- Enter Temperature — Type any temperature value into the input field. The tool accepts positive, negative, and decimal numbers.
- Select Units — Choose the source unit (From) and target unit (To) from five temperature scales: Celsius, Fahrenheit, Kelvin, Rankine, and Réaumur. Use the swap button to quickly reverse the direction.
- See Results — The conversion happens in real-time as you type. The main result is displayed prominently, along with the mathematical formula used for the conversion. All other unit conversions are shown simultaneously below.
- Copy Result — Click 'Copy' to copy the converted value to your clipboard for use in documents, spreadsheets, or other applications.
- Reference Points — Common temperature reference points (boiling point, body temperature, freezing point, absolute zero) are displayed at the bottom for quick reference.
Temperature Converter — Instant Conversion Between Temperature Scales
The Temperature Converter is a free, instant-use tool that converts between the five major temperature scales: Celsius, Fahrenheit, Kelvin, Rankine, and Réaumur. Unlike most online converters that only handle Celsius and Fahrenheit, this tool includes all historically and scientifically important temperature scales with real-time conversion, formula display, and a comprehensive reference points table.
All calculations are performed entirely in your browser using standard mathematical formulas. No data is sent to any server, making this tool suitable for scientific work, engineering calculations, educational purposes, and everyday temperature conversions.
Supported Temperature Scales
- Celsius (°C) — The most widely used temperature scale worldwide. Defined by the freezing point of water (0°C) and boiling point of water (100°C) at standard atmospheric pressure. Used in everyday life, weather forecasts, cooking, and most scientific contexts outside the USA.
- Fahrenheit (°F) — The primary temperature scale used in the United States and a few other countries. Water freezes at 32°F and boils at 212°F. Originally defined by Daniel Fahrenheit using a brine solution (0°F) and human body temperature (approximately 96°F).
- Kelvin (K) — The SI unit of temperature and the standard for scientific work worldwide. The Kelvin scale starts at absolute zero (0 K = −273.15°C) and uses the same degree size as Celsius. Kelvin does not use the degree symbol (°). Used extensively in physics, chemistry, astronomy, and engineering.
- Rankine (°R) — An absolute temperature scale using the same degree size as Fahrenheit but starting at absolute zero (0°R = −459.67°F). Used in some engineering disciplines, particularly in the United States for thermodynamic calculations involving Fahrenheit-based systems.
- Réaumur (°Ré) — A historical temperature scale where water freezes at 0°Ré and boils at 80°Ré. Once widely used in Europe, particularly in France and Germany, it has been largely replaced by Celsius but remains important for understanding historical scientific measurements and some traditional food processing standards.
Conversion Formulas
The key mathematical relationships between temperature scales:
- Celsius ↔ Fahrenheit — °F = °C × 9/5 + 32 | °C = (°F − 32) × 5/9
- Celsius ↔ Kelvin — K = °C + 273.15 | °C = K − 273.15
- Fahrenheit ↔ Kelvin — K = (°F − 32) × 5/9 + 273.15 | °F = (K − 273.15) × 9/5 + 32
- Celsius ↔ Rankine — °R = (°C + 273.15) × 9/5 | °C = (°R − 491.67) × 5/9
- Celsius ↔ Réaumur — °Ré = °C × 4/5 | °C = °Ré × 5/4
Key Features
- Real-Time Conversion — Results update instantly as you type, with no button clicks required. The responsive design makes conversions feel immediate and natural.
- Formula Display — Shows the mathematical formula used for each conversion, making this tool educational as well as practical. Great for students learning about temperature scales.
- All-Unit View — When you enter a value, all five temperature equivalents are displayed simultaneously. This gives you a complete picture without needing to switch between units.
- Swap Button — Quickly reverse the conversion direction with one click. Useful when you need to convert back and forth between scales.
- Reference Points — A quick-reference table shows common temperature landmarks: boiling point of water, average body temperature, freezing point of water, and absolute zero in multiple scales.
- Copy to Clipboard — Copy the converted result with a single click for pasting into documents, emails, or spreadsheets.
- Negative and Decimal Support — The converter handles negative temperatures (essential for Celsius and Fahrenheit) and decimal precision for accurate scientific conversions.
Common Use Cases
- Travel — Converting between Celsius and Fahrenheit when traveling between countries that use different temperature scales.
- Cooking — Converting oven temperatures between Celsius and Fahrenheit for international recipes.
- Science Education — Learning about different temperature scales and their relationships through formula display.
- Engineering — Converting between Kelvin, Rankine, and other scales for thermodynamic calculations.
- Weather — Understanding weather forecasts in unfamiliar temperature scales.
- Medical — Converting body temperature readings between Celsius and Fahrenheit.
Privacy and Browser Support
The Temperature Converter runs entirely in your browser. No data is transmitted to any server. Works in all modern browsers including Chrome, Firefox, Edge, Safari, and mobile browsers. No internet connection is required after the initial page load.