Celsius to Fahrenheit

How to Convert Celsius to Fahrenheit?

To convert Celsius to Fahrenheit, multiply the temperature in degrees Celsius by 9/5 (or 1.8) and then add 32. The formula is °F = °C × 9/5 + 32. For example, 20°C equals 68°F. This conversion is one of the most searched unit conversions in the world because Celsius and Fahrenheit are the two dominant temperature scales used in daily life. Most of the world uses Celsius for weather, cooking, and science, while the United States, its territories, and a handful of other countries still rely on Fahrenheit. Whether you are checking the weather forecast before a trip to the US, adjusting a European recipe for an American oven, or trying to understand why your overseas friend says 30 degrees is "hot," knowing how to convert between these two scales is an essential everyday skill. Two checkpoints make this conversion easier to sanity-check: every increase of 1°C equals 1.8°F, and the freezing and boiling anchors are 0°C = 32°F and 100°C = 212°F. In practice, that means small Celsius changes can look larger in Fahrenheit forecasts, and common recipe temperatures often round to nearby American oven settings such as 180°C ≈ 350°F and 200°C ≈ 400°F.

How to Convert Celsius to Fahrenheit

1. Write down the temperature in Celsius that you want to convert.
2. Multiply the Celsius value by 9, then divide the result by 5. Alternatively, multiply by 1.8 — the result is identical.
3. Add 32 to the number you calculated in the previous step.
4. The result is the temperature expressed in degrees Fahrenheit.
5. Quick estimation shortcut: double the Celsius value and add 30. This gives you a rough Fahrenheit figure that is accurate enough for casual use. For instance, 20°C → 20 × 2 + 30 = 70°F (the exact answer is 68°F, so the estimate is close).

Real-World Examples

Key Temperatures: Celsius to Fahrenheit

Related Converters

History of Celsius and Fahrenheit

The Celsius scale was devised in 1742 by Swedish astronomer Anders Celsius. Interestingly, his original scale was inverted — 0 degrees marked the boiling point of water and 100 degrees marked the freezing point. After Celsius's death, fellow Swedish scientist Carl Linnaeus (or possibly Daniel Ekström) reversed the scale to the form we use today, where 0° is freezing and 100° is boiling. The scale was originally called "centigrade" because of its 100-degree interval between the freezing and boiling points of water, but it was officially renamed to "Celsius" in 1948 to avoid confusion with the centesimal grade used in angular measurement. The Fahrenheit scale is older, created in 1724 by Daniel Gabriel Fahrenheit, a Polish-born Dutch-German physicist and instrument maker. Fahrenheit based his scale on three reference points: the temperature of a brine solution (a mix of ice, water, and ammonium chloride) set as 0°F, the freezing point of pure water at 32°F, and the average human body temperature, which he initially placed at 96°F (later refined to 98.6°F). Fahrenheit chose these seemingly odd reference points because they allowed him to avoid negative numbers for most everyday temperatures in the northern European climate where he lived and worked. Today, virtually every country in the world has adopted Celsius as its official temperature scale, following the metric system. The United States remains the most notable holdout, using Fahrenheit in weather reports, cooking, and everyday life, though American scientists use Celsius (and Kelvin) in their work.

Common Mistakes to Avoid

• Forgetting to add 32 after multiplying. The formula has two steps — multiply by 9/5 AND add 32. Skipping the addition of 32 produces a result that is always 32 degrees too low.
• Using ×2 instead of ×9/5 for precise conversions. Doubling is a handy mental shortcut, but it introduces an error of about 10% that compounds at higher temperatures. At 100°C, doubling gives 200 instead of the correct 180 (before adding 32).
• Confusing the direction of conversion. The Celsius-to-Fahrenheit formula is °F = °C × 9/5 + 32. The reverse (Fahrenheit to Celsius) uses subtraction and the reciprocal fraction. Mixing them up gives wildly wrong results.
• Rounding 9/5 to 2 for exact calculations. While 1.8 and 9/5 are identical, rounding up to 2 introduces a meaningful error, especially at temperatures far from zero.
• Assuming a 1:1 relationship between the scales. A change of 1°C equals a change of 1.8°F, not 1°F. This means a 10-degree Celsius swing is actually an 18-degree Fahrenheit swing.

Frequently Asked Questions

Further Reading