Temperature Converter
Convert between Celsius, Fahrenheit, and Kelvin instantly. Accurate temperature conversion tool.
Enter a temperature and select the unit to see conversions to all other scales.
°F (Fahrenheit)
212.00 °F
K (Kelvin)
373.15 K
The Formulas (in Plain English)
Three temperature scales matter in everyday life. Celsius is what most of the world uses. Fahrenheit is the US holdout. Kelvin is for scientists. Here's how they connect:
°F = (°C × 9/5) + 32
Celsius to Fahrenheit
°C = (°F - 32) × 5/9
Fahrenheit to Celsius
K = °C + 273.15
Celsius to Kelvin
Mental math shortcut: To get a rough Fahrenheit from Celsius, double the number and add 30. So 20°C ≈ 70°F (actual: 68°F). Close enough for weather chat.
Temperature Cheat Sheet
Bookmark this — it covers the conversions people look up most:
| Context | °C | °F | K |
|---|---|---|---|
| Absolute zero | -273.15 | -459.67 | 0 |
| Water freezes | 0 | 32 | 273.15 |
| Fridge temperature | 3-5 | 37-41 | 276-278 |
| Room temperature | 20-22 | 68-72 | 293-295 |
| Body temperature | 37 | 98.6 | 310.15 |
| Fever threshold | 38 | 100.4 | 311.15 |
| Moderate oven | 180 | 356 | 453.15 |
| Hot oven | 220 | 428 | 493.15 |
| Water boils | 100 | 212 | 373.15 |
| C and F are equal | -40 | -40 | 233.15 |
Why Three Different Scales Exist
Fahrenheit (1724): Daniel Fahrenheit set 0° at the coldest temperature he could reliably create (a brine solution) and 96° at human body temperature. The scale stuck in English-speaking countries and the US never switched.
Celsius (1742): Anders Celsius designed a 0-100 scale anchored to water's freezing and boiling points. It's elegant, intuitive, and now used by most of the world. Originally his scale was inverted (100 for freezing, 0 for boiling) — Linnaeus flipped it a year later.
Kelvin (1848): Lord Kelvin started at absolute zero — the point where molecular motion stops. It's the same degree size as Celsius, just shifted by 273.15. Scientists use it because you can't have negative energy, and Kelvin avoids negative temperatures that break equations.
Common Conversion Scenarios
Following a US recipe
American recipes use Fahrenheit. 350°F = 177°C (round to 180°C). 400°F = 204°C (round to 200°C). 425°F = 218°C (round to 220°C). For precise oven temperatures including Gas Mark, try our Oven Temperature Converter.
Reading US weather forecasts
US weather is in Fahrenheit. Quick guide: 50°F = 10°C (jacket weather), 70°F = 21°C (comfortable), 85°F = 29°C (warm), 100°F = 38°C (dangerously hot). If the forecast says "feels like 105°F", that's 40.5°C — stay inside.
Checking for a fever
A fever starts at 38°C / 100.4°F for adults. High fever is 39.5°C / 103°F. Seek medical help above 40°C / 104°F. If your thermometer shows Fahrenheit and you think in Celsius (or vice versa), use this converter for peace of mind.
Science homework or lab work
Lab reports typically use Kelvin or Celsius. Room temperature is 293-295K (20-22°C). Standard temperature and pressure (STP) is 273.15K (0°C). Remember: you can't have negative Kelvin in classical thermodynamics.
Related Tools
How to use this tool
Enter a temperature value in the input field
Select the source unit (°C, °F, or K)
View instant conversions to all other temperature scales
Common uses
- Converting weather forecasts between Celsius and Fahrenheit
- Setting oven temperatures for international recipes
- Converting scientific measurements to Kelvin
- Understanding body temperature readings in different units
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