5 Klaviyo Experiments That Explode eCommerce List Growth in 2025
Email marketing continues to be one of the most profitable channels for eCommerce brands, but the foundation of any successful campaign is a healthy, fast-growing email list. At Elite Brands, our mission is to scale eCommerce stores to eight figures and beyond, and one of the fastest ways to accelerate growth is by optimizing your Klaviyo signup forms.
Too often, brands treat signup forms as “set and forget” tools, averaging around a 2% submission rate. But what if that same form could deliver 10%, 15%, or even 20% conversions? That’s exactly what we’ve achieved for our clients through structured A/B testing and consumer-behavior driven strategies.
In this article, we’ll walk through five proven Klaviyo experiments that consistently transform underperforming pop-ups into powerful list-building machines. From binary opt-ins and mystery discounts to form sizing, timing tests, and countdown timers, these experiments not only grow your subscriber base but also drive higher engagement and conversions on the backend. These methods are battle-tested, scalable, and highly effective.
Why Signup Forms Are the Key to eCommerce Growth
For many brands, signup forms feel like an annoyance rather than an opportunity. Yet the reality is that a well-optimized Klaviyo signup form is one of the most powerful tools you can use to scale revenue. The math is simple: every new subscriber added to your list increases your potential revenue per recipient. By boosting conversion rates on these forms, you’re adding more prospects into your email marketing engine without increasing ad spend.
When we first audit a new eCommerce client, we often see signup forms converting at only 2%. With some quick-win experiments, we regularly boost this number to 10–12%, and in some cases up to 20%. Imagine your ecom brand’s site receives 100,000 monthly visitors. At 2% conversions, that’s just 2,000 emails captured. At 12%, you’re suddenly at 12,000 emails — six times the growth without any additional traffic investment.
These gains are achieved through a structured testing agenda, where we isolate variables such as the offer, design, urgency, timing, and friction points. Our five high-impact experiments are:
Binary Opt-In Test (Yes/No Step) – Simplifying the first decision increases completion.
Mystery Discount Incentives – Curiosity drives engagement and higher conversions.
Form Layout & Size Testing (Pop-Up vs Fly-Out vs Full-Page) – Design matters more than most think.
Timing Optimization (2–10 Second Intervals & Scroll Triggers) – Showing the form at the right moment prevents drop-offs.
Countdown Timers for Scarcity – Creating urgency accelerates action.
Each of these tactics taps into core consumer psychology principles: micro-commitments, curiosity, urgency, and friction reduction. And when layered together, the compounding results can make a massive difference to your customer acquisition strategy.
The 5 Klaviyo Experiments You Must Test in 2025
Let’s break down the five experiments that have proven to consistently deliver powerful results for our eCommerce brands.
1. Binary Opt-In Test
Instead of presenting a form immediately asking for an email, we first ask a simple “Yes, I want a discount” or “No, not for me” question. This small commitment dramatically increases the likelihood of following through. Uplifts of 3–5x are not uncommon, and the test requires minimal setup.
2. Mystery Discount Offers
People love curiosity. Instead of showing “10% off” upfront, we test “Unlock your mystery discount.” This reframe drives higher opt-ins and also improves conversion rates in the backend flows. Subscribers are more likely to check their email for the reveal, boosting open rates and revenue per recipient.
3. Form Size & Layout Variations
Klaviyo allows you to run signup forms as a pop-up, fly-out, or full-page takeover. In testing, full-page forms consistently outperform smaller versions, sometimes delivering up to a 15% lift in submissions. However, brands with short-cycle impulse buys (like fashion) should monitor bounce rates carefully, while long-consideration products (like furniture or luxury items) tend to benefit most.
4. Timing Optimization
When is the best time to show your form? Testing intervals like 2, 4, 6, 8, and 10 seconds reveals the sweet spot. Too soon, and users bounce; too late, and you lose them. Scroll-based or multi-page triggers are also strong alternatives. Timing tests are especially valuable for ecom brands, where browsing behavior can vary significantly.
5. Countdown Timers
Scarcity is a timeless motivator. Adding a live countdown timer (10 minutes, 1 hour, or customized windows) signals urgency and compels users to act quickly. Klaviyo now supports dynamic timers directly in forms, making this one of the easiest high-ROI tests to implement.
Beyond these five, we recommend testing teasers (small re-clickable icons after a form is closed), optimizing images for your niche, experimenting with CTA copywriting, and excluding disruptive placements like checkout pages.
Finally, don’t forget SMS. Recent tests show including an SMS field alongside email can actually increase submission rates rather than hurting them. For existing subscribers, run a separate SMS-only form. Together, email and SMS create a powerful retention and remarketing engine.
When implemented systematically, these five experiments can transform your email list growth from stagnant to explosive, driving long-term revenue for your ecom business.