Temperature Converter

The Three Temperature Scales

Celsius sets 0° at the freezing point of water and 100° at its boiling point, so its range is divided into 100 equal degrees. Fahrenheit places freezing at 32° and boiling at 212°, a 180-degree span, which makes each Fahrenheit degree smaller than a Celsius degree. Kelvin is the SI scientific scale: it uses Celsius-sized degrees but anchors 0 at absolute zero, the coldest temperature physically possible.

The Conversion Formulas

Because the scales have different zero points and different degree sizes, converting requires both a scale factor and an offset. Celsius to Fahrenheit is F = C × 9/5 + 32; the reverse is C = (F − 32) × 5/9. Kelvin is simpler because it shares the Celsius degree size: K = C + 273.15 and C = K − 273.15. To go straight from Fahrenheit to Kelvin, convert to Celsius first, then add 273.15.

Everyday Reference Points

A few anchors make conversions intuitive: water freezes at 0 °C / 32 °F, a comfortable room is around 21 °C / 70 °F, normal body temperature is 37 °C / 98.6 °F, and water boils at 100 °C / 212 °F. A hot summer day of 35 °C is 95 °F, while a cold −10 °C is 14 °F. Knowing these landmarks lets you sanity-check any converted value at a glance.

When Precision Matters

The +32 offset in the Fahrenheit formula is why doubling-and-adding-30 shortcuts drift as temperatures climb — fine for weather, risky for cooking or lab work. Baking, brewing, and medical readings depend on exact conversion: a 5° error near a candy-making threshold or a fever line can change the outcome. This tool applies the full formulas with decimals, so 37.5 °C correctly becomes 99.5 °F rather than a rounded estimate.