Temperature Converter

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Common reference points

How it works

Celsius and Fahrenheit are related by a scale factor and an offset: °F = °C × 9/5 + 32, and back again with °C = (°F − 32) × 5/9. The 9/5 is because a Fahrenheit degree is smaller — 180 Fahrenheit degrees span the same gap as 100 Celsius degrees between freezing and boiling water. Kelvin uses exactly the same degree size as Celsius and simply starts at absolute zero instead: K = °C + 273.15. No multiplying, and no degree symbol — a Kelvin temperature is just written 310.15 K.

Absolute zero is the floor of temperature itself: -273.15 °C, -459.67 °F, 0 K. Nothing can be colder, so entries below it are refused here rather than converted. The scales meet at one famous point: -40 is the same temperature in both °F and °C — a handy check for any conversion.

Worked example: body temperature, 98.6 °F. Celsius: (98.6 − 32) × 5/9 = 66.6 × 5/9 = 37 °C. Kelvin: 37 + 273.15 = 310.15 K.

Frequently asked questions

What is 350 °F in Celsius (for an oven recipe)? (350 − 32) × 5/9 = 176.7 °C — most recipes round that to 175 °C or 180 °C, and ovens are not precise enough for the difference to matter.

Why does Kelvin have no degree symbol? Kelvin is the SI base unit of temperature, treated like meters or seconds — a quantity, not a scale of degrees. It is written K, never °K.

Quick estimate without a calculator? For weather temperatures, double the Celsius and add 30 for a rough Fahrenheit (20 °C → about 70 °F, true value 68 °F). Close enough to decide on a jacket — the exact conversion is above.