-21 Fahrenheit to Celsius
-21 °F ≈ -29.44 °C
-21 degrees Fahrenheit is approximately -29.44 degrees Celsius.
How to convert -21 °F to °C
Use the formula °C = (°F − 32) × 5/9:
°C = (-21 − 32) × 5/9°C = -53 × 5/9°C = -29.444444
So -21 °F = -29.444444 °C, or about -29.44 °C rounded.
Rounded values and quick estimate
- Rounded to a whole number: -29 °C
- Rounded to one decimal place: -29.4 °C
Quick mental estimate: subtract 30 and halve it. For -21 °F that gives about -25.5 °C — off by 3.94 °C (13.4%). Use the exact formula when precision matters.
-21 Fahrenheit in other units
-29.44 °C is very cold weather, well below the freezing point of water. It is typical of a hard winter in northern climates; warm layers, gloves and a hat are essential outdoors.
- Celsius
- -29.44 °C
- Degrees Réaumur
- -23.56 °Ré
- Degrees Delisle
- 194.17 °De
- Degrees Newton
- -9.72 °N
- Degrees Rømer
- -7.96 °Rø
- Kelvin
- 243.71 K
- Rankine
- 438.67 °R
-21 °F and nearby values
About fahrenheit and celsius
The Fahrenheit scale puts water’s freezing point at 32 °F and boiling point at 212 °F. It is the everyday temperature scale in the United States.
The Celsius scale sets the freezing point of water at 0 °C and its boiling point at 100 °C (at sea level). It is used for everyday temperatures in almost every country.
Related conversions
Frequently asked questions
What is -21 Fahrenheit in Celsius?
-21 degrees Fahrenheit is about -29.44 degrees Celsius (-21 °F ≈ -29.44 °C).
How do you convert -21 °F to °C?
Apply °C = (°F − 32) × 5/9: °C = (-21 − 32) × 5/9, °C = -53 × 5/9, °C = -29.444444.
How many degrees Fahrenheit is -29.44 °C?
-29.44 °C is about -20.99 degrees Fahrenheit.