Temperature Converter

The Celsius scale (°C) was developed in 1742 by the Swedish astronomer Anders Celsius and is the standard unit for everyday temperatures in Germany, Europe and most countries around the world. The freezing point of water is 0 °C, and the boiling point is 100 °C (at standard pressure of 1,013.25 hPa). Celsius originally defined the scale the other way round: boiling point = 0 °C, freezing point = 100 °C. It was his colleague Carl Linnaeus who reversed the scale into the form we know today.

The Fahrenheit scale (°F) was invented in 1724 by the German physicist Daniel Gabriel Fahrenheit. Fahrenheit chose as his zero point the coldest temperature he could measure in the winter of 1708/09 in Danzig (a freezing mixture of water, ice and ammonium chloride). As a second fixed point, he chose the body temperature of a healthy person (today: 98.6 °F). Fahrenheit is now used mainly in the US and a few Caribbean countries. The freezing point of water is 32 °F, and the boiling point is 212 °F. The scale has 180 divisions between these points (compared to 100 for Celsius), which is why one Fahrenheit degree is smaller than one Celsius degree: 1 °F ≈ 0.556 °C.

Kelvin (K) is the SI unit of thermodynamic temperature, named after the British physicist William Thomson (Lord Kelvin). Its zero point (0 K = −273.15 °C) corresponds to absolute zero, where all thermal motion comes to a stop – theoretically unreachable according to the third law of thermodynamics. Unlike Celsius and Fahrenheit, Kelvin has no degree sign. Kelvin is used in science and technology: from quantum physics to color temperature in photography (6,500 K corresponds to daylight, 3,000 K to incandescent bulbs).

In everyday medical use, the Celsius-Fahrenheit conversion is especially important: a normal body temperature of 37 °C corresponds to 98.6 °F. From 38 °C (100.4 °F), an elevated temperature is considered a fever. Anyone reading American medication package inserts or health apps will come across Fahrenheit figures that need to be converted correctly. Recipes from the US differ in the same way when it comes to cooking: an oven temperature of 350 °F corresponds to about 175 °C, which matches the "conventional heat 175 °C" or "fan oven 160 °C" setting on German ovens.

A handy rule of thumb for quick Celsius-to-Fahrenheit estimates: doubling the Celsius value and adding 30 gives a good approximation (e.g. 20 °C → 20 × 2 + 30 = 70 °F, exact value: 68 °F). For the reverse direction: subtract 30 from the Fahrenheit value, then halve it (e.g. 70 °F → (70 − 30) ÷ 2 = 20 °C, exact value: 21.1 °C). This rule of thumb works well for everyday estimates, but our converter gives you the exact values.