Celsius to Fahrenheit Converter

How to convert Celsius to Fahrenheit

The converter above is set to °C → °F. Type a temperature in Celsius and the Fahrenheit value appears as you type, with kelvin shown alongside.

1. Type the temperature in °C. Negative numbers and decimals work: −12.5 is fine.
2. Read the result in °F, with the formula used shown underneath.
3. Swap (⇄) to convert Fahrenheit back to Celsius.

Temperatures below absolute zero (−273.15 °C) are impossible, and the converter tells you so instead of showing a meaningless number.

The Celsius to Fahrenheit formula

°F = °C × 9 ⁄ 5 + 32 (9 ⁄ 5 is 1.8)

The two scales differ in two ways: a Fahrenheit degree is smaller (180 of them between freezing and boiling water, against 100 Celsius degrees), and the scales start at different points (water freezes at 0 °C but 32 °F). So you first scale by 1.8, then shift by 32.

Worked example: 25 °C × 1.8 = 45, and 45 + 32 = 77 °F.

The reverse: °C = (°F − 32) × 5 ⁄ 9. For 70 °F: 70 − 32 = 38, and 38 × 5 ⁄ 9 = 21.1 °C. The scales are defined in the international SI brochure (BIPM).

Celsius to Fahrenheit chart

A quick way to do it in your head

For weather, double the Celsius and add 30. 20 °C → 40 + 30 = 70 °F (exact: 68 °F). It’s within a few degrees between about 0 °C and 30 °C, close enough to decide on a coat. For anything that matters, such as cooking, medicine or science, use the exact formula or the converter.

Going the other way: subtract 30, then halve. 80 °F → 50 → 25 °C (exact: 26.7 °C).

A few pairs worth remembering: 10 °C ≈ 50 °F, 16 °C ≈ 61 °F, 28 °C ≈ 82 °F (the digits swap, a handy coincidence).

Oven temperatures

Recipes from the US give oven temperatures in °F; most others use °C. Common settings: 160 °C = 320 °F, 180 °C = 356 °F (recipes usually round to 350 °F), 200 °C = 392 °F (usually 400 °F), 220 °C = 428 °F (usually 425 °F). Many recipes also give a lower Celsius value for fan ovens; that’s a cooking adjustment, not part of the conversion. For cups, ounces and grams in the same recipe, the unit converter handles volume and weight too, and kg to lbs has its own page.

Body temperature and fever

37 °C equals exactly 98.6 °F, the traditional figure for normal body temperature, though healthy readings vary from person to person and through the day. A thermometer reading of 38 °C is 100.4 °F, a level often used to describe a fever. For health decisions, follow the advice of a doctor or your local health service rather than a converter.

Kelvin

Science uses kelvin (K), which starts at absolute zero: K = °C + 273.15. So 25 °C is 298.15 K and 77 °F. The converter shows all three at once, which is handy for physics and chemistry homework; for other calculations, the scientific calculator helps.

Who uses Fahrenheit?

Celsius is the everyday scale in almost every country. Fahrenheit is still used for weather, cooking and body temperature in the United States and a few other places, so you’ll meet it in American recipes, weather forecasts, travel plans, product manuals and medical leaflets. Scientists everywhere use Celsius and kelvin. When a source doesn’t say which scale it means, the size of the number is usually a clue: a “hot day” of 35 is Celsius, while 95 is Fahrenheit.

Ask in plain words

• “What is 180 °C in Fahrenheit?”
• “Convert 72 °F to Celsius.”
• “Is 38.5 °C a fever in Fahrenheit?”

Type it under the converter or in the AI workspace.