Font for Access Key Code

I’m working on a project that will mail out access codes. Yes, using physical snail mail. The recipient needs to be able read the code and accurately type it into a web form. The codes consist of seven characters including upper case A-Z, lower case a-z, and digits 0-9.

My question is how to communicate exact characters, keeping in mind that I might have a number 0 immediately next to the letter O. A code may also contain one, but not the other. I’m also concerned about i vs I vs l vs 1… and those are four different valid characters.

What fonts can I use that will clearly distinguish these? What are tests I can use to check the font? Are there other sets of similar character glyphs I might be missing? Is there anything else that I can/should be doing to make sure these are readable in an accurate way?


Search for programming fonts.

Character differentiation can be crucial when programming; these are fonts that are designed specifically with this sort of thing in mind.

Consolas is a very popular choice. Here’s what those characters look like:


Here’s a huge thread on programming fonts over at Stack Overflow: Recommended Fonts for Programming?

I don’t want to change your criteria, but have you considered only distributing key codes that omit ambiguous characters? This is not an uncommon practice. For example, in the US all vehicles are required to have a VIN. As a measure of error prevention, they follow this rule:

does not include the letters I (i), O (o), or Q (q) (to avoid confusion with numerals 1 and 0)[1]

When the user inputs they key code, you could check for any of the invalid characters and have some sort of pop-up with a message like “Oops! You entered an I. Are you sure that’s not a 1?

Source : Link , Question Author : Joel Coehoorn , Answer Author : Community

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