I've recently started using BackBlaze as my backup service and I noticed something interesting on their restore sign-in page. The password input is slightly longer than their email input.

Sign in page for BackBlaze

Since this is their sign-in page and not their registration, I'm sure it doesn't have too much of an impact on determining a user's password length.

However, I contacted them about this and this was their response:

Looks like some goofy HTML to me! I just tried it a few places:

  • Safari Mac – normally equal sized boxes
  • Chrome Mac – same
  • Firefox Mac – Email field is longer
  • Firefox Windows – Password field is longer

Strange! I'll have to send it off to our designer. Thanks for the heads up. I'm curious if it would have some kind of effect on user passwords though as well!

So although it wasn't on purpose as I originally thought, it got me wondering: Does the size of an input matter beyond just its style? For example, Twitter's bootstrap input classes (mini, small, medium, large etc) if I were to use small for a new registration password instead of large or use large for an amount in a donation form instead of mini, can I help influence the user's input?

  • 1
    As a user, I do not like it when stuff I type is cut off because the input field is too short.
    – thgaskell
    Commented Feb 15, 2013 at 2:32

2 Answers 2


The size of the input field is absolutely a cue to the user about the expected input.

I've observed this in user testing and it has been demonstrated in formal research also, e.g. Denham, P. (2004) “The impact of space and survey format on open ended responses", published in Australasian Journal of Market & Social Research. Volume 12, No. 2, November 2004 (not available online). Denham found that the larger the box was, the more information people put it.

For this reason, I always advocate having fields that are proportional in size to the average (or acceptable) answer. So, BackBlaze would actually be better off having an email field that is larger than the password field (most passwords are smaller than email addresses). I talk more about the size of input fields on my website, if you're interested.

  • 2
    I don't agree that the email field should be longer. The email is a set length (you already have it) and presumably almost all emails fit into that box with no scrolling. Hinting that your password should be pretty long is never a bad thing however (of course it makes sense to do that on the registration page, not sign in).
    – Ben Brocka
    Commented Feb 15, 2013 at 4:22
  • I didn't say that the email field should be longer, just that it probably needs to be longer than the password field, as the latter is usually not much more than 6-10 characters. Remember, this form has to be designed to suit everybody's email addresses and passwords – the form doesn't know beforehand who is logging in. BTW, a longer password is not necessarily a stronger one. Commented Feb 16, 2013 at 4:29

This can be seen several different ways.

A user could feel that due to the length of the field that he is required to "fill it up" with characters in order to meet a minimum requirement.

A user could simply use a common password and think that the "person who built the form" is allowing him to add a more complex pass if wanted.

I've not seen any formal studies based on the length of a password field specifically that could give a definite answer either way to your hypothesis.

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