Temperature is a numerical representation of the degree of hotness and coldness of a body or a particular entity. It is one of the most measured parameters; different scales developed to this effect over the years.

Today, the two most important scales for measuring temperature is the Celsius and the Fahrenheit scales.

The Fahrenheit Scale

This scale had its boiling point and freezing point of water placed at 212°F and 32°F respectively. It is used in the United States, the Bahamas, Cayman Islands, Palau, Belize and even alongside the Celsius scale in Canada.

Diagram explaining Fahrenheit and Celsius

Diagram explaining Fahrenheit and Celsius

The history of this scale is traced to a German scientist, Daniel Gabriel Fahrenheit. He lived and worked in the Netherlands.

Fahrenheit built the first modern thermometer in 1714, which was known as the mercury thermometer. This thermometer gave a better measurement of temperature than the previous gauges. The scale was designed as a sequel to a thermometer that uses alcohol. This was built by a Danish scientist known as Olaus Roemer. The device had only two calibrated points on it which are: 0° as the lowest point, 60° as the boiling point of water, 7.5° as the melting point of ice and body temperature was 22.5°.

Choosing Mercury

On usage, it became clear that the mercury thermometer gave more accurate values than the alcohol thermometer. Fahrenheit decided to stretch the Roemer scale by multiplying its values by four removing fractions and enhancing its granularity. He adjusted his range which initially had 30° and 90° as the melting point of ice and the body temperature.

After the calibration, the Fahrenheit scale now had 32° as the melting point of ice and 98.6° as the body temperature, while the boiling point of water became 212°. This gave him room to inscribe degree lines on his instrument by dividing each interval six times. This adjustment made after the adoption of freezing point and the boiling point as standard reference points for thermometer by the Royal society in 1776. These adjustments made the conversion of Fahrenheit to other scales quite easier and provided an accurate value for temperature measurement without fractions as it is used even until today.

Converting Fahrenheit

The Fahrenheit and Celsius scales have their meeting point at minus 40°F, such that minus 40°F and minus 40°C represents the same temperature. Below are some conversion formulas from the Fahrenheit scale to other scales;

  • Fahrenheit to Celsius: Subtract 32, then multiply by 5, then divide by 9
  • Kelvin to Fahrenheit: Subtract 273.15, multiply by 1.8, then add 32
  • Fahrenheit to Kelvin: Subtract 32, multiply by 5, divide by 9, then add 273.15
  • Celsius to Fahrenheit: Multiply by 9, divide by 5, and then add 32

The Celsius scale

The Celsius scale was the invention of an astronomer of Swedish origin, known as Andres Celsius in 1742. He was known as the first astronomer to give a detailed analysis of the fluctuations in the magnetic field of the earth and also designed apparatus to measure the intensity of light produced by the stars.

The Celsius scale had 0° and 100° representing the freezing point and boiling point of water respectively at standard atmospheric or barometric pressure at sea level.

Kelvin versus Celsius

Celsius vs Kelvin


Before this invention, Celsius painstakingly carried out lots of experiments, to ascertain if the freezing point of water is not influenced by the latitude coordinates or the atmospheric pressure of a particular place. These experiments were described in his published paper ‘Observations of two persistent degrees on a thermometer’. He later found out that latitude and atmospheric pressure affect the boiling point of water.

Since Celsius died in 1744, he was not alive to see his scale develop to world standards.one of the aftermath of his death was that the Celsius scale became inverted and even altered on some thermometers in the year 1747.

Initially, the Celsius scale was called centigrade; this was later changed in the year 1948. This is because there was a proliferation of units for measuring temperature, this prompted the Conference General des Poids et Measures to harmonize these units with the scales inclusive. However, ‘grade’ was a unit in use at that time, so to avoid confusion during measurement; Celsius was adopted to honor the legacy of the Swedish scientist.

Since then the Celsius scale gained continuous popularity as regards the measurement of temperature. The evidence of this popularity is evidenced by the switching over by nearly all countries to Celsius in 1970 in a bid to harmonize the metric measurement system.

Converting Fahrenheit

In the sciences, this scale is widely used as a Celsius degree has the same magnitude as degree Kelvin, another scale widely used by scientists. This makes it easy for scientists to work with these units and make calculations without any hassles. However, the following are conversion formulas from Celsius to other temperature scales;

  • Celsius to Fahrenheit: Multiply by 9, divide by 5, then add 32
  • Kelvin to Celsius: Add 273
  • Fahrenheit to Celsius: Subtract 32, then multiply by 5, then divide by 9
  • Celsius to Kelvin: Subtract 273

Though other scales existed as regards measuring temperature, these two scales have evolved with time finding application not just in the sciences but also used in the media during metrological reports as well as in other spheres.

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