Temperature Converter
Convert between Celsius, Fahrenheit, Kelvin, Rankine, and Réaumur temperature scales. Quick and accurate temperature conversion for all your needs.
Result
0°C = 32°F
Complete Guide to Temperature Conversion
Temperature conversion is essential in countless daily activities, from cooking and weather forecasts to scientific research and engineering. Our free online temperature converter makes it easy to convert between Celsius, Fahrenheit, Kelvin, Rankine, and Réaumur instantly. Whether you're following an international recipe, traveling abroad, or working on scientific calculations, understanding how to convert temperature units accurately is crucial.
Understanding Temperature Scales
Temperature measures the degree of hotness or coldness of an object or environment. Different temperature scales were developed throughout history for various purposes, and today several scales remain in use worldwide. Each temperature scale has its own reference points and applications.
Common Temperature Scales
Celsius (°C) - Global Standard
Most widely used temperature scale worldwide. Water freezes at 0°C and boils at 100°C. Used for weather forecasts, everyday measurements, and most scientific applications. Room temperature ≈ 20-22°C, body temperature ≈ 37°C.
Fahrenheit (°F) - US Standard
Primarily used in the United States. Water freezes at 32°F and boils at 212°F. Smaller degree intervals make it more precise for weather without decimals. Body temperature = 98.6°F, room temperature ≈ 68-72°F.
Scientific Temperature Scales
Kelvin (K) - Absolute Scale
SI base unit for temperature. Starts at absolute zero (0 K = -273.15°C) where molecular motion stops. No degree symbol used. Water freezes at 273.15 K, boils at 373.15 K. Essential for physics, chemistry, and astronomy.
Rankine (°R) - Engineering Absolute
Absolute temperature scale using Fahrenheit-sized degrees. Used in some US engineering applications. Absolute zero = 0°R (-459.67°F), water freezes at 491.67°R.
Historical Temperature Scales
Réaumur (°r) - European Historical
Historical scale once used across Europe. Water freezes at 0°r and boils at 80°r. Now largely obsolete except in some historical contexts, old recipes, and specialized applications in Eastern Europe.
Key Reference Points
Water Reference Points:
- Freezing: 0°C = 32°F = 273.15 K = 491.67°R = 0°r
- Boiling: 100°C = 212°F = 373.15 K = 671.67°R = 80°r
Common Temperatures:
- Room: 20°C = 68°F = 293.15 K = 527.67°R = 16°r
- Body: 37°C = 98.6°F = 310.15 K = 558.27°R = 29.6°r
- Absolute Zero: -273.15°C = -459.67°F = 0 K = 0°R = -218.52°r
Temperature Conversion Formulas
Our temperature converter uses these precise formulas for accurate conversions:
Celsius to Fahrenheit:
°F = (°C × 9/5) + 32
Fahrenheit to Celsius:
°C = (°F - 32) × 5/9
Celsius to Kelvin:
K = °C + 273.15
Kelvin to Celsius:
°C = K - 273.15
Celsius to Rankine:
°R = (°C + 273.15) × 9/5
Celsius to Réaumur:
°r = °C × 4/5
Temperature Conversion Table
Quick reference for common temperatures across all scales:
| Reference Point | Celsius | Fahrenheit | Kelvin | Rankine | Réaumur |
|---|---|---|---|---|---|
| Absolute Zero | -273.15°C | -459.67°F | 0 K | 0°R | -218.52°r |
| Water Freezes | 0°C | 32°F | 273.15 K | 491.67°R | 0°r |
| Room Temperature | 20°C | 68°F | 293.15 K | 527.67°R | 16°r |
| Body Temperature | 37°C | 98.6°F | 310.15 K | 558.27°R | 29.6°r |
| Water Boils | 100°C | 212°F | 373.15 K | 671.67°R | 80°r |
Common Temperature Conversion Examples
Celsius to Fahrenheit Conversions:
- 0°C = 32°F (water freezes)
- 10°C = 50°F (cool weather)
- 20°C = 68°F (room temperature)
- 25°C = 77°F (warm weather)
- 30°C = 86°F (hot weather)
- 37°C = 98.6°F (body temperature)
- 40°C = 104°F (very hot weather/fever)
- 100°C = 212°F (water boils)
Fahrenheit to Celsius Conversions:
- 32°F = 0°C (water freezes)
- 50°F = 10°C (cool weather)
- 68°F = 20°C (room temperature)
- 70°F = 21.1°C (comfortable)
- 80°F = 26.7°C (warm weather)
- 90°F = 32.2°C (hot weather)
- 98.6°F = 37°C (body temperature)
- 212°F = 100°C (water boils)
Cooking Temperature Conversions:
- 180°C = 356°F (moderate oven)
- 200°C = 392°F (hot oven)
- 220°C = 428°F (very hot oven)
- 350°F = 177°C (moderate baking)
- 375°F = 191°C (medium-high)
- 400°F = 204°C (hot baking)
- 425°F = 218°C (very hot)
Kelvin Conversions:
- 0 K = -273.15°C = -459.67°F
- 273.15 K = 0°C = 32°F
- 293.15 K = 20°C = 68°F
- 310.15 K = 37°C = 98.6°F
- 373.15 K = 100°C = 212°F
Frequently Asked Questions (FAQ)
How do I convert Celsius to Fahrenheit?
To convert Celsius to Fahrenheit, multiply the Celsius temperature by 9/5 (or 1.8) and add 32. The formula is: °F = (°C × 9/5) + 32. For example, 25°C = (25 × 9/5) + 32 = 77°F. Our temperature converter calculates this instantly.
How do I convert Fahrenheit to Celsius?
To convert Fahrenheit to Celsius, subtract 32 from the Fahrenheit temperature and multiply by 5/9. The formula is: °C = (°F - 32) × 5/9. For example, 77°F = (77 - 32) × 5/9 = 25°C.
What is the difference between Celsius and Fahrenheit?
Celsius and Fahrenheit are two different temperature scales. In Celsius, water freezes at 0°C and boils at 100°C. In Fahrenheit, water freezes at 32°F and boils at 212°F. Celsius is used worldwide (metric system), while Fahrenheit is primarily used in the United States. The scales have different reference points and degree sizes.
What is Kelvin and how do I convert it?
Kelvin is the SI base unit for temperature and an absolute temperature scale starting at absolute zero (0 K = -273.15°C). To convert Celsius to Kelvin, add 273.15: K = °C + 273.15. To convert Kelvin to Celsius, subtract 273.15: °C = K - 273.15. Kelvin is used primarily in scientific applications.
What is absolute zero in different temperature scales?
Absolute zero is the lowest possible temperature where molecular motion stops. It equals: 0 Kelvin (K), -273.15°C (Celsius), -459.67°F (Fahrenheit), 0°R (Rankine), and -218.52°r (Réaumur). Nothing can be colder than absolute zero.
Which countries use Celsius vs Fahrenheit?
Most countries worldwide use Celsius (the metric system), including all of Europe, Asia, Africa, South America, and Australia. The United States, some Caribbean nations, and a few Pacific islands primarily use Fahrenheit. Canada uses both Celsius (official) and Fahrenheit informally.
What is normal body temperature in Celsius and Fahrenheit?
Normal human body temperature is approximately 37°C (Celsius) or 98.6°F (Fahrenheit). However, normal temperature can range from 36.1°C to 37.2°C (97°F to 99°F) depending on the person, time of day, and measurement method.
What are Rankine and Réaumur temperature scales?
Rankine (°R) is an absolute temperature scale like Kelvin but uses Fahrenheit-sized degrees. It's used in some US engineering applications. Réaumur (°r) is a historical scale where water freezes at 0°r and boils at 80°r. It was once used in Europe but is now obsolete except in some historical contexts and specialized applications.
How accurate is this temperature converter?
Our temperature converter uses precise mathematical formulas based on official conversion standards. Results are calculated with up to 4 decimal places and automatically formatted for optimal readability. All conversions follow internationally recognized temperature scale definitions.
Can I use this temperature converter for cooking?
Yes! This temperature converter is perfect for cooking and baking. Convert oven temperatures between Celsius and Fahrenheit, or use it to follow international recipes. Common cooking temperatures: 180°C = 356°F (moderate oven), 200°C = 392°F (hot oven), 220°C = 428°F (very hot oven).
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Tips for Temperature Conversion
- Quick Mental Math: For an approximate Celsius to Fahrenheit conversion, double the Celsius value and add 30. (Exact: multiply by 1.8 and add 32)
- Remember Key Values: Memorize common conversions like 0°C = 32°F, 100°C = 212°F, and body temp 37°C = 98.6°F
- Cooking Conversions: Most ovens have 25°F (about 15°C) variations, so round to nearest 25°F or 10°C for practical cooking
- Scientific Work: Always use Kelvin for thermodynamic calculations to avoid negative values and ensure proportional relationships
- Weather Interpretation: 0°C/32°F is freezing, 20°C/68°F is comfortable, 30°C/86°F is hot, 40°C/104°F is very hot