Newsletter growth calculator
A list loses a percentage each month, so churn scales with size while signups usually do not. At 350 signups and 2% monthly churn, growth stalls at 17,500 subscribers — the point where 2% of the list equals 350. Adding more signups raises that ceiling proportionally; cutting churn raises it far more. It is the same arithmetic as a bucket with a hole, and the hole is what decides the water level.
Net growth is signups minus churn, compounded. A 5,000 list gaining 350 and losing 100 a month grows 5% monthly and reaches about 8,900 in a year — but because churn scales with list size, it eventually plateaus where churn equals signups.
How to project list growth
The plateau is the point most list projections miss. Signups tend to be roughly constant, driven by traffic and offer, while churn is a percentage and therefore grows with the list. The equilibrium sits where the percentage lost equals the flat number gained, and no amount of patience gets past it. Halving churn doubles the ceiling, which is why deliverability work, sensible send frequency and a genuine reason to stay subscribed are worth more in the long run than another signup form.
Questions
Around 0.2–0.5% per send in unsubscribes, plus list decay from dead addresses. Two per cent a month overall is common.