Temperature Converter
Convert between Celsius, Fahrenheit, Kelvin, and Rankine temperature scales
Temperature Conversion Formulas
Understanding Temperature Scales
Temperature is a measure of the average kinetic energy of particles in a substance. Different temperature scales were developed for various purposes, from scientific research to everyday weather reporting. Understanding how to convert between these scales is essential in science, cooking, engineering, and international communication.
The Celsius scale, used by most of the world, sets water's freezing point at 0° and boiling point at 100° at standard atmospheric pressure. The Fahrenheit scale, common in the United States, sets these at 32° and 212° respectively. Kelvin, the SI unit for temperature, starts at absolute zero—the theoretical point where all molecular motion stops.
This converter handles all major temperature scales instantly, making it easy to work with international recipes, scientific data, weather reports from different countries, or HVAC calculations that use different standards.
Temperature Scale Comparison
Celsius (°C)
Metric scale based on water. Used globally for weather, cooking, and science. 0°C = freezing, 100°C = boiling.
Fahrenheit (°F)
Used in USA for weather and cooking. 32°F = freezing, 212°F = boiling. Body temp is 98.6°F.
Kelvin (K)
Absolute scale for science. 0K = absolute zero (-273.15°C). No degree symbol used.
Rankine (°R)
Absolute scale using Fahrenheit degrees. Used in some engineering applications. 0°R = absolute zero.
Common Temperature Reference Points
| Reference Point | Celsius | Fahrenheit | Kelvin |
|---|---|---|---|
| Absolute Zero | -273.15°C | -459.67°F | 0 K |
| Water Freezes | 0°C | 32°F | 273.15 K |
| Room Temperature | 20-22°C | 68-72°F | 293-295 K |
| Body Temperature | 37°C | 98.6°F | 310.15 K |
| Water Boils | 100°C | 212°F | 373.15 K |
| Oven (Moderate) | 180°C | 350°F | 453.15 K |
Quick Conversion Tips
Rough Celsius to Fahrenheit
Double the Celsius, then add 30 for a quick estimate. 20°C ≈ (20×2)+30 = 70°F (actual: 68°F).
The -40 Crossover
-40° is the same in both Celsius and Fahrenheit—the only point where the two scales meet.
Kelvin Shortcut
Add 273 to Celsius for Kelvin (273.15 for precision). Room temp 20°C = 293K.
Weather Context
0°C/32°F = coat weather, 20°C/68°F = comfortable, 30°C/86°F = hot, 40°C/104°F = heat wave.
Frequently Asked Questions
Why does the US still use Fahrenheit?
Historical inertia and the costs of switching. Fahrenheit was established in the US before metric standardization. While science and medicine use Celsius, everyday weather and cooking still use Fahrenheit due to familiarity and infrastructure.
What is absolute zero and why does it matter?
Absolute zero (0 K or -273.15°C) is the theoretical lowest temperature where all thermal motion stops. It's physically unattainable but crucial in physics, defining the Kelvin scale and helping scientists understand thermodynamics and quantum mechanics.
Why do scientists use Kelvin instead of Celsius?
Kelvin has no negative values, making calculations simpler. Many physics equations require absolute temperature. Gas laws, thermodynamics, and radiation calculations all work more cleanly with Kelvin's absolute zero baseline.
How do I convert cooking temperatures between C and F?
Use the formula F = (C × 9/5) + 32. Common conversions: 180°C = 350°F (moderate oven), 200°C = 400°F (hot oven), 220°C = 425°F (very hot). Most recipes include both for convenience.
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