Celsius to Fahrenheit converter
This Celsius to Fahrenheit converter multiplies degrees Celsius by 9/5 and adds 32. It opens on 20 °C, which is 68 °F, and it rejects any value below absolute zero, -273.15 °C. The chart below lists common readings, and the conversion runs in your browser.
Your result
Results use the displayed unit definitions. Copy copies the value; Download includes units, definitions and rounding notes.
Celsius to Fahrenheit chart
Every Fahrenheit value in this chart is what the converter returns for that Celsius reading at 10 significant digits, because the chart was built with the converter's own code. A step of one Celsius degree moves the Fahrenheit reading by 1.8 degrees, which is why 18 °C, 21 °C and 22 °C land on decimals.
| Celsius (°C) | Fahrenheit (°F) |
|---|---|
| -40 | -40 |
| -20 | -4 |
| -18 | -0.4 |
| -10 | 14 |
| 0 | 32 |
| 5 | 41 |
| 10 | 50 |
| 15 | 59 |
| 18 | 64.4 |
| 20 | 68 |
| 21 | 69.8 |
| 22 | 71.6 |
| 25 | 77 |
| 30 | 86 |
| 35 | 95 |
| 37 | 98.6 |
| 38 | 100.4 |
| 40 | 104 |
| 50 | 122 |
| 100 | 212 |
| 180 | 356 |
| 200 | 392 |
Type readings below zero with the minus sign too, as -18. The chart stops at 200 °C, but the converter has no upper limit below the browser's number range.
Celsius to Fahrenheit formula
The Fahrenheit reading is the Celsius reading times 9/5, plus 32. The 9/5 comes from the size of the degrees: from 0 °C to 100 °C the Fahrenheit reading climbs from 32 °F to 212 °F, so 100 Celsius degrees span 180 Fahrenheit degrees. The 32 is the offset, the Fahrenheit reading at 0 °C. In decimals, 9/5 is 1.8, so the same rule reads °F = °C × 1.8 + 32.
- Celsius to Fahrenheit °F = °C × 9/5 + 32 Example: 37 °C = 98.6 °F.
- Fahrenheit to Celsius °C = (°F − 32) × 5/9 Example: 100 °F = 37.77777778 °C.
Four known points help with checks. -40 °C equals -40 °F, 0 °C is 32 °F, 37 °C is 98.6 °F and 100 °C is 212 °F. The swap button (⇄) turns this page into the second formula, and the converter subtracts before it scales, so 32 °F comes back as exactly 0 °C.
How to convert Celsius to Fahrenheit here
The converter opens on Temperature, with Celsius (°C) in From, Fahrenheit (°F) in To and 20 in Value or size. Select Convert to see 68 °F, or change the reading first.
- Type the Celsius reading in Value or size. Use a dot for decimals, as in 37.5, and a leading minus for cold readings, as in -18.
- Keep Celsius (°C) and Fahrenheit (°F), or choose Kelvin (K) or Rankine (°R). The swap button (⇄) gives Fahrenheit to Celsius.
- Leave Display precision at 10 significant digits, or pick 6 or 15 for fewer or more digits.
- Select Convert or press Enter. The line under Converted value reads, for example, 20 Celsius (°C) = 68 Fahrenheit (°F).
- Copy result copies the number, and Download text saves unit-conversion.txt with that line and the notes. Reset returns to 20 °C in Fahrenheit, even after you swap the units.
Limits
The converter reads every value as a temperature on a thermometer, not a change in temperature. A rise of 10 Celsius degrees is a rise of 18 Fahrenheit degrees, but typing 10 here gives 50 °F, the reading. For a change, multiply by 1.8 and skip the 32.
Readings below absolute zero, -273.15 °C, return an error, so -274 °C is refused while -273.15 °C gives -459.67 °F. Results are decimals, and a reading such as 100 °F shows as 37.77777778 °C at 10 significant digits. The page converts one reading at a time, and a comma in the field returns an error. So does a unit letter, as in 20C; type the number alone.
Kelvin and Rankine are in the same menus. 20 °C is 293.15 K, and absolute zero, -273.15 °C, is 0 K.
Questions
How do I convert C to F easily?
Multiply the Celsius reading by 1.8 and add 32. For 25 °C, 25 × 1.8 is 45, and 45 + 32 gives 77 °F. For a rough figure in your head, double the reading and add 30. That shortcut is exact at 10 °C but gives 104 °F for 37 °C, where the true value is 98.6 °F.
Is 100 Fahrenheit 40 Celsius?
Not quite. 100 °F is 37.77777778 °C at 10 significant digits, and 40 °C is 104 °F. To check, select the swap button, type 100 and select Convert. The two scales give the same number only at -40, where -40 °C and -40 °F are the same temperature.
What temperature is 20 C in Fahrenheit?
20 °C is 68 °F, because 20 × 9/5 is 36 and 36 + 32 is 68. It is the value this page opens with, so selecting Convert right away shows it. Nearby readings from the chart are 18 °C at 64.4 °F, 22 °C at 71.6 °F and 25 °C at 77 °F.
What is 37.5 C converted to Fahrenheit?
37.5 °C is 99.5 °F: 37.5 × 1.8 is 67.5, and adding 32 gives 99.5. For comparison, 37 °C is 98.6 °F and 38 °C is 100.4 °F, so each half degree Celsius adds 0.9 °F. Type 37.5 with a dot, because the field reads a comma as an error.
What is 50 below Celsius in Fahrenheit?
Fifty below zero Celsius, -50 °C, is -58 °F. Type it with a leading minus sign, as -50, and keep Celsius (°C) in From. Below -40 the Fahrenheit number is the lower of the two, and above -40 it is the higher. The converter accepts any reading down to -273.15 °C.