Units of data storage

All data in a computer (text, images, sound, etc.) must be stored in binary (0s and 1s). Computers only understand on (1) and off (0) signals using electronic circuits.
Increments of storage space go up in a geometric sequence (same multiplier), in this case ×2 (i.e. 1, 2, 4, 8, 16, 32…).
File size calculations: to determine how much storage a file will need:
- Text file size = bits per character × number of characters. There are usually 8 bits (1 byte) per character (ASCII).
- Image file size = colour depth × image width × image height. This is measured in bits. Colour depth = bits per pixel.
- Sound file size = sample rate × bit depth × duration (seconds), often multiplied by the number of channels (e.g. 2 for stereo).

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