Temperature converter
Type a temperature and pick its scale. See it in Celsius, Fahrenheit and Kelvin at once, with the formula.
A temperature converter uses °F = °C × 9/5 + 32 and K = °C + 273.15. 37 °C, the figure often quoted for normal body heat, is 98.6 °F.
Degrees Celsius to degrees Fahrenheit
98.6 °F = 37 °C
| Degrees Celsius | 37 °C |
|---|---|
| Kelvin | 310.15 K |
Formula: °C = (°F − 32) × 5/9.
Exact formulas. Shown to 7 significant figures. Nothing you type is stored.
Checking a fever? See the chart below, then talk to a doctor if you are worried.
How to use this temperature converter
- Type the temperature you have, such as 98.6 or −5. Use a minus sign for below zero.
- Under From, pick its scale: °C, °F or K.
- Under To, pick the scale you want. The big number is your answer, and the card shows the formula used.
- Tap Swap units to convert the answer back.
Temperature conversion formulas
°F = °C × 9/5 + 32
°C = (°F − 32) × 5/9
K = °C + 273.15
- °C
- Degrees Celsius. Water freezes at 0 °C and boils at 100 °C at sea level.
- °F
- Degrees Fahrenheit. Water freezes at 32 °F and boils at 212 °F.
- K
- Kelvin, the science scale. It starts at absolute zero, so it has no negative values and no degree sign.
A change of 1 °C is the same as a change of 1.8 °F, and the same as 1 K. The scales do not start at the same zero, which is why you add or subtract as well as multiply.
Worked examples
- 37 °C to °F
- 37 × 9/5 + 32 = 98.6 °F
- −40 °C to °F
- −40 × 9/5 + 32 = −40 °F
- 300 K to °C
- 300 − 273.15 = 26.85 °C
So 98.6 °F, the figure often quoted for normal body heat, is 37 °C. And −40 is the one point where Celsius and Fahrenheit show the same number.
Body temperature (fever) chart in °C and °F
The NHS says a high temperature is usually 38 °C or above, and that this is sometimes called a fever. It also says normal body temperature is different for everyone and changes during the day. Source: NHS, high temperature (fever) in adults.
| Celsius | Fahrenheit | NHS guide |
|---|---|---|
| 36.0 °C | 96.8 °F | Below 38 °C |
| 36.5 °C | 97.7 °F | Below 38 °C |
| 37.0 °C | 98.6 °F | Below 38 °C |
| 37.5 °C | 99.5 °F | Below 38 °C |
| 38.0 °C | 100.4 °F | High temperature (fever) |
| 38.5 °C | 101.3 °F | High temperature (fever) |
| 39.0 °C | 102.2 °F | High temperature (fever) |
| 39.5 °C | 103.1 °F | High temperature (fever) |
| 40.0 °C | 104.0 °F | High temperature (fever) |
Readings vary with the thermometer and where you measure. This chart is for adults and is not medical advice. If a high temperature is not getting better or is getting worse, get medical help.
Common temperatures
| Celsius | Fahrenheit | Kelvin |
|---|---|---|
| −40 °C | −40 °F | 233.15 K |
| 0 °C | 32 °F | 273.15 K |
| 20 °C | 68 °F | 293.15 K |
| 25 °C | 77 °F | 298.15 K |
| 30 °C | 86 °F | 303.15 K |
| 37 °C | 98.6 °F | 310.15 K |
| 45 °C | 113 °F | 318.15 K |
| 100 °C | 212 °F | 373.15 K |
A quick mental check for weather: double the °C and add 30 to get a rough °F. It is close between 0 °C and 30 °C, but use the exact formula for anything that matters.
Where the formulas come from
- Kelvin and Celsius: K = °C + 273.15. Fahrenheit: °F = °C × 9/5 + 32. Source: NIST SP 811, chapter 4 and Appendix B.9.
- Fever threshold of 38 °C: NHS.
Temperature converter FAQs
What is 98.6 °F in Celsius?
37 °C. Subtract 32 from 98.6 to get 66.6, then multiply by 5/9.
What temperature is a fever?
The NHS says a high temperature is usually 38 °C (100.4 °F) or above. Normal temperature differs from person to person. This is not medical advice; talk to a doctor if you are worried.
What is the formula to convert Celsius to Fahrenheit?
Multiply by 9/5 (or 1.8), then add 32. To go back, subtract 32, then multiply by 5/9.
Where are Celsius and Fahrenheit equal?
At −40. −40 °C is exactly −40 °F.
Why does Kelvin have no negative numbers?
Kelvin starts at absolute zero, the coldest possible temperature, which is −273.15 °C. Nothing can be colder, so the converter warns you if you type a value below it.
Is my data saved?
No. Everything is worked out in your browser. Nothing you type is sent to us or stored. Your numbers go only into a link you choose to copy or share.
For general information only, not medical advice. Talk to a doctor about your health.