Europe reports a heatwave at 38 degrees; an American hears a mild spring day. This converter settles the world's most argued-over unit gap, translating Celsius into Fahrenheit with the exact formula — for weather on holiday, ovens following foreign recipes, fever readings, and every other moment the two everyday scales collide.
Quick Answer
Multiply by 9/5, then add 32: °F = °C × 9/5 + 32. A pleasant 23 °C becomes 23 × 1.8 + 32 = 73.4 °F. The two adjustments have distinct jobs: 9/5 rescales the degree size, and 32 shifts for the different zero point.
Why This Conversion Has Two Steps
Between water freezing and boiling, Celsius counts 100 degrees and Fahrenheit counts 180. A Fahrenheit degree is therefore smaller — five-ninths the size of a Celsius degree — and any span measured in Celsius must grow by the ratio 180/100, which is 9/5, to be expressed in Fahrenheit. That is step one, and it is about size only.
Step two exists because the scales start counting in different places. Celsius puts freezing water at 0; Fahrenheit puts it at 32. Even a temperature of absolute agreement in span would sit 32 Fahrenheit degrees higher on the page simply because the ruler starts earlier. Add the 32 and the two corrections together reproduce Fahrenheit exactly, for every value, in both directions (subtract 32, then multiply by 5/9, to come back).
One elegant consequence: the scales cross. Set °C × 9/5 + 32 equal to the same number in Celsius and the solution is −40, the only temperature that reads identically on both — a trivia answer, but also a genuine checkpoint on the coldest days of a North American winter, when broadcasters stop bothering to specify which scale they mean.
How to Use the Celsius to Fahrenheit Converter
- Enter the Celsius value as a number; negative values are welcome and common for winter weather.
- Read the Fahrenheit result, computed with the exact 9/5 factor rather than the "double and add 30" shortcut.
- For oven settings, convert the recipe's Celsius figure and then allow for your oven type — fan ovens typically run about 20 °C (36 °F) cooler than the conventional setting for the same result.
- For body temperature, keep one decimal place: the difference between 37.0 °C (98.6 °F) and 38.0 °C (100.4 °F) is the difference between normal and a fever, and whole-number rounding erases it.
- Converting a range — "bake at 180–200 °C" — means converting both ends separately (356–392 °F), not converting the width of the range.
- Verify an important figure by converting it back with the reverse tool linked below; landing on your starting number confirms the arithmetic.
Worked Example: A Fever and a Forecast
A European thermometer reads 38.5 °C for a sick child, and a grandparent in Ohio asks what that is in Fahrenheit. Multiply first: 38.5 × 9/5 = 38.5 × 1.8 = 69.3. Then shift: 69.3 + 32 = 101.3 °F — unmistakably a fever in either system (normal body temperature, 37 °C, is the famous 98.6 °F, and 38 °C is 100.4 °F). The forecast landmarks that help you read foreign weather at a glance:
- −10 °C = 14 °F (bitter cold)
- 0 °C = 32 °F (freezing point)
- 10 °C = 50 °F (a cool day)
- 20 °C = 68 °F (room temperature)
- 30 °C = 86 °F (a hot day)
- 40 °C = 104 °F (dangerous heat)
Notice the rhythm in the middle of the table — every 10 °C step is an 18 °F step — which is the fastest reliable way to estimate in your head before confirming here.
Shortcuts and Slips to Watch For
The folk rule "double it and add 30" survives because it works passably for weather: at 20 °C it yields 70 against the true 68. But its error grows away from mild temperatures — at 0 °C it overshoots by 2, at 40 °C it says 110 against the true 104 — and it has no business near ovens, aquariums, incubators or medicine. This converter never uses it, and the shortcut has no place near an aquarium heater, an incubator or a sick child's temperature, which is why every figure on this page comes from the exact formula. The reverse folk error is applying the steps in the wrong order coming back (multiplying before subtracting the 32), which silently mangles every value; the order is subtract, then scale.
Gas marks deserve a warning of their own: British recipes may give "Gas Mark 4" instead of a temperature, and that is neither Celsius nor Fahrenheit — Gas Mark 4 corresponds to 180 °C / 356 °F, so convert from the Celsius equivalent rather than treating the mark as a temperature. Finally, beware weather apps that mix scales within one screen — a phone set to Fahrenheit showing a European data source has confused many travellers, and the size check is your friend: a July afternoon quoted as 95 is Fahrenheit, as 35 is Celsius, and the two describe the same hot day.
Ovens are where this conversion earns its keep daily, so the settings cooks actually use are worth gathering in one place. A slow oven at 150 °C is 302 °F; a moderate 170 °C is 338 °F; the all-purpose 180 °C is 356 °F; a hot 200 °C pizza-and-roast setting is 392 °F; and a fierce 220 °C is 428 °F, with 240 °C reaching 464 °F for flatbreads and searing. Each value follows from the same two steps — × 9/5, then + 32 — and listing them exposes the pattern that every extra 10 °C adds exactly 18 °F, a rhythm that makes spot-checking any recipe conversion quick: if the Fahrenheit figure for a hotter setting has not grown by roughly 18 per 10 degrees, a step has been skipped.
The Rest of the Temperature Family
Working in reverse, the Fahrenheit to Celsius converter handles American figures you need in metric, while the Temperature Conversion hub covers all three scales including Kelvin for scientific values. All of the site's unit tools are indexed in the converters section.