What DPI should I scan text documents at?

Answer: the best DPI you can afford.

But the problem of using more Dots Per Inch, is the more DPI you use, the more space it’ll take up on your hard drive.

I scan colour A4 documents at 150dpi, but that means an average output size of approx. 300kb.

So, I thought, let’s measure the scan quality for DPI settings of 200, 150, 100, 75 & 50.

The test document
Printout of a string of characters in the Times New Roman font from 4 point to 12 point.

The results:
50 DPI – Even the 12 point is getting close to unreadable.

75 DPI – 10 point is readable, 8 point is a bit blurry.

100 DPI – 8 point is much better.

150 DPI – 4 point is just readable.

200 DPI – 4 point is readable.

So in summary