Fahrenheit to Celsius Converter
Bidirectional temperature converter between Fahrenheit, Celsius, and Kelvin. Type in any field to update the others live.
No data sent to serverAbout Temperature Scales
The Celsius scale was proposed by Swedish astronomer Anders Celsius in 1742. It sets 0°C at the freezing point of water and 100°C at the boiling point at standard atmospheric pressure. Celsius is the everyday temperature unit used in almost every country in the world, including all of Europe, Asia, Africa, South America, and Oceania.
The Fahrenheit scale was developed by Daniel Gabriel Fahrenheit in 1724. On this scale, water freezes at 32°F and boils at 212°F, giving a 180-degree span between the two phase transitions. Fahrenheit remains the primary everyday scale in the United States, along with a few other places such as the Bahamas, the Cayman Islands, and Liberia.
The Kelvin scale is the SI base unit for temperature, introduced by William Thomson (Lord Kelvin) in 1848. It starts at absolute zero (0 K = −273.15°C), the theoretical point where molecular motion stops. Kelvin has the same degree size as Celsius but no negative values, which makes it the standard for science, physics, chemistry, and engineering.
How to Convert
- Fahrenheit to Celsius: °C = (°F − 32) × 5/9
- Celsius to Fahrenheit: °F = °C × 9/5 + 32
- Celsius to Kelvin: K = °C + 273.15
- Kelvin to Celsius: °C = K − 273.15
- Fahrenheit to Kelvin: K = (°F − 32) × 5/9 + 273.15
- Kelvin to Fahrenheit: °F = (K − 273.15) × 9/5 + 32
A quick mental shortcut: to roughly convert Fahrenheit to Celsius, subtract 30 and divide by 2. To go from Celsius to Fahrenheit, double it and add 30. The result is within a few degrees of the exact value for most everyday temperatures.
Common Reference Points
Memorizing a handful of anchor points makes on-the-fly conversion much easier. Water freezes at 0°C = 32°F and boils at 100°C = 212°F. Normal human body temperature is 37°C = 98.6°F. Comfortable room temperature ranges from roughly 20–22°C (68–72°F). A hot summer day hits 35°C = 95°F, and a freezing winter day can dip to −10°C = 14°F.
Why Is Fahrenheit Still Used?
The United States kept Fahrenheit largely for cultural and infrastructure inertia. When most of the world adopted the metric system during the 20th century, the US had already built enormous industrial, educational, and consumer ecosystems around Fahrenheit and imperial units. Changing weather reports, recipes, thermostats, and schooling on a national scale was deemed too disruptive and expensive.
Some Americans argue Fahrenheit is better suited to describing ambient air temperature — 0°F is a genuinely cold day, 100°F is genuinely hot, and the scale has finer granularity without needing decimals. Celsius fans counter that tying the scale to water's freezing and boiling points is more intuitive for cooking, science, and weather below freezing. Both scales work; the difference is mostly familiarity.
Frequently Asked Questions
What's the exact formula for Fahrenheit to Celsius? °C = (°F − 32) × 5/9. For example, 100°F → (100 − 32) × 5/9 = 37.78°C.
Why does the US use Fahrenheit? Historical and practical inertia. The US industrialized before the metric system became dominant, and the cost and disruption of switching weather reports, recipes, and thermostats has kept Fahrenheit in everyday use, even though US science and medicine use Celsius and Kelvin.
What is Kelvin used for? Kelvin is the SI base unit for temperature and is used in physics, chemistry, astronomy, and engineering. It starts at absolute zero, which makes calculations involving gas laws, thermodynamics, and black-body radiation cleaner because there are no negative temperatures.
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