Body temperature, 37 °C in °F
- Value
- 37 °C
- From
- degree Celsius (°C)
- To
- degree Fahrenheit (°F)
- Converted value
- 98.6 °F
- Conversion
- 37 °C = 98.6 °F
- Exactness
- Exact
Checked against: °F = °C × 9/5 + 32 (NIST SP 811 §4.2.1.1): 37 × 1.8 + 32 = 98.6
Temperature converter
Convert Celsius to Fahrenheit, °F to °C and both to kelvin with °F = °C × 9/5 + 32. Includes Rankine and Réaumur; rejects values below absolute zero.
By AdminDrafted with AI writing toolsUpdated Checked examples: 5
Converted value
°F
Converted value: 98.6 °F
- Conversion
- 37 °C = 98.6 °F
- Exactness
- Exact
37 °C is exactly 98.6 °F.
On a thermometer
37 °C in every Temperature unit
| Unit | Value | Definition |
|---|---|---|
| kelvin (K) | 310.15 | Base unit |
| degree Celsius (°C) | 37 | K = °C + 273.15, exact |
| degree Fahrenheit (°F) | 98.6 | K = (°F + 459.67) × 5/9, exact |
| degree Rankine (°R) | 558.27 | 1 °R = 5/9 K, exact |
| degree Réaumur (°Ré) | 29.6 | K = (°Ré + 218.52) × 5/4, exact |
How it's calculated S
Convert degree Celsius to kelvin
K = °C + 273.15, exact
Convert kelvin to degree Fahrenheit
K = (°F + 459.67) × 5/9, exact
An offset as well as a factor
Temperature scales can have different zero points, so converting full readings may require an offset as well as scaling. Celsius and Réaumur share a zero point. A temperature difference of 1 °C corresponds to 1.8 °F using only the scale factor; displayed decimals are rounded where needed.
Both units are defined exactly and the converted mathematical value has a terminating decimal. A displayed result may still be rounded.
About the temperature converter
Temperature scales differ in the size of a degree and in where zero sits, so a conversion adds an offset as well as multiplying: °F = °C × 9/5 + 32, and K = °C + 273.15. The converter works through kelvin, whose zero is absolute zero, and rejects any value below it (−273.15 °C or −459.67 °F).
The default is a reference calculation: 37 × 9/5 + 32 = 98.6 °F. Weather forecasts and oven settings are everyday uses. NHS adult guidance usually considers 38 °C or above a high temperature, corresponding to 100.4 °F.
A temperature difference converts without the offset: a rise of 10 °C is a rise of 18 °F. Rankine is the absolute scale with Fahrenheit-sized degrees, and Réaumur is a historical scale with 80 degrees between the freezing and boiling points of water.
How to convert Celsius to Fahrenheit
Multiply the Celsius reading by 1.8 (9/5) and add 32: °F = °C × 1.8 + 32. As a reference conversion, 37 °C is 98.6 °F: 37 × 1.8 = 66.6, and 66.6 + 32 = 98.6. Use it for any thermometer reading, from weather to ovens; a temperature change skips the +32.
The scales differ in both zero point and degree size. Water freezes at 0 °C or 32 °F and boils at 100 °C or 212 °F at standard atmospheric pressure, so 100 Celsius degrees span 180 Fahrenheit degrees: each Celsius degree is 1.8 Fahrenheit degrees.
For a quick estimate, double the Celsius figure and add 30. That is exact at 10 °C (50 °F), gives 70 instead of 68 at 20 °C, and 90 instead of 86 at 30 °C.
Decimal approximations in the prose below are rounded. The conversion formulas themselves are exact.
How to convert Fahrenheit to Celsius
Subtract 32 first, then multiply by 5/9 (or divide by 1.8): °C = (°F − 32) × 5/9. So 100 °F is 68 × 5/9 ≈ 37.78 °C, and a 350 °F oven is 176.67 °C, which many recipes round to 180 °C.
Below 32 °F the Celsius value turns negative: 0 °F is −17.78 °C. Both relations are exact definitions listed in NIST SP 811, Appendix B.9.
Common temperatures in Celsius and Fahrenheit
- −40 °C = −40 °F, the one reading where the two scales agree
- 0 °C = 32 °F, the freezing point of water
- 20 °C = 68 °F, a typical room temperature
- 37 °C = 98.6 °F, a reference temperature conversion
- 38 °C = 100.4 °F, a high temperature usually considered in NHS guidance for adults
- 100 °C = 212 °F, the boiling point of water at standard atmospheric pressure
- 180 °C = 356 °F, a moderate oven
Kelvin, Rankine and Réaumur
Kelvin uses Celsius-sized degrees but counts from absolute zero: K = °C + 273.15, so 25 °C is 298.15 K. It is written without a degree sign. Rankine does the same for Fahrenheit: °R = °F + 459.67, which also equals K × 1.8.
Réaumur, a historical scale, puts 80 degrees between the freezing and boiling points of water, so °Ré = °C × 0.8. That is why 80 °Ré is 100 °C.
Absolute zero is 0 K, −273.15 °C, −459.67 °F, 0 °R or −218.52 °Ré. This converter handles ordinary thermodynamic temperature readings and requires values at or above absolute zero.
Temperature conversion chart
Long decimals are rounded to six places.
| Value | From | To | Converted reading |
|---|---|---|---|
| 37 | °C | °F | 98.6 |
| -40 | °C | °F | -40 |
| 0 | K | °C | -273.15 |
| 100 | °F | °C | 37.777778 |
| 300 | K | °R | 540 |
| 80 | °Ré | °C | 100 |
Converting a temperature change
A change has no zero point to shift, so only the degree size counts: Δ°F = Δ°C × 1.8. A day that warms by 10 °C warms by 18 °F. The readings agree: 20 °C is 68 °F and 30 °C is 86 °F, which are 18 °F apart.
A change of 1 K equals a change of 1 °C, and a change of 1 °R equals a change of 1 °F.
Common mistakes
- Multiplying before subtracting 32. 100 × 5/9 − 32 gives 23.56, but 100 °F is 37.78 °C.
- Adding 32 to a difference. A 5 °C rise is a 9 °F rise, while a 5 °C reading is 41 °F.
- Dropping the .15. 25 °C is 298.15 K; using 273 puts every kelvin answer 0.15 K low.
- Reading ratios on a scale with an arbitrary zero. 20 °C is not twice as warm as 10 °C: in kelvins they are 293.15 K and 283.15 K, about 3.5% apart.
- Writing °K. The kelvin takes no degree sign, so write 300 K.
Related temperature converters
For a single direction, use Celsius to Fahrenheit, Fahrenheit to Celsius, Celsius to Kelvin or Kelvin to Fahrenheit. Recipe settings, including fan ovens and gas marks, have their own oven temperature converter.
Worked examples
−40 is the same in both scales
- Value
- -40 °C
- From
- degree Celsius (°C)
- To
- degree Fahrenheit (°F)
- Converted value
- -40 °F
Checked against: −40 × 9/5 + 32 = −40
Absolute zero in °F
- Value
- 0 K
- From
- kelvin (K)
- To
- degree Fahrenheit (°F)
- Converted value
- -459.67 °F
- Exactness
- Exact
Checked against: 0 K = −273.15 °C; −273.15 × 9/5 + 32 = −459.67 °F (NIST SP 811 App. B.9)
100 °F in °C
- Value
- 100 °F
- From
- degree Fahrenheit (°F)
- To
- degree Celsius (°C)
- Converted value
- 37.7777777778 °C
- Exactness
- Exact definitions, repeating decimal
Checked against: (100 − 32) × 5/9 = 340/9
Questions
How do I convert Celsius to Fahrenheit?
Multiply by 9/5 (1.8) and add 32. For 37 °C, 37 × 1.8 = 66.6, and adding 32 gives 98.6 °F. To go back, subtract 32 and multiply by 5/9: (100 °F − 32) × 5/9 ≈ 37.78 °C. NIST SP 811 states the same relation as t/°F = 1.8 t/°C + 32.
Is 98.6 °F normal body temperature?
98.6 °F is the exact Fahrenheit value of 37 °C. Normal body temperature varies between people and during the day. NHS guidance for adults usually considers 38 °C or above a high temperature; 38 °C converts exactly to 100.4 °F.
At what temperature are Celsius and Fahrenheit equal?
At −40. Setting the two numbers equal in °F = °C × 9/5 + 32 gives x = 1.8x + 32, so x = −40, and −40 °C is exactly −40 °F. It is the only crossing point because the degrees differ in size; above −40 the Fahrenheit number is always the larger one.
How do I convert Celsius to kelvin?
Add 273.15: 25 °C is 298.15 K, and absolute zero, 0 K, is −273.15 °C. A kelvin is the same size as a Celsius degree and, since 2019, is defined by fixing the Boltzmann constant at 1.380649 × 10⁻²³ J/K (BIPM SI Brochure). Kelvin is written without a degree sign.
Why is a 10 °C rise an 18 °F rise and not 50 °F?
Because a difference has no zero point to shift. One Celsius degree is 1.8 Fahrenheit degrees, so a change of 10 °C is a change of 18 °F; the +32 applies only to a reading on the scale. The converter's steps show the offset and the per-degree factor separately for this reason.
About this calculator
Sources
Checked against references
This calculator includes 5 worked examples with independently sourced answers. They run in the test suite, and you can run them here too.