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Knowledge organisers / Data Storage: Characters

Calculate file sizes of text

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Knowledge organiser

Data Storage: Characters

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What you need to know

The file size of a text file can be calculated using the formula: text file size = bits per character × number of characters. You may need to convert the result between units (bits, bytes, KB, etc.).

Key points

  • Text file size = bits per character × number of characters.
  • Remember to count ALL characters including spaces and punctuation.
  • To convert bits to bytes, divide by 8.
  • Exam Tip:Check carefully whether the question gives bits per character or bytes per character — this affects your calculation.
  • Example: 'Hello World' encoded in ASCII (8 bits per character) = 11 characters × 8 bits = 88 bits = 11 bytes.