Temperature Converter
Convert Celsius, Fahrenheit, and Kelvin — including the classic weather-forecast conversion.
Convert between Celsius (°C), Fahrenheit (°F) and Kelvin (K) instantly. Temperature scales have different zero points, so the conversion uses an offset as well as a multiplier. The formulas and a reference chart are below.
Popular Temperature Conversions
- Celsius to Fahrenheit
- Fahrenheit to Celsius
- Celsius to Kelvin
- Kelvin to Celsius
- Fahrenheit to Kelvin
- Kelvin to Fahrenheit
All Temperature Units
| Unit | Symbol | Definition |
|---|---|---|
| Celsius | °C | A scale where water freezes at 0° and boils at 100° at standard atmospheric pressure. |
| Fahrenheit | °F | A scale where water freezes at 32° and boils at 212° at standard atmospheric pressure. |
| Kelvin | K | The SI base unit of temperature, starting at absolute zero with no negative values. |
The three temperature scales
- Celsius (°C) is used for weather, cooking and science in Pakistan and most of the world. It was historically fixed by the freezing (0 °C) and boiling (100 °C) points of water at standard atmospheric pressure.
- Fahrenheit (°F) is used mainly in the United States for weather, home and body temperature. Water freezes at 32 °F and boils at 212 °F, a span of 180 degrees.
- Kelvin (K) is the SI base unit of thermodynamic temperature and starts at absolute zero (−273.15 °C). Since 2019 it has been defined by fixing the Boltzmann constant at 1.380649 × 10⁻²³ J/K. Kelvin is written without a degree sign.
Temperature conversion formulas
°C = (°F − 32) × 5/9
K = °C + 273.15
°C = K − 273.15
K = (°F − 32) × 5/9 + 273.15
Worked example: convert 37 °C to °F. 37 × 9/5 = 66.6, and 66.6 + 32 = 98.6 °F. Reverse: 98.6 °F → (98.6 − 32) × 5/9 = 37 °C.
Mental shortcut for weather: °C to °F — double it and add 30 (25 °C → 80 °F; exact 77). °F to °C — subtract 30 and halve it. The shortcut is only reliable roughly between 0 and 30 °C.
Reference chart
| Celsius | Fahrenheit | Kelvin | What it means |
|---|---|---|---|
| -273.15 °C | -459.67 °F | 0 K | Absolute zero |
| -40 °C | -40 °F | 233.15 K | Same in °C and °F |
| 0 °C | 32 °F | 273.15 K | Water freezes |
| 20 °C | 68 °F | 293.15 K | Room temperature |
| 25 °C | 77 °F | 298.15 K | Warm day |
| 37 °C | 98.6 °F | 310.15 K | Normal body temperature (approx.) |
| 38 °C | 100.4 °F | 311.15 K | Fever threshold (common) |
| 45 °C | 113 °F | 318.15 K | Extreme summer heat |
| 100 °C | 212 °F | 373.15 K | Water boils (sea level) |
Cooking and oven temperatures
| Celsius | Fahrenheit |
|---|---|
| 160 °C | 320 °F |
| 170 °C | 338 °F |
| 180 °C | 356 °F |
| 190 °C | 374 °F |
| 200 °C | 392 °F |
| 220 °C | 428 °F |
| 230 °C | 446 °F |
Recipes from the US give oven temperatures in °F while most Pakistani ovens and recipe sites use °C. Fan (convection) ovens usually run about 20 °C (around 25 °F) cooler than the recipe says for a conventional oven. Check your oven manual.
Common mistakes to avoid
- Converting a temperature change. A rise of 10 °C is a rise of 18 °F. Only the 9/5 factor applies, with no +32, because the offset cancels in a difference.
- Forgetting the order of operations. For °C to °F, multiply first and then add 32. 37 + 32 and then × 9/5 is wrong.
- Writing "degrees Kelvin". The correct form is "kelvin" (K), not "degrees Kelvin".
- Fever readings. A thermometer set to °F reading 100.4 is 38 °C. Check which scale the device displays before acting on a reading, and follow medical advice rather than a conversion.
Sources: BIPM, The International System of Units (SI Brochure), 9th edition; NIST Special Publication 811.
Frequently Asked Questions
How do I convert Celsius to Fahrenheit?
Multiply the Celsius value by 9/5 (1.8) and add 32. For example, 25 °C × 1.8 + 32 = 77 °F.
How do I convert Fahrenheit to Celsius?
Subtract 32 and multiply by 5/9. For example, 100 °F − 32 = 68, and 68 × 5/9 = 37.778 °C.
At what temperature are Celsius and Fahrenheit equal?
−40. At that point −40 °C equals −40 °F.
What is 0 °C in Kelvin?
0 °C is 273.15 K. Add 273.15 to a Celsius value to get kelvin.
What is normal body temperature in Fahrenheit?
About 98.6 °F, which is 37 °C. Individual normal temperature varies by person and time of day.
What is 45 °C in Fahrenheit?
45 °C = 113 °F.
What is absolute zero?
Absolute zero is 0 K, which is −273.15 °C or about −459.67 °F, the lowest possible thermodynamic temperature.
All Temperature Conversions
Choose a starting unit to see every conversion available from it.