A/B Test a Flow Email



Klaviyo's A/B testing feature for flows allows you to easily test different subject lines and even completely different email content to help you refine your messaging. 

Flow A/B testing is the process of:

  1. Creating a single flow email and scheduling this email to send after a certain number of hours or days
  2. Configuring 2 or more email variations for this single flow email -- adjusting the subject line or core email content for each variation
  3. Selecting the weight of each variation, to establish the percentage of recipients that will get each email
  4. Observing the performance of each variation over time, to determine which should be considered the "winner"

Once you determine that one variation is out-performing the others, you can delete the other variations so that 100% of your recipients will receive the tested winner. 

Set Up a Flow Email A/B Test

To set up A/B testing for an email in any flow, follow the directions below:

  1. Click on an existing email in your flow, or create a new flow email and configure the content for one variation
  2. When in the Message Content view, scroll to the bottom; here you will see an Add Variation option


  3. You will be directed to a Manage Variations window where you can edit and add additional variations - to add another variation, click on the Actions dropdown for one of the existing variations and click Duplicate variation
  4. Lastly, select the Weight of each variation - this will establish the percentage of recipients that will get each variation; it's common practice to weight each variation equally


After setting your flow email with A/B testing live, you can monitor the performance of each variation across the following metrics:

  • Recipients: How many people received the email
  • Opens: What percentage/number of people opened the email 
  • Clicks: What percentage/number of people clicked through the email
  • Placed Order: 
    • Total of recipients who placed an order
    • Total dollar amount that was made from each email

Flow Email A/B Testing Examples

A few examples of how Klaviyo customers use A/B testing:

  • Experimenting with new subject lines or types of emails in a very low-risk way. Because A/B tests allow you to send unique variations to a limited subset of people, this is a great way to try something new and get real data to measure how well the idea worked (rather than having to debate the anticipated outcome without metrics to back up your assumptions).
  • Understanding the right discount to offer and whether they are necessary. Because you can easily test completely different email content, A/B tests are a great way to figure out if you really need to offer 20% off or if you can instead get away with 10% or no offer at all.
  • Figuring out whether plain text emails perform better than image-heavy HTML emails. Many of our customers test out both very short personal emails as well as traditional emails with images and complex layouts. Both work well for different purposes, but A/B testing will give you actual numbers to analyze when considering which approach is best.
Was this article helpful?
4 out of 6 found this helpful