Data capacity and calculation of data capacity requirements

1.2.3 Units

Units — Note 3 of 3

What you need to know

Calculating data capacity involves determining how much storage space is needed for files. You need to know the formulas for calculating sound, image, and text file sizes, and be able to convert between units.

What to know

Sound file size = sample rate × duration × bit depth.
Image file size = colour depth × image height × image width (pixels).
Text file size = bits per character × number of characters.

Exam technique

Tip:Always check the UNITS required in the answer — you may need to convert from bits to bytes (divide by 8) or between KB, MB, GB.
Tip:Show your working clearly in calculation questions — even if the final answer is wrong, you can score method marks.
Mistake:Forgetting to include ALL characters in a text file size calculation, including spaces and punctuation.

Ready to test yourself?

Practise 1.2.3 questions

← Previous noteHow data needs to be converted into a binary format to be processed by a computer1.2.3 Units Next topic →How to convert positive denary whole numbers to binary numbers (up to and including 8 bits) and vice versa1.2.4a Data Storage: Numbers

Back to Units

Revise another OCR GCSE topic: Data Storage: Numbers