Conversions

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Conversions

Delisle to Celsius Calculator.

Converts a temperature from the Delisle scale to Celsius. The Delisle scale is an obsolete temperature scale where water boils at 0 °De and freezes at 150 °De.

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Your inputs

How it works

  1. 1

    Enter the temperature in degrees Delisle.

  2. 2

    Multiply the Delisle value by 2/3.

  3. 3

    Subtract that result from 100.

  4. 4

    The result is the temperature in degrees Celsius.

100 - delisle * 2 / 3

Frequently asked questions

What is the Delisle scale?

The Delisle scale (°De) is an obsolete temperature scale invented by Joseph-Nicolas Delisle in 1732. It is inverted: water boils at 0 °De and freezes at 150 °De.

How do I convert Celsius to Delisle?

Use the inverse formula: Delisle = (100 - Celsius) * 1.5. For example, 20 °C equals 120 °De.

Why is the Delisle scale inverted?

Delisle originally designed his thermometer with a glass tube that expanded when heated, so the scale was reversed. Later versions kept the inverted numbering.

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Temperature in Celsius

0°C

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How it works

Converts a temperature from the Delisle scale to Celsius. The Delisle scale is an obsolete temperature scale where water boils at 0 °De and freezes at 150 °De.

  1. Enter the temperature in degrees Delisle.
  2. Multiply the Delisle value by 2/3.
  3. Subtract that result from 100.
  4. The result is the temperature in degrees Celsius.

Formulas

The math behind this calculator, written out so you can verify the result.

Delisle to Celsius

°C = 100 - (°De × 2/3)

Since 150 °De corresponds to 0 °C and 0 °De to 100 °C, each degree Delisle equals 2/3 of a degree Celsius, and the scale is inverted.

Example:

Input: °De = 75

Calculation: 100 - (75 × 2/3) = 100 - 50

Result: 50 °C

Real-world use cases

Where this calculation shows up in everyday life.

Historical temperature records

Convert old temperature readings recorded in Delisle to modern Celsius for comparison.

Example: A 1730s record of 50 °De equals 66.67 °C.

Educational demonstrations

Teach about temperature scales and their historical development.

Example: Show that 0 °De is boiling and 150 °De is freezing.

Literature and science fiction

Interpret temperatures mentioned in historical texts or fictional works that use the Delisle scale.

Example: A novel mentioning 120 °De corresponds to 20 °C.

Tips and common mistakes

Tips

  • Remember the scale is inverted: higher Delisle means lower Celsius.
  • For quick mental conversion, subtract 2/3 of the Delisle value from 100.
  • Use the formula °C = 100 - (°De × 2/3) for precise results.
  • Check your result: 0 °De should be 100 °C, and 150 °De should be 0 °C.

Common Mistakes to Avoid

  • Forgetting the inversion and adding instead of subtracting.
  • Using 3/2 instead of 2/3 as the conversion factor.
  • Confusing Delisle with other obsolete scales like Réaumur or Rankine.

Assumptions and limitations

  • Use the stated inputs and units.
  • Results are estimates for planning and education.
  • Check measurements and source data before making an important decision.