Celsius, Fahrenheit, and Kelvin: Understanding Temperature Scales
A comprehensive guide to the three main temperature scales, their history, and how to convert between them.
Temperature is one of the most commonly measured physical quantities, yet different parts of the world use different scales to measure it. Understanding all three major temperature scales helps you navigate cooking, weather, science, and international travel.
Celsius (°C)
The Celsius scale, invented by Swedish astronomer Anders Celsius in 1742, is the most widely used temperature scale worldwide. It is based on the properties of water: 0°C is the freezing point and 100°C is the boiling point at standard atmospheric pressure.
Celsius is used by most countries for weather reports, cooking, and everyday temperature measurements. It is also the standard in scientific research when absolute precision is not required.
Fahrenheit (°F)
The Fahrenheit scale, created by Daniel Gabriel Fahrenheit in 1724, is primarily used in the United States and a few other countries. On this scale, water freezes at 32°F and boils at 212°F.
While Fahrenheit may seem arbitrary, it actually provides more precision for everyday temperatures since the degree increments are smaller. The range from 0°F to 100°F roughly covers the extremes of weather temperatures in temperate climates.
Kelvin (K)
The Kelvin scale is the scientific standard for temperature measurement. It starts at absolute zero (0 K = -273.15°C), the theoretical lowest possible temperature where all molecular motion stops. The Kelvin scale uses the same increment size as Celsius but starts from absolute zero instead of the freezing point of water.
Kelvin is essential in physics, chemistry, and engineering calculations. Note that Kelvin does not use a degree symbol — it is simply written as K.
Conversion Formulas
- 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
Useful Temperature References
| Temperature | 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 |
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