We have a scenario where we require our users to enter in a six character hexadecimal serial number from an IOT device into a website textbox. Unfortunately, due to the form factor of the IOT device, the label that has the hexadecimal characters is only about 1'' wide by 3/4'' height. Also, this is a consumer device so our user base has no knowledge of what hexadecimal even is.

In our user studies and in the field we've seen a lot of users struggle with determining what character is on the label. This ultimately ends in us not being able to match up the device's events with the user and the user thinks the system is broken.

Is there a font that is best for the readability of hexadecimal characters, A-F & 0-9, at really small font sizes on a white label? Are there any other suggestions as to how we could make it more readable?

  • Are there limitations based on what system fonts are available? – Paul Redmond Jun 18 '15 at 14:22
  • Nope anything is game. – Zambonilli Jun 18 '15 at 14:33
  • While there is a strong usability angle here, I think the community over at graphicdesign.stackexchange.com tend to have much deeper experience and knowledge with font selection so I would recommend asking over there. – tohster Jun 18 '15 at 18:42
  • This is just too broad. There are dozens if not hundreds of valid suggestions. – DA01 Jun 18 '15 at 19:39
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    What can I do to make this more specific? I get there's a level of ambiguity on what the "best" solution is and it might become a subjective solution. However, it's a real problem with a statistically significant amount of our users not completing the task correctly. An ideal solution would be some sort of objective study with metrics on task completion of reading and writing 6 hex characters per font/font-size. However, this is the real world, so a consensus on a subjective solution or real world similar solutions is what I'm looking for. – Zambonilli Jun 18 '15 at 19:51

Here are some recommendations:

  • Monaco
  • Courier
  • Consolas

At smaller font sizes I would recommend turning anti-aliasing off for readability. Also, this is a good reference which shows the display of the fonts mentioned.

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  • I chose this solution because multiple people had references to the top 10 programming fonts link. Ultimately, we might end up doing a mechanical turk study on this to see if we get any conclusive differences in fonts/font-sizes but for now this is the best solution. Thank you. – Zambonilli Jul 6 '15 at 13:37

In general, when I go for sheer legibility and don't care about other font features, I go with Source Sans Pro. It's clear, compact and works great on any size, so it's pretty common choice for your kind of tasks

Another good choice is Droid, a font made after the Android font built by Ascender.

Take a look at both fonts with the characters you need (smaller size is 9 px)

enter image description here

Additionally, both fonts have serif versions should you need them

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I have a similar situation, small labels with 16 digits that must be human readable. What I have done is used a fixed width font (Courier), I've split the numbers into groups like #### #### #### #### and also set the spacing between the letters to be a little wider than default. This is pretty readable even at 9pt font - black on white or black on yellow.

Our labels come out of various printers for some printers we had to learn driver settings to make sure it would use the right thermal temp (hardware settings) or make sure it wouldn't do font substitutions (software setting)

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