Temperature Converter
Convert °C, °F and K with the correct formulas — not just a multiplier — including negative temperatures and an absolute-zero check.
- InstantResults update as you type
- 27 categoriesFrom length to data storage
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How to use this tool
Steps for using the Unit Converter.
- Type a number into From — degrees Celsius are preselected. Commas and scientific notation such as 2.5e3 are accepted.
- Pick the units to convert between; the result in degrees Fahrenheit (or whichever unit you choose) updates as you type. Use the swap button to reverse the conversion.
- Set the decimal places, turn on Show formula to see the calculation, and copy or share the result.
- Below the converter, the table lists every temperature unit with its exact definition, and the links open dedicated pages for the most common pairs.
Example
25 degrees Celsius to degrees Fahrenheit
25 °C77 °F
Formula: °F = °C × 9/5 + 32Common use cases
- Weather forecasts and thermostat settings in °C and °F.
- Oven temperatures in recipes (180 °C ≈ 356 °F).
- Science, engineering and colour temperatures in kelvin.
Temperature unit table
| Unit | Symbol | System | Definition |
|---|---|---|---|
| Celsius | °C | Metric | K − 273.15 |
| Fahrenheit | °F | US customary | °C × 9/5 + 32 |
| Kelvin | K | SI | SI base unit; 0 K is absolute zero |
Popular temperature conversions
- Celsius to Fahrenheit converter°F = °C × 9/5 + 32
- Fahrenheit to Celsius converter°C = (°F − 32) × 5/9
- Celsius to kelvin converterK = °C + 273.15
- Kelvin to Celsius converter°C = K − 273.15
- Fahrenheit to kelvin converterK = (°F − 32) × 5/9 + 273.15
- Kelvin to Fahrenheit converter°F = (K − 273.15) × 9/5 + 32
Other unit converters
- Length convertermm · cm · m · km · in · ft · yd · mi · nmi
- Weight convertermg · g · kg · t · oz · lb · st
- Speed converterm/s · km/h · mph · ft/s · kn
- Volume convertermL · L · cm³ · m³ · gal (US) · qt (US) · cup (US) · fl oz (US) · gal (UK) · fl oz (UK)
- Area convertermm² · cm² · m² · km² · in² · ft² · yd² · ac · ha
- Time converterms · s · min · h · d · wk
- Angle converter° · rad · gon · ′ · ″ · tr
- Pressure converterPa · kPa · MPa · bar · mbar · psi · atm · Torr · mmHg
About temperature units
Temperature scales don't share a zero point, so they can't be converted by multiplying alone — each conversion is a scale plus an offset. Water freezes at 0 °C, 32 °F and 273.15 K and boils (at sea level) at 100 °C, 212 °F and 373.15 K: so °F = °C × 9/5 + 32, and K = °C + 273.15.
Kelvin is the SI unit and starts at absolute zero (0 K = −273.15 °C = −459.67 °F), the lowest temperature physically possible; that's why it's written without a degree sign and never goes negative. The converter rejects values below absolute zero instead of showing an impossible result.
A *difference* of 1 °C equals a difference of 1 K, and 1.8 °F. That matters when converting temperature changes rather than temperatures: a 10 °C rise is an 18 °F rise, not 50 °F.
Limitations
- Results are rounded for display only; the calculation keeps full precision (15 significant digits).
Frequently asked questions
At what temperature are Celsius and Fahrenheit equal?
At −40: −40 °C = −40 °F.
What is normal body temperature in Fahrenheit?
37 °C = 98.6 °F.
Can a temperature in kelvin be negative?
No. 0 K is absolute zero, so the converter shows an error for anything colder.
Are these temperature conversions exact?
Each unit is defined from its official definition (for example 1 inch = 2.54 cm exactly). Results are calculated in double precision and only rounded to the decimal places you choose when shown.