Email List Growth Calculator

Project list size forward given sign-up rate, unsubscribes and bounce attrition.

About Email List Growth Calculator

A list is a leaky bucket: attrition scales with size while additions usually do not, so growth slows and eventually stops at the point where additions equal attrition. The closed form of that geometric series gives the projection directly. Every list has an equilibrium size set by additions divided by attrition rate, and no amount of time gets it past that ceiling without raising sign-ups or cutting churn.

Formula

Email List Growth

List next month = list × (1 − attrition rate) + new subscribers

attrition rate: Unsubscribes plus bounces and cleaning, as a monthly share

Worked example

With the default values below, Email List Growth Calculator returns Projected List Size of 36,837. Change any input above and every figure here is recalculated in your browser.

Inputs used

Current list sizeminimum 0: 25,000
New subscribers per monthminimum 0: 1,200
Monthly unsubscribe rateaccepts 0–100 %: 0.4 %
Monthly bounce and cleaning attritionaccepts 0–100 %: 0.3 %
Months to projectaccepts 1–60 months: 12 months

Results

Projected List Size: 36,837
Net Growth in Month One: 1,025
Net Monthly Growth Rate: 4.100%
Subscribers Lost Over the Period: 2,563
Verdict: Growing — additions outpace attrition

Step by step

1Values used
2Email List Growth
3Projected List Size= 36,837
4Net Growth in Month One= 1,025
5Net Monthly Growth Rate= 4.100
6Subscribers Lost Over the Period= 2,563
7Verdict= Growing — additions outpace attrition

Assumptions and limits

The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
This is an estimate for general information and not professional financial, tax or legal advice. See the full disclaimer for the limits that apply to this kind of calculator.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is Email List Growth calculated?

List next month = list × (1 − attrition rate) + new subscribers A list is a leaky bucket: attrition scales with size while additions usually do not, so growth slows and eventually stops at the point where additions equal attrition. The closed form of that geometric series gives the projection directly.

Why does Email List Growth matter?

Every list has an equilibrium size set by additions divided by attrition rate, and no amount of time gets it past that ceiling without raising sign-ups or cutting churn.

What values do I need to enter?

This calculator takes 5 inputs: Current list size, New subscribers per month, Monthly unsubscribe rate, Monthly bounce and cleaning attrition, Months to project. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.