A/B Testing

A/B testing, also known as split testing, is a scientific method of comparing two slightly different versions of a newsletter to see which one resonates more with your audience. Instead of guessing what your readers like, you let the data speak for itself.

In a typical A/B test, you send “Version A” to 10% of your list and “Version B” to another 10%. Your email service provider then tracks which version performs better over a set period (usually 1-4 hours). Once a “winner” is determined, the platform automatically sends that version to the remaining 80% of your audience.

What Should You A/B Test?

While you can test almost anything, the most high-leverage elements in a newsletter are:

1. Subject Lines: This is the most common test. It directly impacts your open rate. You might test a curiosity-driven subject line against a direct, benefit-driven one.
2. Preheader Text: The snippet of text that appears after the subject line in many email clients. Testing this alongside the subject line can significantly boost interest.
3. Send Time: Does your audience prefer reading your newsletter during their morning coffee or on their Sunday evening wind-down? Testing different days and times can reveal hidden opportunities for engagement.
4. Call to Action (CTA): Test the button color, the size, the placement, or even the copy (e.g., “Join Now” vs. “Get My Free Guide”). This is the best way to improve your click-through rate.
5. From Name: Should the email come from “John Smith,” “The [Newsletter Name] Team,” or “John at [Newsletter Name]”?

A/B Testing Best Practices for 2026

To get the most accurate results from your tests, follow these rules:

• Test One Variable at a Time: If you change the subject line and the header image at the same time, you won’t know which change caused the difference in performance.
• Use a Significant Sample Size: If you only have 50 subscribers, an A/B test might not give you statistically significant data. Most pros recommend a list of at least 1,000 subscribers before relying heavily on split tests.
• Define Your Goal: Know what success looks like before you start. If you are testing subject lines, your primary metric is the open rate. If you are testing button colors, it’s the click rate.
• Don’t Over-Optimize: While testing is great, don’t let it paralyze your publishing schedule. Start with testing subject lines once a week and expand from there.

Tools for A/B Testing

Most modern newsletter platforms have built-in A/B testing suites. Beehiiv and ConvertKit both offer excellent, automated split-testing tools that handle the “winner selection” process for you. For those on a budget, MailerLite also provides robust testing features on its higher-tier plans.

By making A/B testing a regular part of your workflow, you can move away from “gut feelings” and start making data-driven decisions that lead to higher growth and better engagement for your subscribers.