Why newsletter growth breaks the usual ad maths
In ecommerce the conversion pays for itself immediately. A subscriber does not. You pay today for revenue that arrives later through whatever your newsletter actually monetises: ads, affiliate, a paid tier, or a product you sell to the list. Until you know the value of a subscriber over time, you cannot say whether any cost per subscriber is good or bad.
That makes two numbers decisive. The first is revenue per subscriber over a defined window, which you get from your own cohorts rather than from a benchmark. The second is how many of the people who sign up are still opening anything a month later, because a subscriber who never opens is a cost with no revenue attached.
Geography usually matters more than targeting
Cost per signup varies enormously by country, and the cheapest countries are frequently the ones that monetise worst. An unrestricted campaign will find the cheapest signups available, which is exactly the wrong optimisation if your revenue comes from advertisers who pay for a particular market. Restrict countries deliberately, and judge each market on revenue per subscriber rather than on cost per subscriber.
Which event to optimise for
| Event | When it is the right choice |
|---|
| Confirmed subscriber, after double opt-in | Best quality signal. Needs enough volume to learn from |
| Signup submitted | The usual starting point. Move past it once you can pass a later event |
| Landing page view | Only to bootstrap when signup volume is too low to optimise on |
Sending the confirmed event back to Meta needs a server-side connection. The Conversions API guide covers it.
Common questions
Does this connect to my email platform or ad account?
No. There is no login, no OAuth and no integration with your email service or ad account. It applies list-growth rules to the numbers you type on this page. Nothing is read from your systems and nothing is written to them.
What should a newsletter subscriber cost?
There is no general answer, because it depends entirely on what a subscriber earns you. The useful number is revenue per subscriber over a window you can actually measure, and your maximum cost per signup is some fraction of that, chosen according to how long you are willing to wait to break even. Benchmarks from other newsletters are close to useless here, because monetisation models differ so much.
I am getting signups but the list is dead.
Almost always an optimisation target problem. If Meta is optimising for form submissions, it finds people who submit forms, which is not the same as people who read newsletters. Send a later event back, such as a confirmed opt-in or a first open, and let it optimise toward that. Tag Meta-acquired subscribers separately in your email platform so you can see their open rate as its own cohort.
Should I use Instant Forms or a landing page?
Instant Forms produce cheaper signups and worse retention, because nobody leaves Facebook and the decision costs nothing. A landing page costs more per signup and generally produces subscribers who actually read. If you can only measure one thing, measure the open rate of each source after 30 days rather than the cost per signup.
Why are some of my signups obviously fake?
Cheap, unrestricted delivery attracts low-quality and automated signups, especially on Instant Forms with prefilled fields. Restrict countries, add a qualifying question or a manual field, and require double opt-in so a fake address never becomes a subscriber. Spam or fake leads covers the pattern.
Built by Jonas Sluijs, former Meta growth lead, $500M+ in ad spend.