How do you convert Celsius to Fahrenheit?

To convert Celsius to Fahrenheit, use the formula: °F = (°C × 9/5) + 32. For example, 100°C = (100 × 9/5) + 32 = 180 + 32 = 212°F. The quick mental shortcut: double the Celsius value and add 30 (gives an approximation).

Why does the United States use Fahrenheit instead of Celsius?

The US uses Fahrenheit because it was the standard temperature scale when the country was founded in the 18th century. When most of the world switched to the Celsius scale (the Metric System) in the 20th century, the US did not adopt the change. Today, Fahrenheit is used in only a handful of countries: the US, Bahamas, Belize, Palau, Micronesia, and the Marshall Islands.

What is absolute zero in Celsius?

Absolute zero is -273.15°C, or 0 Kelvin (K). It is the theoretical lowest possible temperature, where all molecular motion stops. It is equivalent to -459.67°F.

Temperature Converter — Celsius, Fahrenheit, Kelvin & Why Countries Differ

Temperature Converter

Convert between all major temperature scales instantly. See why only the US and a few other countries still use Fahrenheit, while 195+ nations use Celsius.

Quick Answer

°C to °F: multiply by 9/5 then add 32. °F to °C: subtract 32 then multiply by 5/9. Key references: 0°C = 32°F (freezing), 100°C = 212°F (boiling), 37°C = 98.6°F (body temp). Only the US, Liberia, and Myanmar still officially use Fahrenheit.

Temperature Value

Convert From

📌 Common Reference Points

Point	°C	°F	K
Water Freezes	0	32	273.15
Room Temperature	22	71.6	295.15
Human Body	37	98.6	310.15
Water Boils	100	212	373.15
Absolute Zero	-273.15	-459.67	0

Why Does the US Use Fahrenheit While the Rest of the World Uses Celsius?

The short answer: history and inertia. Fahrenheit was developed in 1724 by Daniel Fahrenheit, a German physicist. It was the dominant temperature scale in the English-speaking world for centuries.

In 1790, the French Academy of Sciences developed the metric system including Celsius (then called "centigrade"). Over the 19th and 20th centuries, most nations switched to Celsius as part of broader metrication.

The United States officially tried to switch to metric in the 1970s with the Metric Conversion Act of 1975, but the transition was voluntary and largely failed due to public resistance and lack of enforcement. As a result, the US remains one of only three countries in the world that has not officially adopted the metric system — the others being Liberia and Myanmar.

Temperature Scales: A Brief History

Fahrenheit (1724): 0°F was originally set to the freezing point of a brine solution. 96°F was roughly human body temperature. Later calibrated so water freezes at 32°F and boils at 212°F.
Celsius (1742): Originally called "centigrade." Water freezes at 0°C and boils at 100°C — an elegantly simple scale. Renamed "Celsius" in 1948 after Anders Celsius.
Kelvin (1848): The absolute temperature scale used in science. 0 K (absolute zero) is the lowest theoretically possible temperature. K = °C + 273.15.
Réaumur (1730): Once popular in Europe, especially France and Germany. Water freezes at 0°Ré, boils at 80°Ré. Now almost entirely obsolete.

Quick Conversion Reference

The fastest mental conversions:

°C to °F: Multiply by 1.8 (or 9/5), then add 32
°F to °C: Subtract 32, then multiply by 0.556 (or 5/9)
°C to K: Add 273.15
Quick approximation C→F: Double the °C value and add 30 (off by a few degrees but faster)