# Temperature Converter URL: https://speedycalculator.com/calculators/conversion/temperature-converter/ Last updated: 2026-10-25 > The temperature converter converts temperature between degrees Fahrenheit, kelvins, degrees Rankine, degrees Réaumur, degrees Delisle, degrees Newton and more. Choose any “from” and “to” unit, type a number into any field and every other unit updates instantly; all conversion factors are exact definitions. ## Inputs - From (°C, °F, K, °R, °Ré, °De, °N, °Rø) ## Results - To - Kelvins - Degrees Rankine - Degrees Réaumur - Degrees Delisle - Degrees Newton - Degrees Rømer ## Formula ``` °F = °C × 9/5 + 32 K = °C + 273.15 °R = (°C + 273.15) × 9/5 ``` ## Explanation Temperature scales differ in both their zero point and their step size, so converting means multiplying and adding an offset. Celsius and kelvin share the same step; Fahrenheit and Rankine use a step 5/9 as large. The converter also shows the historical Réaumur, Delisle, Newton and Rømer scales. ### How to use the Temperature Converter - Pick the unit you are starting from in the **From** menu and type your value. - Pick the unit you want in the **To** menu. The heading changes to match – for example “Degrees Celsius to Degrees Fahrenheit Converter”. - The most common temperature units are shown below at the same time, so you can compare them at a glance. - Type into any result to convert backwards, then use **Copy results** – the copied text starts with the heading for your chosen units. Results update as you type. Everything is calculated in your browser. ### How it works Every temperature unit is defined by an exact factor relative to the degree Celsius (the base unit). The calculator first turns the value you type into degrees Celsius, then turns that into the unit you picked in the “To” menu and into each of the common units below it. This two-step method means any unit can be converted to any other – 8 units are available in each menu – and you can type into any field, including a result, to work in the other direction. Changing a unit menu keeps the quantity the same and just re-expresses it, and the page heading and copied results follow your choice. ### How to convert temperature units - Choose the unit you have in the **From** menu and type the value. - Choose the unit you want in the **To** menu – the heading changes to match, for example “Degrees Celsius to Degrees Fahrenheit Converter”. - The calculator converts through the base scale using each unit's scale factor and zero offset. ### 1 degree Celsius in common units UnitValueDegrees Fahrenheit (°F)33.8Kelvins (K)274.15Degrees Rankine (°R)493.47Degrees Réaumur (°Ré)0.8Degrees Delisle (°De)148.5Degrees Newton (°N)0.33Degrees Rømer (°Rø)8.025 ### What is a degree Celsius? The Celsius scale sets 0 °C at the freezing point and 100 °C at the boiling point of water at sea level. Since 2019 it is defined from the kelvin: °C = K − 273.15. ### What is a degree Fahrenheit? The Fahrenheit scale, proposed by Daniel Fahrenheit in 1724, puts water’s freezing point at 32 °F and boiling point at 212 °F. It is the everyday scale in the United States. ### What is a kelvin? The kelvin is the SI unit of temperature. It starts at absolute zero, the coldest possible temperature, and has the same step size as the degree Celsius. ### Common mistakes to avoid Forgetting the offset (°f is not just °c × 1.8), converting temperature differences with the full formula (a change of 10 °c is a change of 18 °f, with no +32), and writing “degrees kelvin”. ### Good to know - Water freezes at 0 °C = 32 °F = 273.15 K and boils at 100 °C = 212 °F = 373.15 K at sea level. - Normal body temperature is about 37 °C = 98.6 °F. - The Delisle scale runs backwards: higher numbers mean colder. ## Worked example Inputs — From: 25 °C. Results — **To = 77 °F**; Kelvins = 298.15 K; Degrees Rankine = 536.67 °R; Degrees Réaumur = 20 °Ré; Degrees Delisle = 112.5 °De; Degrees Newton = 8.25 °N; Degrees Rømer = 20.625 °Rø. ## Key terms - **Absolute zero**: 0 K = −273.15 °C = −459.67 °F, the lowest possible temperature. - **Kelvin**: SI base unit of temperature with the same step as the degree Celsius. ## FAQ **At what temperature are °C and °F equal?** −40. **Why is there no degree sign on kelvin?** Kelvin is an absolute SI unit, written simply as K. **Can a temperature be below 0 K?** No. Absolute zero is the lowest possible temperature. **How do I change the units?** Pick any unit in the From and To menus. The value is converted in place, and the heading changes to show your conversion, for example “Degrees Celsius to Degrees Fahrenheit Converter”. **Can I type into any field?** Yes. Every field is editable, so you can start from whichever unit you have. **How many units can I convert between?** 8 temperature units, from the everyday to the specialised. **Which units are exact?** All factors here are exact by definition except astronomical and similar reference values, which use internationally agreed constants. **What formula does the Temperature Converter use?** °F = °C × 9/5 + 32. ## Sources - [NIST Special Publication 811 – Guide for the Use of the International System of Units](https://www.nist.gov/pml/special-publication-811) - [NIST Handbook 44 Appendix C – General tables of units of measurement](https://www.nist.gov/pml/owm/nist-handbook-44-current-edition)