What is the formula for Rømer to Celsius?

The formula is: °C = (°Rø − 7.5) × 40/21. For example, 18°Rø: (18 − 7.5) × 40/21 = 10.5 × 1.905 = 20°C.

What is 7.5°Rø in Celsius?

7.5°Rø equals exactly 0°C - the freezing point of water. Rømer set brine (saltwater) freezing at 0° and pure water freezing at 7.5°.

What is 60°Rø in Celsius?

60°Rø equals exactly 100°C - the boiling point of water. Rømer chose 60° for boiling as a round, highly divisible number.

Rømer to Celsius (°Rø to °C) Converter

1 °Rø = -12.381 °C

1 Rømer equals -12.381 Celsius (1 °Rø = -12.381 °C). Convert Rømer to Celsius with formula, table, and examples.

To convert Rømer to Celsius, subtract 7.5 and multiply by 40/21. Ole Rømer's scale (c. 1701) sets water's freezing point at 7.5°Rø and boiling at 60°Rø. This conversion is needed only for historical thermometry research.

How to Convert Rømer to Celsius

°C = (°Rø − 7.5) × 40/21

Formula: Rømer to Celsius

Subtract 7.5 from Rømer
Multiply by 40/21
Read the result in Celsius

Common Rømer to Celsius Conversions

Rømer (°Rø)	Celsius (°C)	Status
-10 °Rø	-33.33 °C
0 °Rø	-14.29 °C
5 °Rø	-4.76 °C
7.5 °Rø	0 °C
10 °Rø	4.76 °C
15 °Rø	14.29 °C
20 °Rø	23.81 °C
25 °Rø	33.33 °C
30 °Rø	42.86 °C
40 °Rø	61.9 °C
50 °Rø	80.95 °C
60 °Rø	100 °C
80 °Rø	138.1 °C
100 °Rø	176.19 °C
200 °Rø	366.67 °C

Good to Know About Rømer to Celsius Conversion

Rømer's scale is historically fascinating as the direct ancestor of Fahrenheit. The seemingly arbitrary numbers in Fahrenheit (32° freezing, 212° boiling) make much more sense when you realize they are Rømer's numbers multiplied by roughly 4.

Rømer to Celsius: What You Need to Know

Rømer body temperature (about 26.9°Rø) equals 37°C. Boiling water at 60°Rø equals 100°C. The Rømer scale's main importance is historical: Fahrenheit visited Rømer in 1708 and adapted his scale to create the Fahrenheit system still used in the US today.

What is a Rømer? °Rø

A temperature scale proposed by Ole Christensen Rømer in 1701. Water freezes at 7.5 °Rø and boils at 60 °Rø. It influenced Fahrenheit's scale development.

Historical historical history of science

Learn more about Rømer →

What is a Celsius? °C

A metric temperature scale where 0°C is the freezing point and 100°C is the boiling point of water. Used worldwide except in the US.

Metric weather cooking science

Learn more about Celsius →

Going the other way? Use our Celsius to Rømer converter.

Rømer to Celsius FAQ

The formula is: °C = (°Rø − 7.5) × 40/21. For example, 18°Rø: (18 − 7.5) × 40/21 = 10.5 × 1.905 = 20°C.
7.5°Rø equals exactly 0°C - the freezing point of water. Rømer set brine (saltwater) freezing at 0° and pure water freezing at 7.5°.
60°Rø equals exactly 100°C - the boiling point of water. Rømer chose 60° for boiling as a round, highly divisible number.

Non-Frequently Asked Questions About Rømer to Celsius

Questions nobody should ask - but someone did.

No. Ole Christensen Romer was a Danish astronomer who created his temperature scale around 1701. He is better known for being the first person to measure the speed of light. His temperature scale sets 0 at a brine freezing point and 60 at boiling water. Even geniuses sometimes make forgettable contributions alongside their masterpieces.