Fever Temperature Converter: °F to °C
জ্বরের তাপমাত্রা: ফারেনহাইট থেকে সেলসিয়াস
Convert a thermometer reading between °F and °C and see whether it counts as a fever by the NHS 38 °C (100.4 °F) rule.
More Health calculatorsThe conversion will appear here
Enter a temperature, then select Convert.
Fahrenheit to Celsius: the formula
°C = (°F − 32) × 5 ÷ 9, and the other way °F = °C × 9 ÷ 5 + 32.
Example: 102 °F
- 102 − 32 = 70.
- 70 × 5 ÷ 9 = 38.89 °C.
- That is above 38 °C, so it is a high temperature (fever) by the NHS definition.
Thermometer readings in °F and °C
| °F | °C | By the NHS definition |
|---|---|---|
| 97 | 36.11 | Not a fever |
| 98 | 36.67 | Not a fever |
| 98.6 | 37.00 | Not a fever |
| 99 | 37.22 | Not a fever |
| 100 | 37.78 | Not a fever |
| 100.4 | 38.00 | Fever |
| 101 | 38.33 | Fever |
| 102 | 38.89 | Fever |
| 103 | 39.44 | Fever |
| 104 | 40.00 | Fever |
| 105 | 40.56 | Fever |
Note that a “100 degree fever” is 37.78 °C, just under the 38 °C line. A line is used because body temperature varies a little from person to person and through the day.
Fever in babies: when not to wait
The NHS says to get medical help straight away if:
- a baby under 3 months has a temperature of 38 °C (100.4 °F) or higher;
- a baby of 3 to 6 months has 39 °C (102.2 °F) or higher.
For adults, see a doctor if a high temperature isn’t getting better with care at home, or is getting worse. In Bangladesh, contact a doctor or your nearest health centre. This page does not diagnose anything.
Other useful calculators
To find a child’s age in months and days, use the Age Calculator; for adults’ weight and height, the BMI Calculator.
How to use the calculator
- Choose what your thermometer reads in: °F or °C.
- Enter the temperature, e.g. 102. Bangla digits work.
- Select Convert to see the other unit and, for a body temperature, whether it counts as a fever.
Sources
- NHS: High temperature (fever) in adults (reviewed 19 October 2026).
- NHS: High temperature (fever) in children (reviewed 3 January 2024).
Checked on 1 November 2026.
Frequently asked questions
What temperature is a fever?
The NHS says a high temperature (fever) is 38 °C or above, which is 100.4 °F, for adults and children. You can still have a high temperature below that if you feel hot, cold or shivery.
Is 100 °F a fever?
100 °F is 37.78 °C, just under the NHS’s 38 °C line, so it doesn’t count as a high temperature by that rule. 100.4 °F (38 °C) and above does.
How do I convert °F to °C?
Subtract 32, multiply by 5 and divide by 9. 102 °F: (102 − 32) × 5 ÷ 9 = 38.89 °C. For °C to °F, multiply by 9, divide by 5 and add 32.
Why is the line 38 °C and not 37 °C?
Body temperature varies a little from person to person and through the day, so a reading slightly above 37 °C (98.6 °F) is not by itself a fever. The NHS uses 38 °C (100.4 °F) as the line for a high temperature.
When should a baby with a fever see a doctor?
The NHS says to get medical help straight away if a baby under 3 months has 38 °C or higher, or a baby of 3 to 6 months has 39 °C or higher. In Bangladesh, contact a doctor or your nearest health centre.
Does this tell me what is wrong?
No. It only converts the reading and compares it with the NHS fever line. It is not a diagnosis. If you are worried, or a fever lasts or gets worse, see a doctor.
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