The Celsius to Fahrenheit Formula
To convert Celsius to Fahrenheit: °F = (°C × 9/5) + 32
To convert Fahrenheit to Celsius: °C = (°F − 32) × 5/9
For a quick mental estimate: double the Celsius value and add 30. Example: 20°C → 40 + 30 = 70°F (actual: 68°F). Close enough for casual use.
Common Temperature Reference Chart
| Celsius | Fahrenheit | Description | |---|---|---| | -40°C | -40°F | Celsius and Fahrenheit intersect | | 0°C | 32°F | Water freezes | | 20°C | 68°F | Room temperature (comfortable) | | 37°C | 98.6°F | Normal human body temperature | | 100°C | 212°F | Water boils (at sea level) | | 180°C | 356°F | Oven: moderate baking | | 220°C | 428°F | Oven: high heat |
Why Do the US and Europe Use Different Scales?
The Fahrenheit scale was created by Daniel Gabriel Fahrenheit in 1724 and became standard in English-speaking countries. The Celsius scale (originally Centigrade) was proposed by Anders Celsius in 1742 and adopted by most of the world through the metric system. Only the US, Belize, the Cayman Islands, and Palau still officially use Fahrenheit.
Kelvin: The Scientific Temperature Scale
Kelvin is the base unit of temperature in the International System of Units (SI). It starts at absolute zero — the coldest possible temperature (-273.15°C). Scientists use Kelvin because it has no negative values, making mathematical calculations cleaner.
To convert Celsius to Kelvin: K = °C + 273.15. Room temperature of 20°C = 293.15 K.
Use the RoughTools Temperature Converter to instantly convert between Celsius, Fahrenheit, Kelvin, and Rankine.