No vendor publishes a headline list growth benchmark, but the inputs are all on the record: capture converts at 2.1% on popups and 6.47% on landing pages, and every campaign send costs about 0.2% of its audience in unsubscribes. The formula does the rest.
Ask what a good list growth rate is and you will find plenty of confident percentages and no citations, because the honest answer is that no major vendor publishes one. Klaviyo’s benchmark report covers opens, clicks and orders. Omnisend’s covers the same plus revenue per email. List growth rate, the metric that decides how big all those other numbers get to be, has no published cross-industry average.
What does exist, in unusually good detail, is data for both halves of the formula. So this piece does the assembly: the formula, the published inflow rates, the published outflow rates, and a calculator that turns your traffic into a growth projection using only sourced numbers.
List growth rate for a period = (new subscribers - unsubscribes - removed addresses) / list size at period start × 100.
The subtractions matter as much as the additions. Unsubscribes are the visible loss; the quieter ones are hard bounces and the addresses you prune for chronic inactivity (which you should, for the deliverability reasons laid out in our win-back mechanics piece). A store that only watches signups is reading half its own ledger.
The capture side is the best-documented corner of email marketing right now, thanks to Omnisend publishing its form data at scale. Its 2025 dataset covers 1.24 billion popup displays that collected 26.4 million emails, an average popup conversion of 2.1%. The same vendor’s form-type breakdown, published January 30, 2026, adds the rest of the menu:
| Capture surface | Average signup rate | Notes from the published data |
|---|---|---|
| Landing page form | 6.47% | Best average of any surface; gamified versions reach 11.02% |
| Popup | 3.77% | 2.1% average across the full display dataset; 3 to 5% is "good" per Omnisend's tiers |
| Flyout / teaser | 3.24% | Less intrusive, nearly popup-level performance |
| Embedded form | 1.28% | Footer and inline forms; discount offers embedded convert at just 0.19% |
Two numbers explain most of the variance within each row. Popups with a discount converted at 2.4% versus 1.7% without, and a 6 to 10 second display delay outperformed instant popups 2.4% to 1.9%. The tactics stack, and they get their own ranked treatment with receipts in the companion piece.
Every send costs subscribers, at rates the benchmark reports state plainly. Omnisend’s 2025 dataset puts the campaign unsubscribe rate at 0.20% of recipients per send, with automated emails higher at 0.59% (welcome emails top the automation table at 0.87%, the price of introducing yourself). Mailchimp’s long-running table has ecommerce at 0.19% unsubscribes per campaign, agreeing almost exactly.
The compounding is what stings. Four campaigns a month at 0.20% each drains roughly 0.8% of the list monthly, nearly 10% of the list per year, before a single bounce or pruned address. That is the treadmill under every list: a store that captures nothing does not stay flat, it shrinks on a schedule set by its own send calendar.
Defaults use published figures: 2.1% average popup conversion (Omnisend, 1.24B displays) and 0.20% unsubscribes per campaign send (Omnisend 2025 dataset). The projection ignores bounces, pruning and automation unsubscribes, so treat it as the optimistic bound.
Play with the capture rate field and notice the asymmetry: moving capture from 2.1% to 3% changes the twelve-month picture more than halving your send frequency does, because inflow scales with traffic while the drain scales with the list. That asymmetry is the entire strategic argument for working the capture side first.
Track it monthly, and split it into its two components on the same dashboard: gross captures and gross losses. A falling growth rate with steady captures means a decay problem (frequency, relevance, list age); a falling rate with steady losses means a capture problem (traffic mix, form fatigue, weak offer). The single blended number cannot tell you which lever to pull, but the split always can.
And keep the quality guardrail in view. Growth rate counts heads, while mailbox providers count engagement, so a spike of low-intent signups can buy you a bigger list and worse inbox placement in the same month. The published capture rates above all come from stores offering something real at signup, which then has to be delivered by a welcome flow that turns the address into a customer. Capture, deliver, measure, prune. The growth rate is just the scoreboard for that loop.
Capture-side figures are from two Omnisend publications: the popup performance report of February 9, 2026 (1.24 billion displays, 26.4 million emails collected, 2.1% average conversion, the 1.5/3/5% performance tiers, discount 2.4% vs 1.7%, delay and gamification effects) and the signup form article of January 30, 2026 (form-type averages: landing pages 6.47%, popups 3.77%, flyouts 3.24%, embedded 1.28%, plus gamified and multistep variants). Outflow figures are from Omnisend's benchmarks article of May 12, 2026 (0.20% campaign and 0.59% automation unsubscribe rates from the 2025 dataset) and Mailchimp's benchmarks page checked July 17, 2026 (0.19% ecommerce unsubscribe rate, data updated December 2023). The claim that no major vendor publishes a list growth rate benchmark reflects the Klaviyo, Omnisend and Mailchimp benchmark publications reviewed for this piece as of July 2026; if one appears, this article gets updated. The calculator combines these published rates with your inputs and makes no claims beyond that arithmetic.
There is no published cross-industry average to quote, and any post that gives you one without a source is making it up. The workable standard is internal: your list should grow faster than it decays, meaning monthly captures comfortably above monthly unsubscribes plus removals, with the calculator below showing your own number from published input rates.
Per send, at roughly the published unsubscribe rates: 0.20% of recipients per campaign in Omnisend's 2025 dataset and 0.19% for ecommerce in Mailchimp's table, before counting bounces and addresses that simply go dead. A list receiving four campaigns a month loses roughly 0.8% of itself monthly to unsubscribes alone.
No. Growth rate measures volume, not quality, and mailbox providers score engagement. A thousand new subscribers from a viral giveaway who never open will cost deliverability that your buyers pay for. Pair the growth number with engagement, and prune dead weight the way our win-back mechanics piece describes.
The published average hides huge spread by format and setup. Omnisend's own tiering calls under 1.5% underperforming, 1.5 to 3% average, 3 to 5% good, above 5% excellent, and its data shows discounts (2.4% vs 1.7%), a 6 to 10 second delay (2.4%) and gamification (3.5%) as the levers that move a popup up those tiers.