21 Fahrenheit to Celsius
21 °F ≈ -6.11 °C
21 degrees Fahrenheit is approximately -6.11 degrees Celsius.
How to convert 21 °F to °C
Use the formula °C = (°F − 32) × 5/9:
°C = (21 − 32) × 5/9°C = -11 × 5/9°C = -6.111111
So 21 °F = -6.111111 °C, or about -6.11 °C rounded.
Rounded values and quick estimate
- Rounded to a whole number: -6 °C
- Rounded to one decimal place: -6.1 °C
Quick mental estimate: subtract 30 and halve it. For 21 °F that gives about -4.5 °C — off by 1.61 °C (26.4%). Use the exact formula when precision matters.
21 Fahrenheit in other units
-6.11 °C is below the freezing point of water (0 °C / 32 °F), so expect ice and frost. In weather terms it is a cold winter day.
- Celsius
- -6.11 °C
- Degrees Réaumur
- -4.89 °Ré
- Degrees Delisle
- 159.17 °De
- Degrees Newton
- -2.02 °N
- Degrees Rømer
- 4.29 °Rø
- Kelvin
- 267.04 K
- Rankine
- 480.67 °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 -6.11 degrees Celsius (21 °F ≈ -6.11 °C).
How do you convert 21 °F to °C?
Apply °C = (°F − 32) × 5/9: °C = (21 − 32) × 5/9, °C = -11 × 5/9, °C = -6.111111.
How many degrees Fahrenheit is -6.11 °C?
-6.11 °C is about 21 degrees Fahrenheit.