CALCSLIP

Temperature converter

Celsius, Fahrenheit and Kelvin, with the formula for each direction.

°C

Result

21 °C =
69.8 °F
Kelvin
294.15 K

How this was calculated

  1. Conversion

    °F = °C × 9/5 + 32

    21 °C = 69.8 °F

The formulas

°F = °C × 9/5 + 32 °C = (°F − 32) × 5/9 K = °C + 273.15

Water freezes at 0 °C (32 °F, 273.15 K) and boils at 100 °C (212 °F) at sea level. −40 is the same in Celsius and Fahrenheit. Nothing can be colder than absolute zero, 0 K or −273.15 °C, so the converter rejects anything below it.

Questions people ask

Is there a quick way to convert in my head?

Double the Celsius figure and add 30 for a rough Fahrenheit value: 20 °C ≈ 70 °F (exactly 68 °F).

What is normal body temperature?

About 37 °C, or 98.6 °F, though it varies through the day and from person to person.