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Temperature Converter
Convert Celsius to Fahrenheit and back
Type a temperature into either box and read the other immediately. Celsius sits on the left, Fahrenheit on the right, and both stay visible so you can compare rather than convert one direction at a time. The copy button beside each value puts the converted figure on your clipboard.
Both readings come from one underlying temperature, so switching which side you type into never introduces rounding drift.
The Celsius to Fahrenheit formula
°F = (°C × 9 ÷ 5) + 32
Multiply by nine fifths — that is, by 1.8 — then add 32. Worked through with 20 °C: 20 × 1.8 = 36, and 36 + 32 = 68 °F.
The Fahrenheit to Celsius formula
°C = (°F − 32) × 5 ÷ 9
Subtract 32 first, then multiply by five ninths. Worked through with 98.6 °F: 98.6 − 32 = 66.6, and 66.6 × 5 ÷ 9 = 37 °C.
The order matters. Subtracting after multiplying, or adding 32 before scaling, gives the wrong answer — the offset has to be applied on the Fahrenheit side of the multiplication.
Why the conversion needs two steps
The two scales disagree about both the size of a degree and where zero sits. Water freezes at 0 °C but at 32 °F, and boils at 100 °C but at 212 °F. That is 100 Celsius degrees covering the same span as 180 Fahrenheit degrees, which is where the 9 ÷ 5 ratio comes from, while the 32 accounts for the different starting points.
A temperature difference is the exception: it converts by the multiplier alone. A rise of 5 °C is a rise of 9 °F, with no offset involved.
The two scales meet at exactly one point. At −40, Celsius and Fahrenheit read the same number.
Quick reference
| Celsius | Fahrenheit | Reference point |
|---|---|---|
| −40 °C | −40 °F | Where the scales meet |
| −17.8 °C | 0 °F | Zero Fahrenheit |
| 0 °C | 32 °F | Water freezes |
| 20 °C | 68 °F | Room temperature |
| 37 °C | 98.6 °F | Body temperature |
| 100 °C | 212 °F | Water boils at sea level |
| 180 °C | 356 °F | Moderate oven |
| 220 °C | 428 °F | Hot oven |
Where each scale is used
Celsius is the everyday scale nearly everywhere and the one used in science alongside Kelvin. Fahrenheit remains in general use in the United States and a few other places, which is why recipes, weather reports, and oven settings often need converting between the two.
If you also need Kelvin or Newton, or you are converting length, area, volume, or weight, the full Unit Converter covers all of them on one page.
Frequently asked questions
How do I convert Celsius to Fahrenheit?
Multiply the Celsius value by 9/5, then add 32. For example, 20 °C × 9/5 = 36, and 36 + 32 = 68 °F.
How do I convert Fahrenheit to Celsius?
Subtract 32 first, then multiply by 5/9. For example, 98.6 °F − 32 = 66.6, and 66.6 × 5/9 = 37 °C.
Why can't I just multiply by one number?
Celsius and Fahrenheit have different zero points as well as different degree sizes, so the conversion needs both a multiplier and an offset. Only a temperature difference converts by the multiplier alone: 1 °C of change equals 1.8 °F of change.
At what temperature are Celsius and Fahrenheit the same?
At −40. Both scales read −40 at that point, which is the single temperature where the two lines cross.
What is normal body temperature in Celsius and Fahrenheit?
The traditional figure is 37 °C, or 98.6 °F. Healthy readings vary by person, by time of day, and by where the measurement is taken, so treat it as a reference point rather than a fixed value.
Do I need Kelvin or Newton as well?
This page keeps to the two scales in everyday use. The full Unit Converter adds Kelvin and Newton alongside length, area, volume, and weight.