Temperature Converter FREE

Convert temperature between Celsius, Fahrenheit, Kelvin and Rankine instantly online free. See conversion formula. No sign-up. Runs in your browser.

Celsius

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Kelvin

Rankine

Temperature Converter

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Frequently Asked Questions

The exact formula is F = (C x 9/5) + 32. For example, 100 degrees Celsius converts to (100 x 9/5) + 32 = 180 + 32 = 212 degrees Fahrenheit, which is the boiling point of water at sea level. The reverse formula is C = (F - 32) x 5/9.

Absolute zero is the lowest possible temperature, at which molecular motion stops. It is 0 Kelvin, which equals -273.15 degrees Celsius or -459.67 degrees Fahrenheit. The Kelvin scale starts at absolute zero and uses the same step size as Celsius, so 0 Celsius = 273.15 Kelvin.

The Rankine scale is an absolute temperature scale used in engineering applications in the United States. Like Kelvin, it starts at absolute zero. Unlike Kelvin, it uses Fahrenheit-sized degrees instead of Celsius-sized degrees. 0 Rankine = 0 Kelvin = -273.15 Celsius. Normal room temperature of 20 Celsius is approximately 527.67 Rankine.

Normal human body temperature is approximately 37 degrees Celsius, which equals 98.6 degrees Fahrenheit. This widely cited value is an average from a 19th century study. More recent research suggests normal body temperature ranges from 36.1 to 37.2 degrees Celsius (97 to 99 degrees Fahrenheit) depending on the individual and time of day.

The United States uses the Fahrenheit scale, which was introduced by Daniel Gabriel Fahrenheit in 1724. The United Kingdom and most of the world use the Celsius scale introduced by Anders Celsius in 1742 and later adopted by the International System of Units as the standard. The US is one of only three countries (alongside Liberia and Myanmar) that have not officially adopted the metric system.

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Free Temperature Converter Online — Celsius, Fahrenheit, Kelvin and Rankine

Temperature conversion is one of the most frequently needed calculations for cooking, weather forecasting, medical reference, scientific research, and international communication. The Temperature Converter on OneDocPDF converts between Celsius, Fahrenheit, Kelvin, and Rankine instantly. Unlike simple multiplication-based conversions for length or weight, temperature conversion requires applying the correct linear formula because each scale has a different zero point and different step size. This tool applies the exact conversion formula for every pair of scales and also shows all four scales simultaneously for any input value.

The Celsius scale is the international scientific and everyday standard used by most of the world, defined by the freezing point of water at 0 degrees and boiling point at 100 degrees at standard atmospheric pressure. Fahrenheit remains the primary scale in the United States for weather and everyday use, with freezing at 32 degrees and boiling at 212 degrees. The Kelvin scale is used in scientific and thermodynamic contexts because it starts at absolute zero and avoids negative values, making calculations involving the laws of thermodynamics cleaner and more intuitive. Rankine serves the same purpose as Kelvin but in the context of Fahrenheit-based engineering applications.

One Doc Studio provides a comprehensive library of free calculation and conversion tools. For broader measurement conversions across length, weight, area, and volume see our Unit Converter. For scientific and engineering calculations see our Scientific Calculator. For document and image processing tools see our full tool library.