We have a small in-house application which generates a string consisting of upper and lowercase letters, and the numbers 0-9. We've tried using various fonts to output this string, but users frequently get confused between certain combinations like:

  • Lowercase letter 'o' and uppercase letter 'O'
  • Uppercase letter 'O' and number '0'
  • Lowercase letter 'l' and number '1'
  • Uppercase letter 'S' and number '5'

and so on.

Can anyone recommend a font that might be suitable?

  • Can you give a little more detail on the end use of the font? Can it be a terminal-style font? Does it have to be pretty? Feb 27, 2018 at 16:13
  • It's only used internally so aesthetics don't matter. I tried fixed-width Courier, but uppercase 'O' looks too similar to the number zero.
    – Guesty
    Feb 27, 2018 at 17:29
  • 2
    Check if coding fonts provide the functionality that you are looking for. They are usually very careful in making all characters appear unambiguous. A "Slashed Zero", for example, is a common solution.
    – Jongware
    Feb 27, 2018 at 18:49
  • .v, (period vs comma), {}v() (curly brace vs parentheses) -- more confusions that a good font could resolve. This programmer with gradually waning eyesight would pay cashy money for a monospace font that did all this well.
    – Bob Stein
    Apr 12, 2021 at 16:28

3 Answers 3


I would suggest IBM Plex

It comes in 48 styles and the family includes both a sans-serif, a serif, and a monospaced variant, all with excellent distinctiveness (1/I/l and O/0 are easily distinguished and it has both dotted and slashed alternates available for zero), and the entire family is free.

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I'd suggest giving Courier Prime Code a whirl as the lowercase o is round while the uppercase O is more of an ellipse, and it has a slashed zero that's even more elliptical. The 1, i, j, I, J, 5 and S characters all have distinctive features as well. Best of all, it's free and Courier Prime (serif) and Courier Prime Sans are complementary typefaces (in case you need some variety).

https://quoteunquoteapps.com/courierprime/#code-sans Upper and lowercase plus numbers in Courier Prime Code


Many moons later I had the same need. The Windows font that worked for me was named "Consolas"

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