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Temperature Converter

Convert air, oven, or science temperatures between Celsius, Fahrenheit, and Kelvin using the standard linear relationships.

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Result

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The formula

All conversions route through Celsius: Fahrenheit uses the 9/5 scale with a 32° offset; Kelvin shifts Celsius by 273.15 (absolute zero).

°F = °C × 9/5 + 32 · °C = (°F − 32) × 5/9 · K = °C + 273.15

Worked example

  1. 25 °C → Fahrenheit
  2. 25 × 9/5 = 45; 45 + 32 = 77
  3. Kelvin: 25 + 273.15 = 298.15 K

Result: 77 °F · 298.15 K

How temperature scales convert

Celsius and Kelvin share degree size; Fahrenheit degrees are smaller (1 °C = 1.8 °F). Only the zero points differ.

Via Celsius

We convert the input to Celsius, then to the target scale. That keeps a single implementation path for C ↔ F ↔ K.

Fixed points

At standard atmospheric pressure, water freezes near 0 °C / 32 °F and boils near 100 °C / 212 °F. Absolute zero is 0 K = −273.15 °C — Kelvin cannot go below zero.

What we do not model

No Rankine, Réaumur, or wet-bulb conversions. Boiling point shifts with altitude are ignored — this is pure scale math.

Interesting facts

Water marks

At sea level, water freezes at 0 °C / 32 °F and boils at 100 °C / 212 °F — handy anchors for any conversion.

Kelvin

Kelvin is absolute; 0 K is absolute zero (−273.15 °C). Scientists prefer kelvin because it starts at a true physical zero.

Size of a degree

One Celsius degree and one kelvin step are the same size. Fahrenheit degrees are smaller: 1 °C = 1.8 °F.

Body temperature myths

“Normal” human temperature is often cited as 37 °C / 98.6 °F, but healthy readings span a range across time of day and method.

Weather vs cooking

Meteorology leans Celsius worldwide; many US kitchens still think in Fahrenheit for ovens and candy thermometers.

Frequently asked questions

Multiply by 9/5 and add 32. Example: 25 × 1.8 + 32 = 77 °F.

Subtract 32, then multiply by 5/9. Example: (77 − 32) × 5/9 = 25 °C.

Often cited around 20–22 °C (68–72 °F), depending on climate and preference.

No — 0 K is absolute zero. Negative Celsius or Fahrenheit values are fine and convert normally.

No. 0 °C = 273.15 K. 0 K is −273.15 °C.

References

  1. SI temperature unit — kelvin — National Institute of Standards and Technology (NIST) Kelvin is the SI base unit of thermodynamic temperature.
  2. BIPM — SI Brochure — Bureau International des Poids et Mesures International definition of the kelvin and related SI units.
  3. NWS temperature resources — U.S. National Weather Service Operational weather temperatures; pairs well with wind chill and heat index tools.