Temperature Converter

What this tool does

Temperature Converter translates readings between Celsius, Fahrenheit, Kelvin, Rankine and Réaumur using the exact defining formulas. It also converts temperature changes separately, because a difference of 10 degrees does not convert the same way as a reading of 10 degrees.

Unlike length or weight, temperature scales do not share a zero point, so you cannot convert them by multiplying alone. Fahrenheit sets water to freeze at 32 degrees and boil at 212, Celsius uses 0 and 100, and Kelvin starts at absolute zero. Weather forecasts, oven dials, lab reports and fever thermometers all mix these scales.

This tool applies the defining formulas: °F = °C × 9/5 + 32, K = °C + 273.15, °R = K × 9/5 and °Ré = °C × 4/5. Each reading is converted to kelvin and back, so every pair of scales is consistent. A separate panel handles temperature differences, where only the scale size matters: a rise of 1 °C equals a rise of 1.8 °F. All calculations run in your browser.

How to use Temperature Converter

1. Type the reading into the Value field, for example 37.
2. Pick the scale of your reading in From and the scale you want in To.
3. Read the Result, copy it, or swap the direction with the arrow button.
4. Check the all-units table for the same reading on every scale.
5. For a change in temperature rather than a reading, use the Temperature difference panel.
6. Paste several readings into Batch convert to convert a whole log or spreadsheet column.

Tips for better results

• For a rough Celsius to Fahrenheit estimate, double the number and add 30; for exact work use the result shown.
• Minus 40 is the one value that is the same in Celsius and Fahrenheit.
• Kelvin is written without a degree sign: 300 K, not 300 °K.
• Oven settings in older British recipes may be gas marks; gas mark 4 is about 180 °C or 350 °F.

Common use cases

• Understanding weather forecasts and fever readings from another country.
• Converting oven temperatures in imported recipes.
• Converting lab and engineering data between Celsius and kelvin.
• Converting thermostat or HVAC set-point changes between °C and °F.

Common mistakes to avoid

• Converting a temperature change with the reading formula, which wrongly adds or subtracts 32.
• Forgetting the 0.15 in 273.15 when precision matters in scientific calculations.
• Entering a value below absolute zero, such as −300 °C, which cannot exist.