---
title: "Subscriber lifetime: definition and formula"
description: "How many renewals a subscriber is expected to take before leaving. Churn puts a ceiling on it, and on what a subscriber can ever earn."
url: https://offersuite.io/glossary/subscriber-lifetime
updated: 2026-10-13
---

# Subscriber lifetime

How many renewals a subscriber is expected to take before leaving. Churn puts a ceiling on it, and on what a subscriber can ever earn.

## In plain words

Subscriber lifetime is the number of renewals you can expect from one subscriber, on average, before they cancel. It follows directly from the renewal rates: each renewal is taken by a smaller share than the last, and the shares add up to a finite total.

That total is a ceiling. However long you wait, a subscriber will not take more renewals on average than the renewal rates allow. If the loss on the first order is larger than that many renewals can earn, the subscription never pays back, at any horizon.

## Formula

- Expected lifetime renewals = Σ over every renewal of the share of subscribers still active when it ships
- At a constant rate r: r ÷ (1 − r)

## Worked example

On a renewal curve that starts at 70.0% and settles at 90.0%, the engine expects 4.24 renewals in a subscriber's first twelve months and 5.81 over a whole lifetime.

Each renewal keeps $11.68, so the first order may lose no more than that many renewals can earn. Here it loses $26.21 against the acquisition cost, which the lifetime covers.

### The example order

A $40.00 bag of coffee, shipped free, every cost counted

Revenue $40.00 to contribution margin $15.36 (38.4%)

Revenue

$40.00

Cost of goods

−$12.00

Pick and pack

−$1.18

Packaging

−$0.50

Shipping label

−$7.50

Card fee per order

−$0.30

Refunds

−$2.00

Card processing

−$1.16

Contribution margin

$15.36

2 declared kinds cost nothing on this option

Computed by the margin engine in Offer Suite's own code, in whole cents, from a $40.00 bag of coffee with a $12.00 unit cost.

## Average lifetime is not how long the typical subscriber stays

The average is pulled up by a loyal minority who stay for years. Most subscribers leave well before it. With a first renewal rate of 70%, three in ten are gone after one order, while the average still comes out near six renewals.

## Using it

Compare the lifetime with your payback point. If a subscriber pays back at the fifth renewal and the expected lifetime is under six, the plan has almost no room for error. Lifting the first renewal's rate usually does more for lifetime than anything later, because every later renewal depends on it.

## In Offer Suite

Offer Suite's payback calculation reports the expected renewals over a lifetime, with the curve's last rate carried on, and says outright when churn caps a subscriber's lifetime below the loss the first order leaves.

Source: Offer Suite's margin engine.

## Related

- [Glossary **Glossary of offer economics** The terms behind offer profit, defined plainly with their formulas and a worked number: contribution margin, profit per visitor, break-even lift and more.](https://offersuite.io/glossary)
- [Calculator **Subscription payback calculator: CAC and churn** How much a subscriber's first order loses against what you paid to acquire them, how many renewals it takes to earn that back with churn, and in which month.](https://offersuite.io/calculators/subscription-payback)
- [Calculator **Subscription first order vs renewal calculator** Margin on a subscription's first order and on each renewal, and the expected profit per subscriber over time at your retention, against a one-time buyer.](https://offersuite.io/calculators/subscription-first-order-vs-renewal)
- [Glossary **Churn rate: definition, formula and example** The share of subscribers who leave in a period, or between one order and the next. The complement of retention, and it compounds the same way.](https://offersuite.io/glossary/churn-rate)
- [Glossary **Renewal curve: definition, formula and example** The renewal rate at each order number: who takes the second order, the third, the fourth. It starts low and settles higher as the casual leave.](https://offersuite.io/glossary/renewal-curve)
- [Glossary **CAC payback period: definition, formula and example** How long a customer takes to earn back what they cost to acquire. With churn counted, it is later than the simple division suggests.](https://offersuite.io/glossary/cac-payback-period)