What the Temperature Converter Does

This temperature converter changes a value between the three temperature scales used in everyday life and science: Celsius (°C), Fahrenheit (°F) and Kelvin (K). Type a number into one field and the equivalent values in the other two scales appear instantly.

It is useful for students checking physics or chemistry homework, cooks following a recipe written for another country's oven, travelers reading a foreign weather forecast, and anyone working with thermostats, lab equipment, or HVAC settings. If you searched for a celsius to fahrenheit tool or a quick c to f answer, this does both directions plus Kelvin.

How It Works: The Conversion Formulas

The scales are linear relative to each other but they do not share the same zero point or the same degree size, so you cannot simply multiply by a single factor. Each conversion uses its own formula:

Celsius to Fahrenheit: F = C × 9/5 + 32
Fahrenheit to Celsius: C = (F − 32) × 5/9
Celsius to Kelvin: K = C + 273.15
Kelvin to Celsius: C = K − 273.15
Fahrenheit to Kelvin: convert F to C first, then add 273.15

Reference Points to Sanity-Check Your Answer

Knowing a few fixed points makes it easy to tell whether a converted value looks right. Water freezes and boils at well-defined temperatures on every scale.

Water freezes at 0 °C, which is 32 °F and 273.15 K. Water boils (at sea level) at 100 °C, which is 212 °F and 373.15 K. Normal human body temperature is about 37 °C or 98.6 °F. Absolute zero, the coldest possible temperature, is 0 K, equal to −273.15 °C or −459.67 °F.

Worked Example: 25 °C to Fahrenheit and Kelvin

Suppose a weather app shows 25 °C and you want both Fahrenheit and Kelvin.

For Fahrenheit: F = 25 × 9/5 + 32. First, 25 × 9/5 = 45. Then 45 + 32 = 77, so 25 °C = 77 °F. For Kelvin: K = 25 + 273.15 = 298.15 K. Going the other way to confirm: (77 − 32) × 5/9 = 45 × 5/9 = 25 °C, which matches.

Common Mistakes and Practical Tips

Most errors come from the order of operations or mixing up the constants. A few things to watch for:

Always multiply by 9/5 before adding 32 (or subtract 32 before multiplying by 5/9). Skipping the order gives a wrong answer.
Use 273.15, not a rounded 273, when accuracy matters in science; the 0.15 shifts results in chemistry and physics.
Kelvin is never written with a degree symbol or as 'degrees' — it is just 'K' (for example, 298.15 K).
For a fast mental estimate of C to F, double the Celsius value and add 30 (25 °C ≈ 80 °F). It is close but not exact; use the full formula for precise work.
Negative temperatures are normal in Celsius and Fahrenheit but not in Kelvin, since 0 K is absolute zero — a negative Kelvin result means an input error.