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    How to Convert Celsius, Fahrenheit & Kelvin

    UnitConvertLab Team
    2026-01-04
    5 min read

    Understanding Temperature Scales

    Temperature is one of the most commonly converted measurements, yet it's also one of the trickiest because it doesn't use simple multiplication like other unit conversions.

    The Three Main Scales

    Celsius (°C)

    • Freezing point of water: 0°C
    • Boiling point of water: 100°C
    • Used by: Most of the world
    • Best for: Daily weather, cooking, science

    Fahrenheit (°F)

    • Freezing point of water: 32°F
    • Boiling point of water: 212°F
    • Used by: United States, some Caribbean nations
    • Best for: Weather in the US, some cooking

    Kelvin (K)

    • Absolute zero: 0 K (-273.15°C)
    • Freezing point of water: 273.15 K
    • Used by: Scientists worldwide
    • Best for: Scientific calculations, physics

    Conversion Formulas

    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

    Quick Reference Points

    DescriptionCelsiusFahrenheitKelvin
    Absolute zero-273.15-459.670
    Water freezes032273.15
    Room temperature20-2268-72293-295
    Body temperature3798.6310.15
    Water boils100212373.15

    Practical Examples

    Example 1: Convert 25°C to Fahrenheit

    °F = (25 × 9/5) + 32 = 45 + 32 = 77°F

    Example 2: Convert 98.6°F to Celsius

    °C = (98.6 - 32) × 5/9 = 66.6 × 5/9 = 37°C

    Key Takeaways

    • Temperature conversions require formulas, not simple multiplication
    • Celsius and Kelvin differ by exactly 273.15
    • Fahrenheit uses a different scale entirely
    • Room temperature is about 20°C, 68°F, or 293K