Convert Electronvolt to Delisle
Convert electronvolts to degrees delisle instantly. °De = 559.725 − (eV × 17406.77718) — use the live calculator, the exact formula, a reference-temperature table and worked examples. Also check the Delisle to Electronvolt converter for the reverse conversion.
Units explained
Electronvolt
As a temperature unit, one electronvolt (eV) is the temperature at which a particle's characteristic thermal energy kT equals one electronvolt — exactly 11,604.51812 kelvins under the 2019 SI definitions of e and k.
Comes from the plasma-physics and astrophysics habit of quoting temperatures directly as energies through the Boltzmann relation E = kT, which removes constant unit conversions from the equations of hot ionized matter.
Standard in plasma physics, fusion research, and high-energy astrophysics: the core plasma of a tokamak runs at tens of kiloelectronvolts, while the Sun's core is about 1.3 keV.
Grew out of 20th-century particle- and plasma-physics convention; its kelvin equivalent became an exact number when the 2019 SI revision fixed both the elementary charge and the Boltzmann constant.
Delisle
The degree Delisle (°De) is a famously reversed scale: water boils at 0 °De and freezes at 150 °De, so numbers increase as temperature falls. One degree Delisle corresponds to exactly −2/3 of a kelvin.
Invented by French astronomer Joseph-Nicolas Delisle while directing the observatory in St. Petersburg, Russia; his thermometers were originally graduated by the contraction of mercury cooling down from the boiling point of water.
Widely used in 18th-century Russia for about a century. Today it appears only in the history of thermometry, where it is the textbook example of an inverted temperature scale.
Created by Joseph-Nicolas Delisle in St. Petersburg in 1732; recalibrated to the familiar 150-division form by Josias Weitbrecht in 1738.
Electronvolt to Delisle conversion formula
The exact relationship between electronvolts and degrees delisle:
To convert electronvolts to degrees delisle, multiply the value by 17406.77718 and subtract the result from 559.725. To reverse, multiply the value by 5.744889e-5 and subtract the result from 0.0321555791.
Reference anchors: water freezes at 0.0235382458 eV = 150 °De and boils at 0.0321555791 eV = 0 °De (at standard atmospheric pressure).
How to use this converter
Type a value into the calculator. The result in degrees delisle updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Delisle to Electronvolt converter for the reverse direction.
Step-by-step: convert electronvolts to degrees delisle
- Write down the temperature in electronvolts (eV).
- Multiply the value by 17406.77718 and subtract the result from 559.725.
- The result is the same temperature expressed in degrees delisle (°De).
- To reverse, multiply the value by 5.744889e-5 and subtract the result from 0.0321555791 — or open the Delisle to Electronvolt converter.
Worked examples
Example 1 — Convert 1 eV to °De:
559.725 − (1 × 17406.77718) = -16847.0521823251 °De
Example 2 — Convert 100 eV to °De:
559.725 − (100 × 17406.77718) = -1740117.9932325124 °De
Electronvolt to Delisle conversion table
Physically meaningful reference temperatures, from absolute zero to the surface of the Sun, converted from electronvolts to degrees delisle:
| Electronvolt [eV] | Delisle [°De] | Reference point |
|---|---|---|
| 0 | 559.725 | Absolute zero |
| 0.0200913125 | 210 | Where Celsius and Fahrenheit coincide (−40°) |
| 0.0220062754 | 176.6666666667 | Zero Fahrenheit (0 °F) |
| 0.0235382458 | 150 | Water freezes (0 °C / 32 °F) |
| 0.0235391075 | 149.985 | Triple point of water |
| 0.0243999791 | 135 | Cool day (10 °C / 50 °F) |
| 0.0252617125 | 120 | Room temperature (20 °C / 68 °F) |
| 0.0256925791 | 112.5 | Standard laboratory temperature (25 °C) |
| 0.0261234458 | 105 | Hot day (30 °C / 86 °F) |
| 0.0267266591 | 94.5 | Human body temperature (37 °C / 98.6 °F) |
| 0.0269851791 | 90 | Heat-wave day (40 °C / 104 °F) |
| 0.0278469124 | 75 | Hot tap water (50 °C / 122 °F) |
| 0.0321555791 | 0 | Water boils (100 °C / 212 °F) |
| 0.0390494457 | -120 | Moderate baking oven (180 °C / 356 °F) |
| 0.4979095159 | -8107.275 | Surface of the Sun (≈5,505 °C) |
Frequently asked questions
What is 1 eV in °De?
How do I convert electronvolts to degrees delisle?
How do I convert degrees delisle back to electronvolts?
At what temperature do the Electronvolt and Delisle scales read the same number?
Can a temperature be below absolute zero?
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Sources & references
Conversion relationship (°De = 559.725 − (eV × 17406.77718)) verified against the following authoritative sources:
- BIPM — The International System of Units (SI Brochure 9th ed.)
Official BIPM publication defining the seven SI base units (including the meter) and the rules for their use. The global authority on units of measurement.
- NIST — Guide to the SI
US National Institute of Standards and Technology reference covering the SI base and derived units with definitions and usage rules for US technical practice.
- NIST Special Publication 811 — Guide for the Use of the International System of Units
Detailed NIST guide covering exact conversion factors between SI and US customary units along with formatting and rounding conventions.
- BIPM — International Temperature Scale of 1990 (ITS-90)
The internationally agreed practical temperature scale, defining fixed points (including the triple point of water at 273.16 K) and interpolation instruments used by national metrology institutes for thermometer calibration worldwide.
- CODATA Internationally Recommended Values of the Fundamental Physical Constants
Committee on Data of the International Science Council; authoritative source for the masses of fundamental particles (electron, proton, neutron) and the atomic mass constant.