I am currently optimising an e-commerce website. The request was specific to the product pages, after gaining insight from analytics and feedback two alternatives were proposed, and tested.

The add-to-cart rate increase by 3% (roughly) with both options, but the overall conversion rate decreased by 1%, any idea why this happens?

No changed were made in other pages, only to the product page.


  • 3
    How are you calculating conversion rate? Could it be affected by the add to cart rate, or is it truly based on number of visitors completing a purchase? eg you've made it easier for people to get further in the process, but most of those who are not going to buy are still not going to buy. Say beforehand you have 200 visitors - 100 of them add to cart and 50 of those complete purchase. Afterwards 103 of them add to cart and 51 of those complete purchase. Your add to cart rate has gone up by 3% (from 100 to 103) but the number of carts that complete purchase (51 of 103) has gone down by 0.5% Commented Sep 14, 2011 at 9:52
  • The conversion rate is calculated on the number of users in the group. So in your example I would calculate the first conversion rate as 25%, and the second as 25.5%
    – Davide
    Commented Sep 14, 2011 at 10:09
  • Just to report my similar experience. Months ago I changed the add-to-cart button label from "order" to "add to cart". That was the only change. In the following two weeks the add-to-cart rate increased, but the overall conversion rate decreased (-4%). Commented May 17, 2014 at 8:37

2 Answers 2


A few possibilities that I can see:

  1. Your measurement is not against the same baseline - the changes may have drawn in a few more people to the core pages, but they are browsers not purchasers - adding to the cart may be a way of noting products. As @Roger implied, you may be getting more purchases, but a slightly lower conversion rate, which is not really an issue.

  2. Your improvements to the product pages may be excellent, and drawing people in to look, but they are put off when the changes* are not continuing to be reflected in the checkout.

Having said that, you need to continue to monitor and assess,, see if you can identify exactly where people are dropping out, which may give you some more clues. But the reality is that you may have look at some of the changes you have made and ensure that they are reflected through the checkout process.

  • Bear in mind that the changes to the user experience may not always be the immediate and obvious stuff. If look and feel change once you have added to the basket this can be a big issue, as it feels suddenly worse, just when you are after peoples money.
  • That's what I thought, we just moved the bottleneck down the funnel... thanks
    – Davide
    Commented Sep 14, 2011 at 10:20
  • You probably improved things - don't dismiss it completely! - for those who were put off by the product pages. But it needs at some point to be progressed. You now have proof that it makes a difference. Commented Sep 14, 2011 at 10:28

You don't have to worry I think. In my opinion 1% change is really nothing. Conversion rates usually fluctuate, just like everything else. I wouldn't consider 1-2% a real change.

If you examine longer time periods (months) and compare them to each other, 1-2% can be considered a real change. But in some days you shouldn't worry about 1% drop in conversion rate.

  • 1
    The test ran for 6 days with 50.000 in the control group and 50.000 in each option's group, and of course where simultaneous. This would lead me to think that is significative of a comparison between the designs.
    – Davide
    Commented Sep 14, 2011 at 9:25
  • any way you can post wireframes of the changes you made and the prior states of the designs? I suspect you've made the add to cart calls to action more obvious in some way but not improved the check out calls to action....just a hunch
    – colmcq
    Commented Sep 14, 2011 at 9:38
  • The wireframe are confidential (nothing special really but..) and yes we did not touch the checkout pages.
    – Davide
    Commented Sep 14, 2011 at 10:11
  • so are you saying that you've changed the interaction of the add to cart functionality but not the checkout?
    – colmcq
    Commented Sep 14, 2011 at 10:21

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