Fahrenheit to Celsius
Convert fahrenheit to celsius instantly — type a value and read the result, with the exact formula shown.
Example
0 °F = -17.77778 °C, 25 °F = -3.888889 °C, 100 °F = 37.77778 °C.
How it works
°C = (°F − 32) × 5/9. Every value is converted through a single kelvin base unit using internationally defined conversion factors, so any from/to pair stays consistent.
Good to know
Converting Fahrenheit to Celsius is one of the most common everyday calculations for anyone moving between the United States and the rest of the world. You will reach for it when reading a US weather forecast, following an American recipe that lists oven temperatures, interpreting a fever reading on an old thermometer, or making sense of pool, hot-tub, or thermostat settings written in °F while you think in °C.
The two scales come from different eras of thermometry. Fahrenheit, devised by Daniel Gabriel Fahrenheit in 1724, is the customary scale in the US and a few territories; it pegs water's freezing point at 32° and boiling at 212°, leaving 180 degrees between them. Celsius (originally "centigrade") is the metric-world standard used almost everywhere else and in all science, dividing that same span into a clean 100 degrees, from 0 °C freezing to 100 °C boiling.
A handy rule of thumb for fast mental math: subtract 30 from the Fahrenheit number, then halve it. So 70 °F is roughly (70 − 30) / 2 = 20 °C, close to the exact 21.1 °C. The proper formula is °C = (°F − 32) × 5/9. Two anchors worth memorizing are −40°, where both scales read the same, and 98.6 °F = 37 °C for normal body temperature.
The most common mistake is forgetting that these scales do not share a zero, so you cannot simply multiply by 5/9 — you must subtract 32 first. It also means a "10-degree change" is not equal on both scales: a 10 °F swing is only about 5.6 °C. Watch precision too, since 5/9 is a repeating decimal, so rounding a converted value too early (then converting back) can introduce small errors.
Frequently asked questions
How do you convert fahrenheit to celsius?
Use °C = (°F − 32) × 5/9. This tool applies that formula automatically as you type.
What is a quick reference for Fahrenheit to Celsius?
0 °F = -17.77778 °C; 25 °F = -3.888889 °C; 100 °F = 37.77778 °C.
Is this converter free and private?
Yes. It runs entirely in your browser, so your inputs never leave your device, there is no sign-up, and it works offline once loaded.
Are the conversions exact?
Conversions use internationally defined factors and are exact where the definitions are exact (for example, 1 inch = 2.54 cm). Displayed results are rounded for readability.
People also ask
What is 100°F in Celsius?
100 °F equals about 37.8 °C, using °C = (100 − 32) × 5/9. That is just above normal human body temperature, which is why 100 °F often signals a mild fever.
At what temperature are Fahrenheit and Celsius equal?
They are equal at −40°: −40 °F is exactly −40 °C. It is the only point where the two scales give the same number.
What is a normal body temperature in Celsius if it reads 98.6°F?
98.6 °F converts to 37 °C, the standard figure for normal human body temperature. A reading of 100.4 °F (38 °C) or higher is generally considered a fever.
How do I quickly estimate Fahrenheit to Celsius in my head?
Subtract 30 from the Fahrenheit value and divide by 2. For example, 80 °F gives roughly (80 − 30) / 2 = 25 °C, close to the exact 26.7 °C.
What is room temperature, 72°F, in Celsius?
72 °F is about 22.2 °C. Comfortable indoor room temperature usually falls between 68 and 72 °F, or roughly 20 to 22 °C.
Why do you subtract 32 before multiplying by 5/9?
Because the two scales have different zero points: water freezes at 32 °F but 0 °C. Subtracting 32 aligns the freezing point first, then 5/9 rescales the 180-degree Fahrenheit span to the 100-degree Celsius span.
What is 350°F in Celsius for baking?
A common 350 °F oven setting equals about 177 °C, often rounded to 175 °C or 180 °C on metric ovens. Recipes typically round to the nearest convenient dial mark.
What is 0°F in Celsius?
0 °F is about −17.8 °C, a genuinely cold winter temperature. The Fahrenheit zero was originally set near the coldest temperature Fahrenheit could reliably reproduce with a brine mixture.
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