Tool · water temperature

Coffee temperature converter + altitude boiling point

Brewing guides quote temperatures in °F or °C, and most assume your kettle boils at 212 °F. Convert any temperature below, then enter your elevation to see where water actually boils there and how that compares with the Specialty Coffee Association’s brewing band.

Updated 2026-10-17 · sources listed at the end · runs in your browser; nothing is stored or sent

How the converter works

The temperature half is the exact definition. NIST’s Guide to the SI gives t/°C = (t/°F − 32)/1.8, and the kelvin value follows from T/K = (t/°F + 459.67)/1.8, which is the same as adding 273.15 to the Celsius figure. Dividing by 1.8 is the same as multiplying by 5/9.

The altitude half takes two steps, because water boils where its vapor pressure equals the air pressure around it (Wikipedia, Atmospheric pressure). Lower pressure means a lower boiling point.

1. Pressure from elevation. The National Weather Service gives pressure altitude in feet as 145366.45 × [1 − (P/1013.25)^0.190284], with P in millibars (hPa) and 1013.25 the standard sea-level pressure. Solved for P, that gives the standard-atmosphere pressure at any elevation: about 843 hPa at 5,000 ft. The inHg figure uses 1013.25 hPa = 29.92 inHg.
2. Boiling point from pressure. The NIST Chemistry WebBook lists Antoine-equation parameters for water: log₁₀(P) = A − B/(T + C), with P in bar and T in kelvin. For 344–373 K (about 71–100 °C) it gives A = 5.08354, B = 1663.125, C = −45.622, calculated by NIST from Bridgeman and Aldrich (1964). Rearranged: T = B/(A − log₁₀P) − C. At 1.01325 bar it returns 100.00 °C.

Boiling point by altitude

Computed with the formula above, next to the 1 °F-per-500 ft rule of thumb (“Rule”) and the published figures. The Wikipedia table (credited there to NASA, using the NOAA standard atmosphere) and the USDA Food Safety and Inspection Service both assume standard conditions.

The formula stays within 0.5 °F of the Wikipedia table at every row and matches FSIS’s 208 °F at 2,000 ft and “about 198 °F” at 7,500 ft. FSIS puts the drop at “just under 1 °F” per 500 ft; the formula gives 0.91 °F for the first 500 ft, so the straight-line rule runs about 1.7 °F too cool by 10,000 ft and 2.5 °F by 15,000 ft.

What it means for brewing

The SCA recommends water at the point of contact with coffee of 200 °F ± 5° (93.0 °C ± 3°), and its cupping protocol adds that “temperature needs to be adjusted to elevation.” Under standard conditions the formula puts boiling water at:

• Below about 3,800 ft — above 205 °F, so there is room to let water cool off the boil. The National Coffee Association suggests resting boiled water about a minute for pour-over and about 30 seconds for French press, both aiming at 93 ± 3 °C.
• About 3,800 to 9,300 ft — inside the 195–205 °F band; it reaches 200 °F near 6,600 ft. Resting it first, as the NCA suggests, moves it toward or below the 195 °F floor, so check with a thermometer.
• Above about 9,300 ft — below 195 °F even at a full boil. Brew straight off the boil; the water temperature guide covers compensating with grind size and contact time.

The SCA’s two versions of the target do not convert exactly into each other: 195–205 °F is 90.6–96.1 °C, while 93 ± 3 °C is 194.0–204.8 °F. The differences are under 1 °F.

Brewing temperatures in °F and °C

Method-by-method targets, including espresso and French press ranges, are on the water temperature page; the AeroPress guide lists competition recipes, each with its own water temperature.

Limits of the approximation

• Weather. The calculation uses the standard atmosphere, but real pressure moves with the weather; Wikipedia’s pressure article notes sea-level readings from 870 hPa in tropical cyclones to about 1,085 hPa in strong highs. With the same Antoine equation, a 990 hPa low at sea level boils water at 99.35 °C (210.8 °F) and a 1,030 hPa high at 100.46 °C (212.8 °F).
• Model assumptions. The standard atmosphere assumes a fixed lapse rate, dry air and constant gravity; the barometric formula grows less precise at higher elevations.
• Equation range. The Antoine parameters are fitted for 344–373 K. Below sea level the boiling point rises slightly above 373 K, so results there are a small extrapolation; the calculator accepts −1,500 to 20,000 ft and flags anything outside 0–15,000 ft.
• Pure water. The equation describes pure water; it says nothing about how fast a kettle cools or how much heat the brewer and grounds absorb.

Quick checklist

1. Convert the recipe’s temperature with the converter if it uses the other scale.
2. Enter your elevation and compare the boiling point with the recipe’s target.
3. If boiling water is above the target, rest it and measure; if it is at or below, brew straight off the boil.
4. Keep the temperature constant while you change one other variable, as on the ratio guide.