Celsius to Fahrenheit Converter

Formula

°F = (°C × 9/5) + 32

The reverse conversion:

°C = (°F − 32) × 5/9

Formula variables

• °C — temperature in degrees Celsius.
• °F — equivalent temperature in degrees Fahrenheit.
• 9/5 — the ratio of one Celsius degree to one Fahrenheit degree. One Fahrenheit degree equals 5/9 of a Celsius degree.
• 32 — the offset between the two scales' zero points. Water freezes at 0 °C and 32 °F.

Worked Examples

Example 1: Freezing point of water

1. Start: 0 °C.
2. Apply: (0 × 9/5) + 32 = 0 + 32.
3. Result: 0 °C = 32 °F.

Example 2: Boiling point of water

1. Start: 100 °C.
2. Apply: (100 × 9/5) + 32 = 180 + 32.
3. Result: 100 °C = 212 °F.

Example 3: Human body temperature

1. Start: 37 °C.
2. Apply: (37 × 9/5) + 32 = 66.6 + 32.
3. Result: 37 °C = 98.6 °F. This is the average human core body temperature.

Example 4: Room temperature

1. Start: 20 °C.
2. Apply: (20 × 9/5) + 32 = 36 + 32.
3. Result: 20 °C = 68 °F.

Example 5: The −40 intersection

1. Start: −40 °C.
2. Apply: (−40 × 9/5) + 32 = −72 + 32.
3. Result: −40 °C = −40 °F. This is the only temperature where the two scales show identical numbers.

Common Conversion Chart

Real-World Uses

• Cooking: Oven temperatures in European recipes are given in Celsius; US ovens are labeled in Fahrenheit. A recipe calling for 180 °C (fan) is roughly 355 °F.
• Weather: Weather forecasts in the US use Fahrenheit; most other countries use Celsius. Converting helps when reading foreign forecasts or comparing climate data.
• Medicine: Fever thresholds differ between Celsius and Fahrenheit documentation. Body temperature 38 °C is 100.4 °F, a common fever threshold.
• Industrial processes: Manufacturing specifications may use either scale depending on country.

Unit Definitions

Celsius (°C)

A temperature scale where 0 °C is defined as the freezing point of water and 100 °C as its boiling point at 1 standard atmosphere. The scale is named after Anders Celsius (1701–1744). The SI accepts Celsius as a derived unit, with °C = K − 273.15.

Fahrenheit (°F)

A temperature scale where 32 °F is the freezing point of water and 212 °F the boiling point at 1 standard atmosphere. Named after Daniel Gabriel Fahrenheit (1686–1736). It is used officially in the United States, and informally in a few other countries.

Accuracy and Rounding

The relationship between Celsius and Fahrenheit is exactly defined: 1 Celsius degree is exactly 9/5 of a Fahrenheit degree, and the offset is exactly 32. Because the Celsius-to-Fahrenheit conversion is linear, any Celsius value has an exact Fahrenheit equivalent (subject to floating-point representation).

Note that Celsius and Fahrenheit are nonlinear relative to Kelvin — the Celsius and Fahrenheit scales have arbitrary zero points. Kelvin is the absolute-temperature scale, and is the correct choice for scientific calculations. The converter uses explicit forward and reverse functions for all temperature conversions; it does not use scale-factor multiplication.

Related Converters

• Fahrenheit to Celsius — the reverse conversion
• Celsius to Kelvin — absolute temperature
• Kelvin to Celsius
• All Temperature Converters

Frequently Asked Questions