A/B Test Splits let you test different messages, delays, or channels in your Automation by randomly dividing contacts into two paths (A and B). You can compare performance and choose the winner based on opens, clicks, or sales.
This article shows you how to add an A/B Test Split, analyze results, and optimize your workflows.
Before You Begin
A/B Test Splits are available on all Omnisend plans.
You need an active Automation workflow to add an A/B Test Split.
For reliable results, run your test until at least 100 contacts complete each path.
Each A/B Test Split supports two paths only (A and B). You can nest blocks to create more paths.
Contacts who are already in the workflow when you add an A/B Test Split will not enter it. Only new contacts will.
💡 If you want to test different send times in Campaigns (not Automation), use A/B Test Segments instead.
What You Can Test
We recommend choosing one element to test at a time. You can test:
Subject lines and preheaders – Find which wording drives more opens.
Delays – Determine the best time to send messages (e.g., 1 hour vs. 24 hours after trigger).
Channels – Compare email vs. SMS, or single-channel vs. multi-channel messages.
Message content – Test different images, copy, discounts, or CTAs.
After choosing your test element, decide on your success metric:
Open rate – Use when testing subject lines, preheaders, or sender names.
Click rate – Use when testing message content, CTAs, or offers.
Sales – Use when testing discounts, product recommendations, or urgency messaging.
💬 Learn more: Make Your Automated Messages More Relevant with A/B Testing.
Set Up an A/B Test Split
Step 1: Add the A/B Test Split Block
Open your Automation or create a new Automation.
Drag the A/B Test Split block from the left sidebar into your workflow sequence.
The A/B Test Split block has these properties:
Supports two paths only (A and B). You can nest additional A/B Test blocks to create more paths.
Unlike Conditional Splits, contacts pass through the A/B Test Split only once.
You can add any message block (email, SMS, push) or delays to both paths. You cannot add Conditional Splits inside A/B Test paths.
⚠️ Important: If you add an A/B Test Split to an already-enabled workflow, it won't apply to contacts already in the workflow, only to those entering later.
Step 2: Set the Split Percentage
In the A/B Test Split settings, choose what percentage of contacts will follow path A vs. path B.
The default is 50/50, which is best for testing. However, you can adjust it:
50/50 – Use for standard A/B tests (equal comparison).
30/70 or 20/80 – Use when testing a risky change (e.g., send the safer version to more contacts).
90/10 – Use to test a new idea on a small audience before full rollout.
Step 3: Add Messages to Each Path
Build your message blocks inside paths A and B:
To test delays, add the same message to both paths with different delay blocks.
To test content, create two different messages (one in path A, one in path B).
To test channels, add an email to path A and SMS to path B.
💡 Tip: You can duplicate a message block by clicking the three-dot menu → Duplicate, then drag it to the other path.
Step 4: Enable Your Workflow
Once you've configured both paths, click Enable to start the A/B test.
Contacts entering the workflow will be randomly assigned to path A or path B based on your split percentage.
Analyze Your A/B Test Results
View Performance Data
After running your test, click Show stats in the workflow editor to see 30-day performance data for each path:
Sent – Number of messages sent.
Opened – Open rate (%).
Clicked – Click-through rate (%).
Sales – Revenue attributed to messages in this path.
Completed – Number of contacts who passed through this step.
Skipped – Contacts who didn't receive the message due to opt-in status.
For full performance data, go to Reports → Automation → select your workflow.
Choose the Winning Path
Once you have enough data (at least 100 contacts per path or 2+ weeks of testing), identify the better performer:
If testing open rate, compare Opened (%).
If testing click rate, compare Clicked (%).
If testing sales, compare Sales revenue.
⚠️ Important: Focus on the metric tied to your test goal. For example, if you're testing subject lines, open rate matters most. Email content affects clicks and sales, not opens.
Apply the Winner Path
Once you've identified the winning path, adjust the split percentage:
Click the A/B Test Split block in your workflow.
Select the winning path → Click Pick path A or Pick path B.
Click Save.
All future contacts will now follow the winning path. You can also add Conditional Splits after the A/B Test to further personalize based on engagement.
Delete or Disable an A/B Test Split
If you want to remove an A/B Test Split:
Click the three-dot menu on the A/B Test Split block → Select Delete.
Choose:
Delete entire block – Removes both paths.
Delete path A – Keeps only path B.
Delete path B – Keeps only path A.
💡 Alternative: Instead of deleting, set one path to 0% and the other to 100% to disable a path without removing it.
Example Use Cases
Create 3+ Paths with Nested A/B Test Splits
Although each A/B Test Split supports only two paths, you can nest blocks to create more:
Add an A/B Test Split with a 66/34 split.
Inside the 66% path, add another A/B Test Split with a 50/50 split.
This creates three equal paths: 33% / 33% / 34%
You can repeat this process to create four or more paths.
Test Delays by Duplicating Messages
To test which send delay works best:
Add an A/B Test Split with a 50/50 split.
Add the same message to both paths.
Set different delays (e.g., 1 hour in path A, 24 hours in path B).
Compare performance after 2+ weeks.
💡 Tip: Duplicate your message block and drag it to both paths to save time.
FAQ
Does the A/B test in Automation automatically send the winning version?
No. Unlike Email Campaigns, automation A/B tests do not automatically select and send a winner. The A/B Test Split randomly divides contacts as they enter the workflow. After reviewing results in Show Stats or Reports, manually select the winning path to send all future contacts through it.
If I add an A/B Test Split to a live workflow, will it affect contacts already in it?
No. The A/B Test Split only applies to new contacts entering the workflow after you publish the change. Contacts currently in the workflow will continue on the original path without entering the A/B test.
Need more ideas or assistance? Feel free to jump on a chat or email us at [email protected].