higher temperature.

This calculator uses the International Standard Atmosphere (ISA) model to estimate atmospheric pressure at a given altitude, then applies the Antoine equation for water's vapor pressure to determine the precise boiling point. The results are accurate to within ±0.2°C for elevations between -500 m and 6,000 m under standard atmospheric conditions. Note that actual boiling points may vary slightly due to weather conditions (high/low pressure systems), humidity, and local geographic factors. For most cooking and tea-brewing purposes, this accuracy is more than sufficient.

A standard pot lid does not significantly change the boiling point because it does not create a sealed, pressurized environment. However, it does trap steam and heat, which can make water boil slightly faster and maintain a more vigorous boil. A pressure cooker, on the other hand, creates a sealed environment that increases internal pressure, raising the boiling point significantly—making it an excellent tool for high-altitude cooking where the natural boiling point is too low for certain foods or tea preparations.

Water temperature dramatically affects flavor extraction in tea and the texture of cooked foods. Tea brewed at too low a temperature may taste weak and under-extracted, while some delicate green teas become bitter if steeped in water that's too hot. For cooking, lower boiling temperatures mean longer cooking times for items like pasta, beans, and boiled eggs. Understanding your local boiling point helps you adjust brewing techniques and cooking methods for consistently excellent results, whether you're at sea level or in a mountain city like Denver or La Paz.