How list growth works
Each month you add new sign-ups and lose a percentage of the list to unsubscribes, bounces and spam complaints. Because the loss is a percentage, it grows as the list grows, while sign-ups usually stay roughly flat. Eventually the two meet and the list stops growing:
Worked example
A list of 5,000 adds 600 subscribers a month and loses 2% a month. In month one it loses 100 and gains 600, a net 500 (10% growth). After 12 months it reaches about 10,380 subscribers, having lost about 1,820 along the way. But the ceiling is 600 / 2% = 30,000: however long you wait, the list will level off near there unless sign-ups grow or churn falls.
Two levers, very different costs
| Change | New ceiling | Effect |
|---|---|---|
| Baseline: 600/month, 2% churn | 30,000 | - |
| Double sign-ups to 1,200/month | 60,000 | Needs more traffic or a better offer |
| Halve churn to 1% | 60,000 | Needs better content and list hygiene |
| Both | 120,000 | Compounding effect |
Cutting churn is often cheaper than doubling sign-ups. Send what you promised at sign-up, at the frequency you promised, and remove inactive subscribers before they turn into spam complaints.
Typical churn numbers
Many healthy lists lose somewhere around 0.5% to 3% a month to unsubscribes, bounces and complaints combined, plus a slower decay as email addresses go stale. If you send very often, buy lists or collect emails with a giveaway unrelated to your content, expect the high end or worse.
Growing sign-ups
- Offer something specific in exchange for the email - a checklist, a template, a calculator result - rather than "subscribe to our newsletter".
- Put the form where intent is highest: at the end of your most-read posts and inside tools people already use.
- Track sign-up rate per page using the conversion rate calculator, and tag your promotion links with the UTM builder to see which channels bring subscribers who stay.
Frequently asked questions
How do I calculate email list growth rate?
Subtract subscribers lost (unsubscribes, bounces, complaints) from new subscribers in the period, then divide by the list size at the start. 600 new minus 100 lost on a 5,000 list is a 10% monthly growth rate.
Why has my email list stopped growing?
Because churn is a percentage of the list, it grows as the list grows. When monthly losses equal monthly sign-ups, the list plateaus. The plateau is roughly new subscribers per month divided by monthly churn rate.
Should I remove inactive subscribers?
Usually yes, after a re-engagement attempt. Inactive addresses hurt deliverability and can turn into spam traps. A smaller, engaged list often earns more than a large, cold one.