How to convert celsius to fahrenheit
Temperature is the one conversion family with an offset as well as a ratio: the degree sizes differ by 9/5 and the zeros sit 32 degrees apart, so both steps are needed, in that order. The anchors check out exactly — 0 °C is 32 °F, 100 °C is 212 °F, and −40 is the same on both scales.
The Celsius scale sets 0 at water's freezing point and 100 at its boiling point (at sea level), dividing the span into a hundred degrees. Fahrenheit divides the same span into 180 degrees, with freezing at 32 and boiling at 212 — which is why the conversion is the only one in this section with both a multiplication (9/5, the ratio of the degree sizes) and an addition (32, the gap between the zeros). Both scales are defined exactly, so the formula is exact too.
Weather is the everyday job: 20 °C is a mild 68 °F, 30 °C a hot 86 °F, and the table's 37 is body temperature, 98.6 °F. This page's default, 100 °C, is boiling water at 212 °F. Cooking crosses constantly — a 180 °C oven is 356 °F, conventionally set to 350 °F in American recipes — and the famous −40 in the table is the crossover: the one temperature that reads identically on both scales, and the surest check that a converter has its formula right.
The common mistake is forgetting the +32, or adding it before multiplying: 20 °C wrongly worked gives 36 or 93.6 instead of 68 °F. The mental shortcut “double it and add 30” is serviceable for weather (it gives 70 for 20 °C) but drifts at the extremes — at 100 °C it claims 230 against the true 212. Use the shortcut to decide on a jacket; use this page's exact formula for ovens, science, medicine and anything with a threshold.
Worked example
100 degrees Celsius is 212 degrees Fahrenheit: 100 × 9/5 + 32 = 212 — the boiling point of water at sea level, the anchor at the top of both scales.
How to use this converter
- Enter your value in celsius in the box above — the result updates as you type.
- Read the converted value in fahrenheit in the headline panel.
- Check the factor, the formula and the inverse result (your answer converted back) in the stats if you need to show your working.
- Use the Celsius to Fahrenheit conversion table below for other common values without typing each one.