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Subscription CAC from surviving cycles
The first-order max CAC tool answers “what can I bid on the click if the customer never rebills?” This one answers the other question: what is the cohort worth if some of them stay. It is not billed LTV. It is contribution from a first order plus the surviving subscription cycles, divided by starters.
Pair: Subscription CAC from surviving cycles.
Clock
Cycle k bills on day k × days-per-cycle. A 30-day cycle means day 30 is cycle 1 and day 60 is cycle 2. Day 0 is the product purchase (AOV × product gross margin). It is not a subscription cycle.
If your CRM bills every 14 days, set days-per-cycle to 14 or the clock is a lie.
Drop-off is a count
Subscriptions started is the cohort. Drop-off per cycle is how many leave after each bill. 100 starters and 25 drop-off bills 100, then 75, then 50, then 25, then none. It is not a 25% churn field. If you have a percent, convert it to a count on this cohort first.
Gross margin here is (price − landed COGS) / price. Type 65, not 0.65. This calculator does not subtract refunds, processor fees, RDR, or reserve drag. Those stay on the first-order tool. Do not blend the two numbers in one cell.
What the big number is
Allowable CAC per starter = (product contribution + all surviving rebill contribution) / starters. That is LTV-ish if you can actually collect those later cycles: MIT approval, a MID that is not at threshold, stock to ship. If you cannot float to cycle 2, cap the bid with first-order CAC, not this.
Related: traffic (the bid), payments (settled, not billed), MIDs (rebill MIT), stock (landed COGS).
Procedure
- Take first-order AOV that settled, not CRM “paid.”
- Put product gross margin from landed COGS (stock), as a percent.
- Name the cohort: how many subscriptions actually started, not how many landing-page clicks.
- Put subscription gross margin on the rebill amount (override rebill $ if the continuity price is not AOV).
- Put drop-off as a count per cycle from your last 90 days of rebills, not a hope.
- Set days per cycle to the bill period in the CRM (30, 14, 60). Confirm that day 60 is the cycle you think it is.
- Allowable CAC per starter is the bid cap only if you can float to those later cycles. Otherwise cap with the first-order CAC tool.
Failure modes
- Treating billed LTV as cash in week one and bidding it on day 0.
- Entering 0.65 when the field is a percent (65).
- Using a drop-off percent in a count field.
- Ignoring that rebills still need a MID that can take MIT / recurring volume.
- Skipping refunds and chargebacks — this calculator does not subtract them.
Worked example
None on this page yet. When one lands it will be a real case: what broke, the number, and what changed. Not a composite.
Glossary
- Starter
- One customer who paid the first-order AOV and entered the subscription cohort. Allowable CAC is per starter, not per remaining rebill.
- Cycle clock
- Cycle k bills on day k × days-per-cycle. With a 30-day cycle, day 60 is cycle 2. Day 0 is the first-order product, not a subscription cycle.
- Drop-off per cycle
- A count that leaves after each billed cycle. 100 starters and 25 drop-off → 100, 75, 50, 25, then 0. Not a percent.
- Gross margin here
- (Price − landed COGS) / price. It is not contribution after refunds, fees, RDR, or reserve drag. Those belong on the first-order CAC tool.
Work with us — We run this job on your accounts. Services
FAQ
- Is day 60 cycle 2?
- Yes when days per cycle is 30. Cycle k bills on day k times days-per-cycle. Day 0 is the first-order product, not a subscription cycle.
- Is allowable CAC cash in week one?
- Only if you can float to later cycles. Otherwise cap bids with the first-order CAC tool.