File size calculator
Choose image, sound or text, set the properties, and the calculator shows the formula, the substitution and every division from bits to bytes to kilobytes to megabytes.
File size questions are worth between two and five marks and are lost far more often to a missed conversion than to a missed formula. This calculator shows every division separately, so you can see exactly where an answer usually goes wrong.
File size calculator
Work out the size of an image, a sound file or a block of text, one conversion at a time. This tool needs JavaScript, so turn it on to use it. Everything you need to answer the exam question is explained in the text above.
The three formulas
| What | Formula | Watch out for |
|---|---|---|
| Image | width x height x colour depth | The answer is in bits, and metadata is extra |
| Sound | sample rate x bit depth x seconds x channels | Stereo doubles it, and minutes must become seconds |
| Text | number of characters x bits per character | Spaces and punctuation are characters too |
A lower case b means bits and an upper case B means bytes. Every one of these formulas gives you bits, so dividing by eight is always the first conversion.