🌡️ Celsius to Fahrenheit Converter
Convert degree Celsiuss to degree Fahrenheits and back. The exact factor, a table of the values people look up most, and what each unit is actually used for.
Converting degree Celsiuss to degree Fahrenheits
Degree Celsiuss and degree Fahrenheits do not share a zero point, so the conversion is a formula rather than a factor.
°F = °C × 9/5 + 32 · °C = (°F − 32) × 5/9
Getting the precision right
This is the one common conversion that is not a simple multiplication, because the two scales have different zero points as well as different degree sizes. Multiply by 9/5 and add 32; forgetting the offset is the classic error. The scales cross at −40°, which is the same temperature in both.
Where each unit is used
Celsius is used for weather and cooking nearly everywhere. Fahrenheit survives for everyday temperature in the United States and a few territories, and informally in the United Kingdom for hot summer days, where tabloid headlines still reach for the bigger number.
Values worth knowing
| °C | °F |
|---|---|
| -40 | -40 |
| -10 | 14 |
| 0 | 32 |
| 10 | 50 |
| 20 | 68 |
| 25 | 77 |
| 30 | 86 |
| 37 | 98.6 |
| 40 | 104 |
| 100 | 212 |
0°C is 32°F, water freezing. 37°C is 98.6°F, body temperature. 100°C is 212°F, water boiling at sea level. 20°C is 68°F, a comfortable room.
Where the two units came from
Fahrenheit set his zero at the coldest temperature he could reliably reproduce, a brine of ice and salt, and originally put body temperature at 96 because it divided neatly by twelve. Celsius proposed his scale in 1742 with 0 for boiling and 100 for freezing — inverted from what we use now — and it was turned the right way up after his death. The modern definitions are both tied to the kelvin, so neither scale depends on water any more.
Round the result to the precision your own work needs. These converters carry the full factor, which is useful for checking but rarely what you want to write down.
Once you have this figure, the liters to gallons is where it usually goes next. the ml to oz is the related one people reach for afterwards.
Frequently Asked Questions (FAQs)
What is the formula for Celsius to Fahrenheit?
Multiply by 9, divide by 5, then add 32. Going the other way, subtract 32 first and then multiply by 5/9. The order matters: the offset must be removed before scaling, not after.
Is there a quick mental method?
Double the Celsius figure and add 30. For 20°C that gives 70°F against a true 68°F, which is close enough for weather. The shortcut drifts at extremes, overestimating by about 6 degrees at 40°C.
At what temperature are Celsius and Fahrenheit equal?
At −40 degrees. The two scales converge there because of the different degree size and offset, which is why “minus forty” needs no unit.
Why does the US use Fahrenheit?
It adopted the scale early and never completed metrication. Fahrenheit's supporters argue its degrees are finer for describing weather without decimals, since the 0 to 100 range covers roughly the span of habitable outdoor temperatures.