I've often wondered this, but I haven't really sought an answer to it until now. Obviously, fonts do need to distinguish small "L" and capital "I" in some way and it does make sense to use letter height as a way to do so, but is there a reason why a lowercase "L" is chosen to be higher/longer than an uppercase "I"?

It just seems more logical to me that the capital letter be slightly higher.

I don't know that this is the case for all or most sans-serif or even serif (I noticed Times New Roman does the same thing), but for Calibri it definitely is. Interestingly, Arial seems to use the same height for "I" and "l".

1 Answer 1


The difference isn't anything specifically to do with a lower case "L" and capital "i", but all captials and ascenders. The short answer is they align to different metrics. There is a "Cap height" that all capital letters align to and an "ascender line" that ascenders align to.

You can see some basic font metrics, including the difference in cap and ascender heights in the typeface "Avenir" here:

enter image description here

The ascender height and cap height can be the same, often the ascender height is taller than the cap height but rarely (I can't think of any, but I won't say never) the other way around.

One reason is readability. Capital letters are generally all the same height and easy to distinguish from lower case letter so their height isn't an issue, the height of ascenders however can greatly affect readability, so they need to be taller—especially when there is a larger x-height—giving you more vertical variation.

It can also help in balance the visual weight of a typeface and is an important part of designing a typeface, from a purely visual perspective.

  • 1
    Thank you for your answer - I definitely learnt some new things! Though, I'm not sure whether you understood that I meant the capital letter I/i as your answer only seems to reference the letter "L". The font used by this site doesn't have serifs, so I understand why you were confused (if that is the case). But +1.
    – Dog Lover
    Nov 16, 2016 at 22:44
  • I always just thought it was done to differentiate between I and l (capital I and lowercase L)
    – Manly
    Nov 16, 2016 at 22:44
  • @DogLover I did understand you, I'm not sure why I said only the "L"... Long day, I'm tired :)
    – Cai
    Nov 16, 2016 at 22:48
  • @Manly it's certainly one of the benefits but it's not the only/main concern, there's definitely a lot more to it. There's probably a lot I havn't mentioned too but it's late and I'm tired :)
    – Cai
    Nov 16, 2016 at 22:51
  • @Cai I know those days! But I really commend you on providing such a great answer so quickly. I suppose it does make sense when I think of it in terms of ascenders.
    – Dog Lover
    Nov 16, 2016 at 22:51

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