Same old story really; another client is requesting that they need x number of fields on their Contact Us form, and no amount of explaining that less=more will suffice without providing objective evidence. Does anyone have any links to studies that support (or even contradict) the hypothesis that reducing the number of fields increases conversion rates? Surely it's not just an assumption we all have that isn't based on any evidence?

I'm surprised there doesn't seem to be a similar post here about this but hopefully we can get some actual studies listed.

After most of the morning searching I have found one ( http://www.imagescape.com/clients-like-you/contact-form/ ) but I'm surprised there aren't more out there that I can find to back up this statement.

There is also this one about how Expedia saw a $12 million annual revenue increase by deleting ONE input field as linked to from this related ux.se question:

  • 6
    you shouldn't cherry pick your data. if you are doing this scientifically you need to look at any studies that contradict your hypothesis too, not just the ones that support it.
    – jk.
    Commented Apr 19, 2011 at 14:42
  • @jk - I don't understand what your comment has to do with the question in any way. Commented Apr 19, 2011 at 14:58
  • @JK, that's why I chose the word 'Hypothesis' rather than 'Fact' in the wording of the question, although granted I should probably amend it to 'Support / Contradict the Hypothesis'.
    – JonW
    Commented Apr 19, 2011 at 15:03
  • @charles if he's asking for evidence it should be representative of the published literature and not cherry picked. i understood the meaning, and agree with it, completely.
    – colmcq
    Commented May 2, 2012 at 14:28

4 Answers 4


Dan Zarella is frequently quoted by HubSpot and other Internet Marketers because of his careful study of Marketing Statistics. The second link has the most direct answers to what you are looking for:

  1. 3 Steps to Picking the Perfect Number of Landing Page Form Fields
  2. Which Types of of Form Fields Lower Landing Page Conversions (awesome)
  3. Landing Page Best Practices: Part II
  • 2
    Thanks, some great reading there. It's particularly interesting that they identify that it is not the number of fields but more the number of sophisiticated fields that does the most harm.
    – JonW
    Commented Apr 19, 2011 at 15:10
  • Billare - true enough thanks for changing those from hyperlinks to topic titles. Even though I look at UX, when I post something up quickly on a site like UX.Stackexchange - I think like an academic and like to show the source. I'll make sure to provide the source, and title as the link next time :) Commented Apr 24, 2011 at 18:47

According to Kevin Hale there is a correlation between the number of fields and convertion rate. But that's not all (as expected).

Number of fields. Site visitors are more likely to fill out shorter forms because they require less effort. The number of questions on a form correlates closely with the rate at which people drop off, Hale said: At five questions, the drop-off rate is 2 percent; at 10 questions, 4 percent, and so on. Only at about question 35 does the correlation end -- presumably because those who have stuck with the form that long are willing to stick it out to the end.

Quote from the article Increase online conversion rates


There's a company called Marketing Experiments that has done quite a bit of research into how you can manipulate a landing page to control the rate of conversion. I don't know how much of their content is available online (their conferences are not cheap - but they're very high quality), but you can get a feel for it at their website: http://www.meclabs.com/training/workshops/lpo/overview

While I realize that this won't provide you with an authoritative answer, perhaps it'll help (or at least point you in the right direction).

The summary of what they discussed is that the primary factors affecting the conversion rate are (in order of greatest to least):

  • The motivation of the user to buy the product
  • The clarity of the value proposition (ie, statement of the value they will receive by providing you with their email/name/credit card/etc)
  • The friction (ie, number of form fields) of the page, which is primarily offset by the incentives offered to continue (ie, free stuff)
  • Negatively, the anxiety of the user

So, while the number of fields on the form does play a pretty important role in affecting the rate of a conversion, it's not the only factor. If you do find that you need to have a lot of form fields, you can balance the "friction" by adding more incentive for the user to continue.

However, they did also mention a very interesting technique to help address the problem where too much friction reduces conversion quantity, whereas too little reduces the quality:

  • Split the form into two pages. On the first page, collect a small amount of information (name, phone number, email address).
  • On the second page, ask the user for the additional information you're looking for (answers to questions, physical location, etc)

Be sure to save the information collected from both pages in your database. That way, you have a list of quality leads (the people who completed both pages), but you also still get the high quantity leads (ie, the people who just completed the first page).

So, if your client is insisting on a large number of form fields, my recommendation would definitely be to split the form and move some of those questions to a later page in the process.

Also, my second suggestion to you would be to run tests on the form and see which one works better (ie, show the shorter version to half of your visitors and the long version to others and measure the conversion rates). There are some pretty nice tools available (Google's Website Optimizer is one) that'll allow you to do these types of experiments to conclusively determine what configuration of a page will result in the optimum rate of conversion (in terms of both quality and quantity).

(By the way, I would highly recommend the training course I mentioned above; they've invested a LOT of time into the marketing research process and the information they share with you is incredibly valuable).


Luke Wroblewski is a great resource for this type of data. He's done quite a bit of research and constantly is citing other relevant research in the industry.


He's a bit proponent of well designed forms, but an even bigger proponent of not having forms at all so has plenty of research to back that up.

(Though it's silly that we have to use 'hard data' to 'prove' this simple aspect of human nature: no one likes to do more work than they have to. ;)

In general, the big question is "Is this form useful for the user, or is it here just for the client?" Most of the time, the client is asking for all this data without even asking themselves if it's data they need.

  • 1
    More specifically this LukeW article seems to present actual evidence lukew.com/ff/entry.asp?910 but you need to actually look at the case study because the numbers are fairly small.
    – Elemental
    Commented Mar 13, 2015 at 12:42

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