Celsius to Fahrenheit Converter
Type a temperature in °C and see °F instantly. Free, no sign-up, runs in your browser.
Need the opposite? Fahrenheit to Celsius
This Celsius to Fahrenheit converter applies the exact formula the moment you type: °F = °C × 9/5 + 32. Unlike length or weight, temperature is not a simple multiplication — the +32 offset is why 0°C is not 0°F but 32°F, the freezing point of water.
Three situations send most people here. Fever: 38°C is 100.4°F, the threshold US guidance uses for a fever, and 40°C is a worrying 104°F. Weather: a pleasant 25°C day is 77°F, while a 35°C heatwave is 95°F. Ovens: a recipe's moderate 180°C is 356°F, which US cookbooks round to 350°F.
The conversion happens entirely in your browser — instant, free, and private, with no limit on how many temperatures you check.
How to convert Celsius to Fahrenheit
- Enter the temperature in °C — negatives like -10 work too.
- Read the °F result instantly; it updates as you type.
- Slide the value up or down to explore a range, like an oven dial.
- Use the swap control for Fahrenheit to Celsius.
- Copy the result with one click.
Anchor points worth memorising
A handful of pairs cover most of life: 0°C = 32°F (freezing), 10°C = 50°F (jacket weather), 20°C = 68°F (room temperature), 30°C = 86°F (hot day), 37°C = 98.6°F (body temperature), 100°C = 212°F (boiling water). The scales cross at one strange point: -40°C equals -40°F exactly.
For cooking, the common oven settings map as: 160°C = 320°F, 180°C = 356°F (≈350°F), 200°C = 392°F (≈400°F), 220°C = 428°F (≈425°F). If you use a fan oven, remember the usual advice to drop about 20°C before converting.
The formula and why the offset exists
The exact formula is °F = °C × 9/5 + 32, which is the same as °C × 1.8 + 32. Two things happen at once: the ×9/5 rescales the degree size, because a Celsius degree is 1.8 times bigger than a Fahrenheit degree, and the +32 shifts the zero point, since water freezes at 0°C but at 32°F.
That offset is what makes temperature different from length or weight — you cannot simply multiply. Forgetting the +32, or adding it before you multiply, are the two ways this goes wrong. Always multiply first, then add 32.
A worked example, step by step
Convert 25°C. Multiply by 1.8: 25 × 1.8 = 45. Add 32: 45 + 32 = 77°F. So a mild 25°C day is 77°F.
The order matters. For 37°C: 37 × 1.8 = 66.6, plus 32 = 98.6°F — body temperature. Had you added 32 first (37 + 32 = 69, then ×1.8 = 124.2) you would get nonsense, which is exactly why the multiply-then-add order is worth drilling in.
A reference set from cold to hot
In prose: −10°C = 14°F, 0°C = 32°F, 10°C = 50°F, 20°C = 68°F, 25°C = 77°F, 30°C = 86°F and 40°C = 104°F. Each 10°C step adds 18°F, so the gaps are perfectly even.
For the body and the kitchen: 37°C = 98.6°F (normal), 38°C = 100.4°F (fever threshold), 100°C = 212°F (boiling water), 180°C = 356°F (a moderate oven) and 220°C = 428°F (a hot oven).
Where each scale is used
Celsius is the everyday scale almost everywhere and the standard for science worldwide. Fahrenheit remains in daily use mainly in the United States and a few territories for weather, cooking and body temperature, so Celsius to Fahrenheit is the direction you need when handing a number to an American audience.
Even in the US, Celsius shows up in science, medicine and increasingly on phones, so the two scales coexist. Knowing this conversion lets you read a European recipe or forecast and restate it comfortably for a US reader.
Precision and rounding
The formula is exact, so rounding is only for readability. For weather, whole degrees are fine — say 77°F, not 77.0. For a fever or a lab reading, keep the decimal, because 0.4°F is the whole difference between a flat 100°F and the 100.4°F fever line.
A quirk of the offset: temperature differences don't carry the +32. A rise of 5°C is a rise of 9°F (5 × 1.8), not 5°C plus 32. Use the full formula for a temperature, but only the ×1.8 part for a change in temperature.
Common mistakes and the reverse conversion
Besides the order-of-operations trap, the other slip is using the wrong direction's formula. Celsius to Fahrenheit multiplies then adds; if you catch yourself subtracting 32, you are actually doing Fahrenheit to Celsius. A quick sanity check: above −40°, the Fahrenheit number is always the larger of the two.
To reverse it, undo the steps in the opposite order: °C = (°F − 32) × 5/9. Subtract 32 first, then multiply by 5/9. So 77°F − 32 = 45, × 5/9 = 25°C — right back where we started.
Frequently asked questions
What is the exact Celsius to Fahrenheit formula?
Multiply by 9, divide by 5, then add 32 — or equivalently multiply by 1.8 and add 32. So 38°C × 1.8 = 68.4, plus 32 gives 100.4°F.
Is there a quick trick for doing it in my head?
Double the Celsius figure and add 30. For 20°C that gives 70°F (true answer 68°F). It is spot-on at 10°C and drifts a few degrees off at extremes — fine for weather, not for medicine.
What is 38°C in Fahrenheit — is that a fever?
38°C is exactly 100.4°F, and yes, that is the standard fever threshold in both systems. Normal body temperature of 37°C is 98.6°F.
What is 180°C for baking?
180°C is 356°F. American recipes call the same moderate oven 350°F, so 180°C and 350°F are interchangeable in practice.
Why do Celsius and Fahrenheit meet at -40?
Because of the offset in the formula. Solve C = 1.8C + 32 and you get C = -40, so -40° is the single temperature that reads the same on both scales.
Is this converter free and private?
Yes. It is free, needs no account, and the arithmetic runs on your device — nothing you type is sent to a server.