Celsius to Fahrenheit calculator
Type a temperature in °C and get °F and Kelvin — with the formula written out and a chart of the temperatures people actually look up.
| Breakdown | Value |
|---|
Estimate. The method and sources are on this page — check them against your own case before you act.
How it is calculated
Celsius and Fahrenheit are two scales laid over the same physical temperature. They have different zero points and different step sizes, so the conversion is a multiply followed by an add — in that order.
°F = °C × 9/5 + 32 · °C = (°F − 32) × 5/9
Scale the step size
One Celsius degree is 1.8 Fahrenheit degrees, because the gap between freezing and boiling is 100 °C but 180 °F. Multiplying by 9/5 (or 1.8) matches the two step sizes.
Shift the zero
Water freezes at 0 °C but at 32 °F, so 32 is added after the scaling. That is why 0 °C = 32 °F and 100 °C = 212 °F, not 180 °F.
Check with an anchor
37 °C × 9/5 = 66.6, plus 32 gives 98.6 °F — body temperature. Using 2 instead of 1.8, or adding before multiplying, will miss that familiar figure.
Celsius to Fahrenheit — temperatures people look up
| Celsius (°C) | Fahrenheit (°F) | Kelvin (K) | What it is |
|---|---|---|---|
| -40 | -40 | 233.15 | Same reading on both scales |
| -20 | -4 | 253.15 | Deep freezer |
| -10 | 14 | 263.15 | Well below freezing |
| 0 | 32 | 273.15 | Water freezes |
| 10 | 50 | 283.15 | Cool day |
| 20 | 68 | 293.15 | Room temperature |
| 25 | 77 | 298.15 | Comfortable indoor |
| 30 | 86 | 303.15 | Hot day |
| 37 | 98.6 | 310.15 | Human body temperature |
| 40 | 104 | 313.15 | Very hot day |
| 50 | 122 | 323.15 | Extreme heat |
| 100 | 212 | 373.15 | Water boils at sea level |
| 180 | 356 | 453.15 | Oven, baking |
| 200 | 392 | 473.15 | Oven, roasting |
What most pages get wrong
One Celsius step is 1.8 Fahrenheit steps
A 5 °C change is a 9 °F change, because 100 Celsius degrees span the same range as 180 Fahrenheit degrees. Multiply by 9/5 to match the step sizes before adding the 32 offset.
−40 is the same on both scales
Set °F equal to °C in the formula and the only solution is −40. It is the one temperature you can read without converting, and a useful sanity check for any calculator.
37 °C is 98.6 °F
The familiar 98.6 °F comes from 37 × 1.8 + 32. A 38 °C reading is 100.4 °F — the arithmetic is exact, though what counts as a fever is a medical question, not a conversion one.
Indian forecasts use °C, American ones use °F
A 40 °C Indian summer day is 104 °F on a US weather app, and a 68 °F spring day is 20 °C. Kelvin is not used for weather because it starts at absolute zero.
Frequently asked questions
What is 37 °C in Fahrenheit?+
What is 100 °C in Fahrenheit?+
What is 40 °C in Fahrenheit?+
How do I convert Celsius to Fahrenheit by hand?+
Why is −40 °C equal to −40 °F?+
What is 180 °C in Fahrenheit for an oven?+
Why does the US use Fahrenheit instead of Celsius?+
Sources, dates and a changelog.
Every number this calculator uses is either an input you control or a value from the sources below. The formula is compiled and tested at build time, so the page cannot ship with a broken calculation.
Sources
This page
- Last verified: 29 October 2026
- Next review: 29 April 2027
- Vertical: Unit Converters
- Build tests: 4 passed
- Changelog: 1 entry
How we handle errors
- Spotted a mistake? Report it — we correct and log it.
- Corrections appear in the changelog below.
- Read the methodology and the disclaimer.