How to Run an A/B Test


A/B testing (or 'Split Testing') is a fantastic way to experiment with new ideas and test variations ('variants') of your landing pages, pop-ups, or sticky bars.

This article will explain:

What is an A/B Test?

A/B testing is a simultaneous experiment between two or more variants of your landing page to see which one performs the best, whether that be more page views or more conversions.

Some of your page visitors will land on one variant of your landing page, and the others on another variant. 

How to Start an A/B Test in Unbounce

Select a page you would like to test to reach the Page Overview screen.

Scrolling down the Page Overview screen, you will see options to change the Page Traffic Mode.

Gif demonstrating how to change page traffic mode

Standard Mode is used when you only have a single variant running - no kind of testing is currently underway.

In contrast, Smart Traffic is Unbounce's AI-driven page testing mode that uses machine learning to drive traffic to the variant it feels your visitor is most likely to convert on. Learn more about Smart Traffic here within our documentation: What is Smart Traffic?

And then finally, we have A/B Test Mode, which is what this article will walk through.


Smart Traffic is only available on the Optimize 2024 plan, as well as all 2020 legacy plans.

Should I use Smart Traffic or A/B Testing?

Whereas with A/B testing you can set a specific percentile between your page variants, Smart Traffic handles all of that for you. It considers several other variables to determine which variant it believes your visitor is most likely to convert on.

See our documentation for more information on Smart Traffic and why you should consider using it: Getting Started with Smart Traffic.

Creating Multiple Variants

Once you've selected A/B Test Mode, you can then proceed to add a new variant. You can choose to either 1) duplicate an existing variant as a starting point for your experiment, or 2) you can create a new variant from scratch or use an Unbounce template.

Duplicating an Existing Variant

  1. Click the ellipses (three dots) to the right of the variant within the Page Overview.
  2. From the drop-down menu, select Duplicate
    Annotated image of a page overview showing how to duplicate a variant

Creating a New Variant from Scratch or With an Unbounce Template

  1. Scroll down to the bottom of the Page Overview, and click the Add Variant button.
  2. You will see a prompt to create a new variant from scratch (a blank page) or a template.

Duplicating an existing variant is a quick and easy way to test subtle or more moderate changes to your page design - such as different copy, placement of images, or colors.

On the other hand, using a new variant from scratch or a template may be a better choice if you want to test two completely different concepts against one another.

Setting Variant Weights

If you're starting an A/B for the first time, it would be best to start with two variants at 50/50 traffic weights each. If you had three variants, then it would be 33/33/34. 

If you're hoping to begin an A/B test with an existing landing page, give the new variants a smaller percentage of traffic than the current champion variant, such as 70/30 or 80/20. 

New variants you choose to test are called 'Challenger' variants, whereas the variant you first start with is your 'Champion' variant. 

Once your variants are ready to go, you'll need to set traffic weights for each variant: 

Gif demonstrating how to set the weight of a variant

  1. Select the Weight number for either variant.
  2. Adjust the percentage to the desired value. If you are testing multiple variants, they must all add up to 100, or you will not be able to save the changes.
  3. Select the Republish button within the Overview screen to apply the new settings to your live page.

The weight settings are probability-based - for example, if you had two variants running at 50% each, the visitor would have a 50% chance to hit either-or. Think of this more as a coin flip versus 1, 2, 1, 2, 1, 2. It is not uncommon to have an uneven distribution of traffic to one variant or another.

Replacing Your Champion Variant

Over time you may decide that a 'Challenger' variant is performing better than your 'Champion' and you may wish to replace it.

Select the '...' symbol on the right side of the overview settings (near the Edit button).
From the list, select the option to Promote to Champion.

 This will move your old Champion into the Inactive Variants section near the bottom of the screen: 

Annoted image of the page overview showing how to promote variant to champion

Inactive variants are archived and are still accessible if you wish to review them or include them in future tests.

What to Test with an A/B Test

The great idea behind A/B Testing is that you are continually optimizing your page with new ideas to maximize your conversions.

Some common things to A/B test are:

  • An engaging Hero image/animation (you might want to test an image versus a video background)
  • A solid and engaging headline (experiment with different words, fonts, and layouts)
  • A clear Call to Action (CTA) (different positioning of a form, a button click)
  • Different kinds of social proof or testimonials

Frequently Asked Questions

Why is a variant with 0% still receiving traffic?

If you've published a page with multiple variants at any point, for example, variant A with 100% and variant B with 0%, both variants are still technically active - even variant B.

Returning visitors who had previously landed on variant B will continue to see variant B, even if its weight is 0%, while new visitors will be routed to variant A.

If you would like a variant to be inaccessible to returning visitors, you have to deactivate that variant and republish your page:

Annotated image of a red box circling the 'Deactive this variant' button.

Once you've deactivated the variant, there may still be a few visitors to that variant since their browsers have cached the page.

Rest assured, for most users, the browser cache will often refresh (if they're using their browser a lot), and they'll be re-routed to active variants only. 

Further Reading