What a customer base forecast shows if churn holds
The short answer
Take today's active customers, multiply by one minus your annual churn rate, then add the new and reactivated customers you expect over the year, and you have a 12-month customer base forecast. Run it at current rates first, then with churn and acquisition each moved a few points, to show what is at stake.
Customer churn forecast for the active base
Why it matters
Revenue forecasts often assume the customer base holds steady, yet churn running slightly ahead of acquisition shrinks the base every year. A customer base forecast makes that drift visible, so leadership can decide whether to invest in retention, acquisition or both.
The question to ask
Copy this into Lexi as written.
How to work it out
1. Start with the active base. Count active customers under your written definition, such as a purchase in the past 12 months.
2. Apply churn. Use the share of active customers who lapsed over the past year as the churn rate, by segment if rates differ.
3. Add inflows. Add expected new customers and reactivated lapsed customers, based on the past year's rates, and compare scenarios.
What the answer looks like
Illustrative output on sample data
Illustrative example: how Lexi answers this for a home improvement retailer with 420,000 active customers. It projects the base forward at current churn, acquisition and reactivation rates.
- Retained at 34% annual churn: 277,200
- Expected new customers: 118,000
- Expected reactivations: 16,000
- Forecast active base: 411,200
What the data shows
At current rates, the base shrinks by about 8,800 customers, or 2%.
What it means
A two-point rise in churn would double the decline to about 17,200. Churn is highest among customers whose only purchase was one large project, such as a kitchen.
What to do
Follow up large project customers with smaller related projects in their first year.
The forecast holds rates steady, so a new competitor or promotion would change it. Want me to show churn by segment?
Frequently asked questions
What counts as the active customer base?
Customers who meet your written active definition, typically at least one purchase in the past 12 months, counted once each after matching records across channels. Use the same definition for the starting count, the churn rate and the forecast, or the numbers will not line up.
Why can the customer base shrink while revenue grows?
Revenue can rise on price increases or higher spend from remaining customers while fewer customers buy. That works for a while, but a shrinking base leaves fewer people to sell to next year. Track active customers next to revenue to see whether growth rests on a widening or narrowing base.
Should churn be forecast by segment?
Yes, when rates differ a lot between groups. New customers, one-off project buyers and regular customers churn at very different rates, and a single average hides shifts in the mix. Forecasting each segment and adding them up gives a more reliable base and shows where retention effort pays most.