Temperature Converter
Convert a temperature between Celsius, Fahrenheit, Kelvin and Rankine all at once, or convert a temperature change, where the rules are different.
°C · °F · K · °R
All 12 Temperature Conversion Formulas
Every pair of the four scales, in both directions. 9/5 = 1.8 and 5/9 ≈ 0.5556.
| From | To | Formula |
|---|---|---|
| Celsius | Fahrenheit | °F = °C × 9/5 + 32 |
| Celsius | Kelvin | K = °C + 273.15 |
| Celsius | Rankine | °R = (°C + 273.15) × 9/5 |
| Fahrenheit | Celsius | °C = (°F − 32) × 5/9 |
| Fahrenheit | Kelvin | K = (°F + 459.67) × 5/9 |
| Fahrenheit | Rankine | °R = °F + 459.67 |
| Kelvin | Celsius | °C = K − 273.15 |
| Kelvin | Fahrenheit | °F = K × 9/5 − 459.67 |
| Kelvin | Rankine | °R = K × 9/5 |
| Rankine | Celsius | °C = (°R − 491.67) × 5/9 |
| Rankine | Fahrenheit | °F = °R − 459.67 |
| Rankine | Kelvin | K = °R × 5/9 |
Converting a Temperature Difference
A temperature reading and a temperature change convert differently. The +32, +273.15 and +459.67 offsets only shift where zero sits, so they cancel out when you subtract two readings. A change converts by degree size alone:
- 1 Celsius degree = 1 kelvin = 1.8 Fahrenheit degrees = 1.8 Rankine degrees
- A 10°C warming is an 18°F warming, not a change to 50°F
Switch the converter to "A temperature change" for heating and cooling rates, weather differences and specific-heat calculations. It accepts negative changes and skips the absolute-zero check, because a change of −300 degrees is perfectly possible.
The Four Scales Compared
Two things define a temperature scale: where zero is and how big one degree is. Celsius and Kelvin share a degree size, and so do Fahrenheit and Rankine. Kelvin and Rankine both start at absolute zero.
| Scale | Zero is | One degree | Used for |
|---|---|---|---|
| Celsius (°C) | Freezing point of water (approx.) | 1 K | Everyday use in almost every country; science |
| Fahrenheit (°F) | A brine mixture, 17.8 °C below freezing | 5/9 K | Everyday use in the US |
| Kelvin (K) | Absolute zero | 1 K | SI unit; physics, chemistry, engineering |
| Rankine (°R) | Absolute zero | 5/9 K | US thermodynamics and aerospace |
From a Record Cold to an Oven, on Four Scales
Record temperatures are the World Meteorological Organization's recognised values.
| Temperature | °C | °F | K | °R |
|---|---|---|---|---|
| Lowest air temperature recorded (Vostok, 1983) | -89.2 | -128.56 | 183.95 | 331.11 |
| Home freezer | -18 | -0.4 | 255.15 | 459.27 |
| Fridge | 4 | 39.2 | 277.15 | 498.87 |
| Human body | 37 | 98.6 | 310.15 | 558.27 |
| Highest air temperature recorded (Death Valley, 1913) | 56.7 | 134.06 | 329.85 | 593.73 |
| Moderate oven | 180 | 356 | 453.15 | 815.67 |
Dedicated Converters for Each Pair
Each pair has its own page with a conversion chart and worked examples for that pair, from oven temperatures to rocket propellants:
Frequently asked questions
Which temperature scale is most accurate?
None. They all describe the same temperature, just with different zero points and degree sizes. Accuracy depends on the thermometer, not the scale.
Why does this converter include Rankine?
Rankine is the absolute scale that goes with Fahrenheit, and it's still used in US engineering. Showing all four makes the pattern clear: two relative scales and two absolute ones.
Why won't it accept −300°C?
That's below absolute zero (−273.15°C), so no real temperature can have that value. If you meant a drop of 300 degrees, switch to "A temperature change".
What is absolute zero on each scale?
−273.15°C, −459.67°F, 0 K and 0°R. It's the lowest possible temperature, which is why the two absolute scales start there.
Sources
- NIST Special Publication 811, Guide for the Use of the International System of Units (SI): temperature scale definitions and conversion formulas.
- World Meteorological Organization: Weather and Climate Extremes Archive: recorded high and low temperatures.
Related Tools
Convert Celsius to Fahrenheit.
Convert Celsius to Kelvin.
Convert Celsius to Rankine.
Convert Fahrenheit to Celsius.
Convert Fahrenheit to Kelvin.
Convert Fahrenheit to Rankine.