Calculations

• Calculation for Text Files

  (Bytes per character) x (Number of characters)

  e.g. 'hello word' text file size using Extended ASCII

  1 byte per character (due to use of 8-bit Extended ASCII)

  10 characters (including spaces)

  1 x 10 = 10 bytes

  If greater then change Units e.g. 2000bytes into 2KB
• Calculation for Image Files


  (Resolution) x (Colour Depth)

  
  

  e.g. Image with 500 width and 500 height and 24 bits colour depth

  Resolution = 500 x 500 = 250000

  colour depth = 24

  250000 x 24 = 6000000 bits

  bits to bytes = 6000000 divided by 8 = 750,000 bytes

  bytes to Kilobytes 750,000 bytes divided by 1000 = 750 Kilobytes
• Resolution Calculation

  Width x height
• Sound Files

  (Sample Rate) x (Duration in seconds) x (Bit Depth)

  
  

  e.g. Sound recording of 10 samples per second for 30 seconds was taken with 4 bits stored per sample

  Sample rate = 10

  Duration = 30

  Bit Depth = 4

  10 x 30 x 4 = 1200 bits

  1200 divided by 8 = 150 bytes
• total number of colours

  2^n (where n is number of bits per pixel)