Unit and Format Conversions Without the Guesswork
Conversions are the kind of task where a mental estimate is usually close enough until the one time it is not. Recipes, shipping weights, travel distances, screen sizes, storage limits and engineering specs all move between unit systems, and each tool here does the arithmetic exactly rather than approximately. The result updates as you type, so you can feel how the two scales relate instead of converting one value at a time.
A note on data sizes, because this one causes real confusion: storage manufacturers count a gigabyte as a thousand million bytes, while operating systems traditionally count it as 1,073,741,824. That is why a drive sold as 500 GB shows up as roughly 465 GB once connected. The tool handles both conventions, and knowing which one you are looking at explains most apparent discrepancies in file and disk sizes.