Calculators
Email List Growth Calculator
Forecast the size of an email list month by month from new sign-ups and the rate subscribers leave.
- Runs in your browser
- Nothing uploaded
The tool
Enter your numbers below. Results update as you type, and nothing leaves your browser.
Everything you enter stays on your own machine. Nothing is sent to us or to anyone else, which you can confirm in your browser network tab.
What people use it for
- Forecasting list size for a launch or sponsorship deal
- Measuring the effect of a new lead magnet
- Finding the list ceiling at current churn
- Setting monthly sign-up targets
About this tool
What the Email List Growth Calculator does
An email list grows by new sign-ups and shrinks through unsubscribes, bounces and complaints. This calculator applies both every month, so you can see the list size you will actually have, and the point where churn catches up with sign-ups.
Formula
- Next month = this month × (1 − churn rate) + new subscribers
- Long-run ceiling = new subscribers per month ÷ monthly churn rate
Worked example
Using the starting values in the calculator above:
| Input | Value |
|---|---|
| Current subscribers | 5,000 |
| New subscribers per month | 600 |
| Monthly list churn | 1.5% |
| Months to forecast | 12 months |
| Result | Value |
|---|---|
| List size at the end | 10,805 |
| Net growth | 116.1% |
| Long-run list ceiling | 40,000 |
How to read the result
Every list has a ceiling where monthly churn equals monthly sign-ups. Once you are near it, adding traffic to sign-up forms or cutting churn are the only ways to grow.
Regularly removing inactive subscribers raises measured churn but improves deliverability, which usually earns more than a bigger, colder list.
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Questions
Questions about this tool
The things clients actually want to know — costs, timelines, ownership and what happens after launch.
Many lists lose somewhere between 0.5% and 2% a month to unsubscribes, bounces and complaints, plus natural decay as addresses go stale.
Because churn is a percentage of a growing list while sign-ups are roughly constant. Eventually the two cancel out at the list ceiling.
Usually yes. Inactive addresses depress engagement signals that mailbox providers use for inbox placement.
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