Conversion
Temperature Converter
Convert between Fahrenheit, Celsius, and Kelvin instantly. Type any value, the other units update in real time. No rounding errors, no sign-up required.
Common Reference Points (click to load)
| Reference | °C | °F | K |
|---|---|---|---|
| Absolute zero | -273.15 | -459.67 | 0 |
| Water freezes | 0 | 32 | 273.15 |
| Room temperature | 22 | 71.6 | 295.15 |
| Body temperature | 37 | 98.6 | 310.15 |
| Water boils | 100 | 212 | 373.15 |
Common Temperature References
Some temperatures come up constantly in everyday life. Use the reference table in the converter above to load any of these instantly, or refer to the values below.
Body temperature
37°C / 98.6°F / 310.15 K, normal average for adults.
Water boiling point
100°C / 212°F / 373.15 K, at sea-level pressure.
Water freezing point
0°C / 32°F / 273.15 K, the basis of the Celsius scale.
Absolute zero
-273.15°C / -459.67°F / 0 K, the lowest possible temperature.
Understanding Temperature Scales
Fahrenheit is the primary temperature scale used in the United States for everyday weather, cooking, and body temperature. It was defined with 32°F as the freezing point of water and 212°F as the boiling point, giving a 180-degree span between those two fixed points.
Celsius (formerly Centigrade) is the standard in most of the world and all scientific contexts outside the US. Its two anchor points, 0°C (freezing) and 100°C (boiling), make it intuitive for everyday use. Kelvin shares the same degree size as Celsius but starts at absolute zero (0 K = -273.15°C), making it the preferred unit in physics, chemistry, and engineering where negative temperatures are meaningless or inconvenient.
The Conversion Formulas Explained
Behind every field in the converter above is one of three linear formulas. Each one takes a value in one scale and returns the equivalent in another by applying a fixed multiplier and, in two of the three cases, a fixed offset. Understanding the formulas helps explain why some conversions round cleanly (Celsius to Kelvin) while others rarely land on a whole number (Fahrenheit to Celsius).
Fahrenheit and Celsius
°C = (°F − 32) × 5/9 · °F = (°C × 9/5) + 32
These two scales were both defined using two fixed reference points, but different ones. Fahrenheit originally used a brine mixture (0°F) and human body temperature (96°F) as anchors; Celsius uses water's freezing point (0°C) and boiling point (100°C). Because the intervals differ (180 Fahrenheit degrees vs. 100 Celsius degrees between freezing and boiling), the 9/5 ratio and the 32-degree offset are both needed to convert accurately.
Celsius and Kelvin
K = °C + 273.15 · °C = K − 273.15
Kelvin and Celsius share the exact same degree size, so converting between them is just addition or subtraction, no multiplication needed. The offset of 273.15 places 0 K at absolute zero, the point at which atoms have minimum vibrational motion, which corresponds to −273.15°C.
Fahrenheit and Kelvin (combined)
K = (°F − 32) × 5/9 + 273.15
There is no direct Fahrenheit-to-Kelvin constant. The tool above converts internally through Celsius: it takes whichever field you edit, resolves it to Celsius first, then derives the other two units from that single value. This avoids compounding rounding errors that can occur when chaining separate formulas.
Worked example
Take a summer day at 30°C. Celsius to Fahrenheit: (30 × 9/5) + 32 = 86°F. Celsius to Kelvin: 30 + 273.15 = 303.15 K. If instead you started from 86°F and worked backward, subtracting 32 gives 54, and 54 × 5/9 gives exactly 30°C again, confirming the two formulas are true inverses of each other.