What's the formula for Celsius to Fahrenheit?

The formula is °F = (°C × 9/5) + 32. To convert Celsius to Fahrenheit, multiply the Celsius temperature by 1.8 (or 9/5) and add 32. For example, 0°C equals 32°F, 25°C equals 77°F, and 100°C equals 212°F. This formula works because the Fahrenheit scale has 180 degrees between water's freezing and boiling points, while Celsius has 100 degrees, creating a 9/5 ratio. The +32 accounts for the offset between the two scales' zero points.

How do I convert Fahrenheit to Celsius?

Use the formula °C = (°F - 32) × 5/9. First subtract 32 from the Fahrenheit temperature, then multiply by 5/9 (or 0.5556). For example: 32°F = 0°C, 98.6°F = 37°C (body temperature), and 212°F = 100°C (boiling point). Quick mental approximation: subtract 30 and divide by 2 for a rough estimate. So 80°F is approximately (80-30)/2 = 25°C (actual: 26.7°C). This is useful for quick conversions while traveling.

What is the Kelvin scale and when is it used?

Kelvin is the absolute temperature scale used in science, with 0 K representing absolute zero (-273.15°C), the coldest possible temperature where all molecular motion stops. Unlike Celsius and Fahrenheit, Kelvin has no negative values. Convert Celsius to Kelvin by adding 273.15 (K = °C + 273.15). Water freezes at 273.15 K and boils at 373.15 K. Kelvin is essential in physics, chemistry, astronomy, and engineering because equations involving temperature ratios only work correctly with absolute temperatures.

What are some common temperature references?

Water freezes at 0°C/32°F/273K, room temperature is 20-22°C/68-72°F/293-295K, body temperature is 37°C/98.6°F/310K, and water boils at 100°C/212°F/373K. Other useful references: hot summer day (35°C/95°F), comfortable bath (40°C/104°F), danger of heat stroke (>40°C/104°F), baking temperature (180°C/350°F), pizza oven (260°C/500°F), absolute zero (-273.15°C/-459.67°F/0K). These references help you quickly gauge if a converted temperature makes sense in real-world context.

Why does the US still use Fahrenheit?

The US, along with a few Caribbean nations, continues using Fahrenheit due to historical inertia and the massive cost of conversion. The Fahrenheit scale was established before US independence, and changing billions of signs, devices, and educational materials would cost billions of dollars. Some argue Fahrenheit offers more granular everyday measurements (0-100°F covers most weather conditions), while Celsius is more scientific. Most US STEM fields already use Celsius/Kelvin, but daily weather reports remain in Fahrenheit. Efforts to metricate the US in the 1970s had limited success.

At what temperature are Celsius and Fahrenheit equal?

Celsius and Fahrenheit show the same numerical value at -40 degrees (-40°C = -40°F). This unique intersection point occurs because of the mathematical relationship between the two scales. You can verify this: -40°C × 9/5 + 32 = -72 + 32 = -40°F. This is the only temperature where both scales read identically. At all other temperatures, they differ. This trivia is useful for checking your conversion formulas—if you get -40° in both scales, your math is working correctly. Temperatures below -40 become even colder in Fahrenheit values.

How do weather patterns differ between temperature scales?

Understanding weather in different scales: Celsius: below 0° is freezing, 10-15° is cool, 20-25° is comfortable, 30-35° is hot, 40°+ is extreme heat. Fahrenheit: 32°F is freezing, 50-60°F is cool, 68-77°F is comfortable, 86-95°F is hot, 104°F+ is extreme. The Celsius scale aligns with water's phase changes (0° freeze, 100° boil), making it intuitive for science. Fahrenheit's 0-100 range roughly matches human-livable temperatures in many climates, which some find practical. When traveling internationally, mentally convert: subtract 30 from Fahrenheit and halve for quick Celsius estimate.

Why is body temperature 98.6°F and not a round number?

Human body temperature is approximately 37°C, which converts to 98.6°F (37 × 9/5 + 32 = 98.6). The seemingly odd Fahrenheit value arises from converting the round Celsius measurement. Modern research shows normal body temperature varies (36.1-37.2°C or 97-99°F) depending on time of day, activity, age, and individual differences. The 98.6°F standard comes from 1800s German research that established 37°C as average. Recent studies suggest average body temperature has decreased slightly to about 98.2°F (36.8°C) over the past 150 years, possibly due to lower metabolic rates from less physical labor and better climate control.

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Temperature Converter

Convert temperature between Celsius, Fahrenheit, and Kelvin with common references

Temperature Converter

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What is Temperature Converter?

A temperature converter instantly translates between Celsius (°C), Fahrenheit (°F), and Kelvin (K) temperature scales used globally for weather, cooking, science, and everyday temperature measurements. Whether converting weather forecasts when traveling internationally, following recipes from different countries, working with scientific formulas, or understanding temperature specifications for equipment and materials, this calculator performs accurate bidirectional conversions accounting for the different zero points and degree sizes of each scale. Essential for international communication, travel, cooking, science students, and professionals working across different measurement systems.

Key Benefits & Use Cases

Understand weather forecasts when traveling internationally—know if 25°C is warm or cold (77°F, perfect weather), if 100°F is dangerously hot (38°C, yes), or if -10°C requires winter clothes (14°F, definitely). Follow international recipes accurately by converting cooking temperatures—350°F (common US baking temp) equals 175°C. Complete science homework and lab work by converting between Celsius for general use, Fahrenheit for some countries, and Kelvin for absolute temperature calculations in physics and chemistry. Understand product specifications and operating ranges for electronics, machinery, and materials that list temperatures in different scales. Save time and avoid calculation errors with instant, accurate conversions rather than manual formula applications.

How to Use This Calculator

Enter temperature value in your source scale (Celsius, Fahrenheit, or Kelvin) and results instantly display in all three scales simultaneously. For weather, Celsius is standard internationally except US (Fahrenheit). For cooking, convert between Fahrenheit (US recipes) and Celsius (everywhere else)—typical baking 350°F = 175°C, 400°F = 200°C, 425°F = 220°C. For science, Kelvin has absolute zero at 0K (-273.15°C or -459.67°F) with no negative values. Remember that Celsius and Fahrenheit scales cross at -40° (both read -40°). Quick reference: water freezes at 0°C/32°F/273K, boils at 100°C/212°F/373K, body temperature is 37°C/98.6°F/310K.