What is the formula to convert Kelvin to Reaumur?

°Ré = (K − 273.15) × 4/5. Subtract 273.15 to get Celsius first, then multiply by 0.8.

What is the formula to convert Reaumur to Kelvin?

K = (°Ré × 5/4) + 273.15. Multiply the Reaumur value by 1.25 to get Celsius, then add 273.15.

What is absolute zero in Reaumur?

Absolute zero (0 K / −273.15°C) equals −218.52 °Ré on the Reaumur scale.

What are the freezing and boiling points of water in Reaumur?

Water freezes at 0 °Ré (273.15 K) and boils at 80 °Ré (373.15 K) at standard atmospheric pressure.

Why does the Reaumur scale go from 0 to 80?

René Antoine Ferchault de Réaumur defined his scale in 1730 with water freezing at 0 and boiling at 80, because the alcohol thermometer fluid he used expanded by 80 parts out of 1000 between those points.

Is the Reaumur scale still used today?

Rarely. It was once common in parts of Europe and Russia for food and brewing (cheese aging in France, for instance), but has been almost entirely replaced by Celsius.

Kelvin to Reaumur Converter

Enter a Kelvin value and instantly see its Reaumur (°Ré) equivalent, with the formula and a reference temperature table.

Temperature Converter

Kelvin (K)

Reaumur (°Ré)

°Ré

Reference Temperatures

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Description	K	°Ré

Summary

The Kelvin to Reaumur converter translates temperatures from the absolute Kelvin scale to the historical Reaumur scale (°Ré). The Reaumur scale, introduced in 1730, places water's freezing point at 0 °Ré and boiling point at 80 °Ré. The conversion formula is °Ré = (K − 273.15) × 4/5. Use the reference table to explore key scientific temperatures across both scales.

How it works

Enter a Kelvin value in the input field.
The tool subtracts 273.15 to convert Kelvin to Celsius.
It then multiplies the Celsius value by 4/5 (0.8) to get degrees Reaumur.
Reverse conversion works by multiplying °Ré by 5/4 and adding 273.15.
The reference table lists common temperatures in both K and °Ré for quick lookup.

Use cases

Understand historical thermometer readings recorded in the Reaumur scale.
Cross-check Kelvin values from scientific literature against the Reaumur scale.
Study the history of temperature measurement and the Reaumur scale's origin.
Convert cryogenic temperatures from Kelvin to Reaumur for historical reference.
Teach thermodynamics by comparing multiple temperature scales side by side.

Frequently Asked Questions

Last updated: 2026-07-14 · Reviewed by Nham Vu