Celsius to Fahrenheit Converter – Free Online Temperature Calculator

Convert temperatures between Celsius (°C), Fahrenheit (°F), and Kelvin (K) instantly with our free online temperature converter. Whether you’re checking the weather, following a recipe, or working on scientific calculations, get accurate conversions with detailed formulas in seconds.

Light Dark

Celsius to Fahrenheit

Convert temperature from Celsius (°C) to Fahrenheit (°F)

Temperature in Celsius (°C)

77°F

Formula: (25 × 9/5) + 32 = 77

25°C = 77°F = 298.15K

Fahrenheit to Celsius

Convert temperature from Fahrenheit (°F) to Celsius (°C)

Temperature in Fahrenheit (°F)

25°C

Formula: (77 - 32) × 5/9 = 25

77°F = 25°C = 298.15K

Kelvin Converter

Convert from Kelvin to Celsius and Fahrenheit

Temperature in Kelvin (K)

25°C / 77°F

298.15 K = 25°C = 77°F

Scientific absolute temperature scale

All Temperature Units

Enter any temperature and see all conversions

Enter Temperature

From Unit

Conversions

Celsius: 0°C

Fahrenheit: 32°F

Kelvin: 273.15K

Conversion History

Select conversion mode from Celsius, Fahrenheit, Kelvin, or All Units.

Enter temperature value in the input field.

Click Convert to see instant results with formulas.

View all conversions with detailed calculations.

Temperature Scales

Celsius (°C): Metric scale, water freezes at 0°C, boils at 100°C
Fahrenheit (°F): Imperial scale, water freezes at 32°F, boils at 212°F
Kelvin (K): Absolute scale, starts at absolute zero (-273.15°C)

Conversion Formulas

C to F: (°C × 9/5) + 32 = °F
F to C: (°F - 32) × 5/9 = °C
C to K: °C + 273.15 = K
K to C: K - 273.15 = °C
F to K: (°F - 32) × 5/9 + 273.15 = K

Common Temperatures

Water Freezing: 0°C = 32°F = 273.15K
Room Temperature: 20-25°C = 68-77°F
Body Temperature: 37°C = 98.6°F = 310.15K
Water Boiling: 100°C = 212°F = 373.15K

Select conversion mode from Celsius, Fahrenheit, Kelvin, or All Units.

Enter temperature value in the input field.

Click Convert to see instant results with formulas.

View all conversions with detailed calculations.

How to Use the Celsius to Fahrenheit Converter

Select Conversion Mode: Choose from Celsius to Fahrenheit, Fahrenheit to Celsius, Kelvin Converter, or All Units for simultaneous conversions.
Enter Temperature Value: Type the temperature you want to convert into the input field. The tool accepts decimal values for precise measurements.
Get Instant Results: Click the "Convert" button to see your results immediately with the conversion formula displayed.
View Complete Breakdown: See your temperature converted across all three scales (Celsius, Fahrenheit, and Kelvin) with detailed calculations.
Check Conversion History: Review your recent conversions in the history panel for quick reference during cooking, travel planning, or scientific work.

Understanding Temperature Conversion Formulas

Converting between temperature scales follows precise mathematical formulas. Understanding these formulas helps you verify results and grasp the relationship between different temperature systems.

Celsius to Fahrenheit:
°F = (°C × 9/5) + 32
Example: 25°C = (25 × 9/5) + 32 = 77°F

Fahrenheit to Celsius:
°C = (°F - 32) × 5/9
Example: 77°F = (77 - 32) × 5/9 = 25°C

Celsius to Kelvin:
K = °C + 273.15
Example: 25°C = 25 + 273.15 = 298.15K

Common Temperature Reference Points

These everyday temperature benchmarks help you understand what different readings mean in practical terms:

Temperature Point	Celsius (°C)	Fahrenheit (°F)	Kelvin (K)
Absolute Zero	-273.15°C	-459.67°F	0K
Water Freezing Point	0°C	32°F	273.15K
Room Temperature	20-22°C	68-72°F	293-295K
Human Body Temperature	37°C	98.6°F	310.15K
Water Boiling Point	100°C	212°F	373.15K
Comfortable Weather	18-24°C	64-75°F	291-297K

Practical Applications of Temperature Conversion

International Cooking & Baking: Follow recipes from different countries accurately by converting oven temperatures. European recipes typically use Celsius while American recipes use Fahrenheit.
Travel Planning: Understand weather forecasts when visiting countries that use different temperature scales. Pack appropriate clothing by knowing what 25°C or 77°F actually feels like.
Scientific Research: Convert laboratory measurements between scales, especially when working with international teams or publishing research globally.
HVAC and Climate Control: Set thermostats correctly when moving between countries or working with imported heating/cooling systems.
Medical Applications: Healthcare professionals often need to convert body temperatures between scales for international patient records or equipment calibrated in different units.
Engineering & Manufacturing: Industrial processes require precise temperature control, and specifications may come in different units depending on equipment origin.

Quick Mental Conversion Tip: To roughly convert Celsius to Fahrenheit in your head, double the Celsius temperature and add 30. For example, 20°C × 2 + 30 = 70°F (actual: 68°F). This gives a close approximation for everyday use!

Why Different Temperature Scales Exist

The existence of multiple temperature scales reflects historical scientific development and regional preferences:

Celsius (°C): Developed by Swedish astronomer Anders Celsius in 1742, this metric scale is used by most of the world. It's based on water's freezing (0°C) and boiling (100°C) points at standard atmospheric pressure, making it intuitive for everyday use.
Fahrenheit (°F): Created by German physicist Daniel Gabriel Fahrenheit in 1724, this scale is primarily used in the United States and a few Caribbean nations. It offers finer gradation for weather temperatures in temperate climates.
Kelvin (K): Named after Lord Kelvin (William Thomson), this absolute temperature scale starts at absolute zero, the theoretical point where molecular motion stops. It's the SI unit for temperature and essential in scientific work, particularly physics and chemistry.

Temperature Conversion in Daily Life

Understanding temperature conversion becomes crucial in many everyday scenarios. When cooking, many modern ovens display both Celsius and Fahrenheit, but older appliances or international recipes may only show one scale. A cake recipe calling for 180°C requires an oven set to 356°F (often rounded to 350°F).

Weather forecasting presents another common need for conversion. Travelers from the United States visiting Europe need to understand that 30°C represents a hot summer day (86°F), while 15°C is a cool autumn temperature (59°F). This knowledge helps with packing appropriate clothing and planning outdoor activities.

Healthcare Tip: Normal human body temperature is approximately 37°C or 98.6°F. A fever is generally considered to be 38°C (100.4°F) or higher. Keep these reference points in mind when monitoring health, especially when using thermometers from different regions.

Frequently Asked Questions

1. Why is 0°C equal to 32°F and not 0°F?

The two scales have different zero points. Celsius sets 0° at water's freezing point, while Fahrenheit originally set 0° at the lowest temperature achievable with a mixture of ice, water, and salt. This historical difference means 32°F equals the freezing point of pure water (0°C).

2. Is -40°C really the same as -40°F?

Yes! -40° is the unique temperature where Celsius and Fahrenheit scales intersect and show the same numerical value. You can verify this using the conversion formula: (-40 × 9/5) + 32 = -40.

3. When should I use Kelvin instead of Celsius or Fahrenheit?

Kelvin is primarily used in scientific contexts, particularly in physics, chemistry, and astronomy. Use Kelvin when working with absolute temperature measurements, gas laws, thermodynamic calculations, or any scientific work where negative temperatures would be meaningless. For everyday purposes, Celsius or Fahrenheit is more practical.

4. How accurate is this temperature converter?

Our converter uses standard mathematical formulas and provides results accurate to two decimal places, which is more than sufficient for all practical applications including cooking, weather interpretation, scientific calculations, and industrial use.

5. Can I convert negative temperatures?

Absolutely! The converter handles negative temperatures in both Celsius and Fahrenheit. However, note that Kelvin cannot be negative as it starts at absolute zero (0K = -273.15°C = -459.67°F), the theoretical lowest possible temperature in the universe.

6. Why do some countries still use Fahrenheit?

The United States, Belize, the Bahamas, the Cayman Islands, and Palau primarily use Fahrenheit. In the US, this is largely due to historical tradition and the significant cost of converting infrastructure, signage, and public education systems. Most scientific work in these countries still uses Celsius or Kelvin.

Note: This Temperature Converter performs all calculations locally in your browser. No temperature data is transmitted to external servers, ensuring your privacy. The tool is designed for educational, cooking, travel planning, and general reference purposes. For critical scientific or industrial applications requiring certified accuracy, please use calibrated laboratory equipment.