Which takes up more disk space - images or text?

Answer: Even small images take up as much space as several pages of text. This is because each dot (or pixel) in the image has a certain value, which means there are lot of values to store. For example, a bitmap image that is 100 x 200 pixels in size must store 20,000 values. An image that is 640 x 480 must store 307,200 pixels.

Text documents, on the other hand, require a value for each character. Since each character takes up one byte of space, a page with 2,000 characters equals 2,000 bytes or about two kilobytes (2K). Compare that to a small 100 x 200 bitmap (.BMP) image, which takes up 124K.

Fortunately, JPEG and GIF compression can significantly reduce the file size of images. For example, the file above is reduced to 8K as a JPEG (with a compression ratio of 60%) and 12K as a GIF image. Still, it would take 4 pages of text to equal one small JPEG image and 6 pages or text to equal the same size GIF. If you're developing a website, it is important to realize that images will typically take up more space than the HTML.

Published: July 5, 2005   —   Updated: November 22, 2010 — by Per Christensson