Temperature Converter

How the three scales are filled

The source is converted to Celsius first. Fahrenheit uses (value − 32) × 5/9. Kelvin uses value − 273.15. Celsius is copied through. From that Celsius figure the page builds Fahrenheit as Celsius × 9/5 + 32 and Kelvin as Celsius + 273.15. The source line is therefore included, and a clean input comes back unchanged: 100 °C prints Celsius (°C): 100, and 32 °F prints Fahrenheit (°F): 32. The formulas are the standard ones. There is no calibration offset and no choice of precision beyond the formatting below.

Each number is printed with up to four digits after the decimal, then trailing zeros are stripped, and a dangling decimal point is stripped with them. 100 stays 100. 212 stays 212. 373.15 keeps two places. 1 °C is 33.8 °F and 274.15 K. 37 °C is 98.6 °F and 310.15 K. 98.6 °F returns Celsius 37, Fahrenheit 98.6, and Kelvin 310.15. The binary value of 98.6 is not exact, but four-decimal rounding brings the Fahrenheit line back to 98.6. −40 °C prints Fahrenheit −40 and Kelvin 233.15.

The number box and the From menu

Temperature is a number input, so the browser's spinner and the minus key are available. The value is read with a floating-point parse. Enter in the box runs the same action as Convert. From lists Celsius (°C), Fahrenheit (°F), and Kelvin (K), and nothing else. The status starts at Ready to convert. Success says Converted successfully. Copy output copies the three labels and values. It does not copy the status line.

Please enter a valid number. appears when the parse is not a finite number. That includes an empty box. The previous Results stay on the page, and the copy buffer stays with them, because this failure returns before replacing the output. A later success replaces both. There is no live update while you type. If you change 100 to 0 and do not press Convert, the lines still describe 100.

Jobs for a Celsius, Fahrenheit, or Kelvin figure

Use the three lines when a recipe, a weather note, or a lab value arrives in one scale and the next reader wants another. 0 °C is the freezing point of water on this page: 32 °F and 273.15 K. 100 °C is the boiling point at standard pressure: 212 °F and 373.15 K. 0 K is absolute zero on the same formulas: −273.15 °C and −459.67 °F. The page will also convert −10 K or 5000 °C. It does not add a warning when the Kelvin line is negative.

Length, mass, volume, area, and digital sizes are the unit converter. That list has millimetres, kilograms, litres, acres, and bytes. It has no Celsius row, so a temperature typed there is not this conversion. A plain number that needs thousands separators, rather than a scale change, belongs on the number formatter. A Unix time is the timestamp converter, which does not speak Fahrenheit.

Rounding, absolute zero, and scales that are absent

Four decimal places is the cap. A value that needs more than four digits after the point is rounded by that formatting, then zeros are removed. You cannot ask for six places, for scientific notation, or for a fraction in the output. The source number itself may be a decimal. 0.5 °C prints as a half on the Celsius line and the converted lines follow the formulas before the same trimming.

Rankine, Réaumur, and Delisle are not in the From menu, and they are not derived in the result. There is no ΔT mode that would skip the 32-degree offset, so a temperature difference of 10 °C is still printed as a point on the scale: 50 °F and 283.15 K. If you meant a difference, subtract the Fahrenheit numbers yourself. The Kelvin label never carries a degree sign, even when the Celsius and Fahrenheit labels do. Copy output preserves that difference.

Rules and limitations

Source scales are Celsius, Fahrenheit, and Kelvin. Output order is always Celsius, Fahrenheit, Kelvin. Fahrenheit is (C × 9/5) + 32. Kelvin is C + 273.15. Printing keeps at most four decimal places and drops trailing zeros.

Empty or non-numeric input says Please enter a valid number. and keeps the previous lines. Negative Kelvin is allowed. Rankine is not offered. Copy output copies the three lines. There is no download and no live recalculation.

Common problems

If the lines still describe the previous number, Convert was not pressed after the edit. From changes behave the same way.

If you needed a difference of 10 degrees and the Fahrenheit line shows 50, the page converted a temperature of 10 °C, not an interval. Rankine will not appear if you type the word. The box only accepts a number.

Frequently asked questions

About this tool

Maintained by Toolbench. For large or deeply nested files, split the input into smaller batches and verify representative results before using them in an import or application. Report reproducible problems through Contact.