How do you convert between Celsius and Fahrenheit?

In one line

The rule

To convert Celsius (°C) to Fahrenheit (°F): °F = (°C × 9⁄5) + 32 To convert Fahrenheit (°F) to Celsius (°C): °C = (°F − 32) × 5⁄9

• °F = (°C × 9⁄5) + 32 (Celsius to Fahrenheit)
• °C = (°F − 32) × 5⁄9 (Fahrenheit to Celsius)

Let's understand it simply

Imagine you are in Delhi in May. The weather report says it is 40°C. But your cousin in the US says it is 104°F there. Both are talking about how hot it is, but using different scales. Celsius is common in India. Fahrenheit is used in the US. The formulas above help you talk in the same language.

Think of Celsius as how water behaves: 0°C is when water freezes, 100°C is when it boils. Fahrenheit uses 32°F for freezing and 212°F for boiling. The formulas help match these points.

How it works

1. To go from Celsius to Fahrenheit:
2. Multiply the Celsius temperature by 9.
3. Divide the result by 5.
4. Add 32 to this number. That is the Fahrenheit value.
5. To go from Fahrenheit to Celsius:
6. Subtract 32 from the Fahrenheit temperature.
7. Multiply that number by 5.
8. Divide the result by 9. That is the Celsius value.

The story behind it

The Celsius scale was made by Anders Celsius, a Swedish scientist, in 1742. He set 0°C for freezing water and 100°C for boiling. Fahrenheit was made by Daniel Gabriel Fahrenheit, a German scientist, in 1724. He used 32°F for freezing and 212°F for boiling water. People needed a way to compare temperatures, so these formulas were made.

Where you see it in real life

• Weather apps: Sometimes show both °C and °F, especially for international users.
• Cooking: Some ovens or recipes use Fahrenheit (like 350°F), others use Celsius (like 180°C).
• Science labs: Experiments may use either scale, depending on the country or book.
• Thermometers: Some show both scales side by side.
• Talking to relatives abroad: They may use Fahrenheit, so you need to convert.
• International travel: Weather reports in other countries may use a different scale.

Why it matters

• Helps you understand temperature reports from around the world.
• Needed for science, cooking, and travel.
• Useful for exams and practicals in school.
• Makes it easier to follow instructions from books or videos from other countries.

Worked example

Let's convert 25°C to Fahrenheit and 77°F to Celsius.

Given: °C = 25
Step 1: Use the formula      °F = (°C × 9⁄5) + 32
Step 2: Calculate           °F = (25 × 9⁄5) + 32
Step 3: Multiply            25 × 9 = 225
Step 4: Divide              225 ÷ 5 = 45
Step 5: Add 32              45 + 32 = 77
Answer:                     25°C = 77°F

Given: °F = 77
Step 1: Use the formula      °C = (°F − 32) × 5⁄9
Step 2: Subtract 32          77 − 32 = 45
Step 3: Multiply by 5        45 × 5 = 225
Step 4: Divide by 9          225 ÷ 9 = 25
Answer:                     77°F = 25°C

Common mistakes

• Forgetting to add or subtract 32 in the formula.
• Mixing up which formula to use for which direction.
• Not following the order of operations (multiply/divide before adding/subtracting).
• Using the wrong scale for boiling and freezing points.

Remember it

"C to F: times 9, divide by 5, add 32. F to C: minus 32, times 5, divide by 9."