To convert a temperature from Celsius (°C) to the Rømer scale (°Rø), use this simple formula:
°Rø = \frac{21 \times °C + 300}{40}
This formula comes from the Rømer scale, where water freezes at 7.5°Rø (0°C) and boils at 60°Rø (100°C). Follow these steps for an easy calculation:
Example 1:Convert 20°C to Rømer.
21 × 20 = 420
420 + 300 = 720
720 ÷ 40 =18°Rø
Example 2:Convert 37°C (normal body temperature) to Rømer.
21 × 37 = 777
777 + 300 = 1,077
1,077 ÷ 40 =26.925°Rø(about 27°Rø)
Quick tip:For a rough estimate, multiply Celsius by 0.5 and add 7.5—it's close since 21/40 is about 0.525. But use the exact formula for precision!
DefinitionThe Celsius scale, also called centigrade, measures temperature using degrees marked as °C. On this scale, water freezes at 0°C and boils at 100°C under normal air pressure at sea level. This makes it easy to understand because it splits the range between freezing and boiling water into 100 equal parts.
History/OriginSwedish scientist Anders Celsius created this scale in 1742. At first, he set 100°C as the freezing point of water and 0°C as the boiling point, which was unusual. Scientists like Jean-Pierre Christin in France and Carl Linnaeus in Sweden soon flipped it to the version we use today. It replaced older scales and became popular in Europe during the 1700s.
Current UseCelsius is the standard temperature scale worldwide for science, weather reports, and cooking in most countries. It is the official unit in the International System of Units (SI). Only a few places, like the United States, still use Fahrenheit for everyday temperatures, but Celsius is taught everywhere in schools.
DefinitionThe Rømer scale measures temperature in degrees marked as °R. It sets the freezing point of water at 7.5°R and the boiling point at 60°R under normal pressure. The scale starts at 0°R, which is the freezing point of a salty ice mixture, colder than pure water ice.
History/OriginDanish astronomer Ole Rømer introduced this scale in 1701 to improve thermometer accuracy for his studies of Jupiter's moons. He divided the gap between the freezing of brine (salt water) at 0°R and boiling water at 60°R into 60 steps. It was one of the first practical temperature scales and was used mainly in Denmark and northern Europe until the 1800s.
Current UseThe Rømer scale is no longer used today. It was replaced by Celsius in the 19th century because Celsius was simpler and more consistent. You might see it mentioned in history books or old scientific texts, but modern thermometers do not use it anywhere.
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