Buyer economics
One cohort: GMV retention, LTV to CAC, payback.
By Surojit Chakraverti, founder of L3VLUP and an investor running a long-short healthcare and technology equities strategy.
On this subject: buyer economics.Updated 2 October 2026
Part of technology company financial models, with the models, labs and guides around it.
What it does
One cohort of buyers followed through five years of tenure. Orders per buyer acquired are the share still active times their frequency; their ratio to the first year is the cohort’s GMV retention, which can exceed 100% when the survivors order enough more. Contribution per buyer acquired is that times contribution per order; discounted over the horizon it is the lifetime value, set against the marketing cost of acquiring the buyer, and the cumulative figure gives the payback year.
Where it lives
The same schedule in each model that carries it, with the rows to open. Open a model in the browser, go to the sheet, and click the lines.
- Assumptions, row 32: Marketing cost per new buyer ($)
- Assumptions, row 35: Discount rate for a buyer’s lifetime value
- Buyer Economics, rows 6–13: Years since acquisition, Share of buyers still active, Orders per buyer acquired: still active x frequency, GMV retention against the year acquired…
- Buyer Economics, rows 16–19: Contribution per order at FY1 basket size ($), Five-year lifetime value per buyer acquired, discounted ($), Lifetime value / cost per new buyer, Year of tenure in which contribution repays the acquisition cost (6 means not within five)
What a reviewer looks for
- LTV on GMV or revenue rather than contribution.
- An unlimited horizon.
- Buyer retention quoted without frequency.
Learn it, then build it
Build · Lab · ~12 min
Marketplace Economics
Turn GMV into net revenue and contribution per order, read a cohort’s GMV retention from retention and frequency, and find the payback year on a buyer.
Build · Lab · ~12 min
Unit Economics
Build an LTV:CAC you could defend under questioning, and answer payback as its own question.
Read · Guide · 11 min
SaaS Operating Models: ARR, Sales Capacity, Billings and the Metrics That Follow
Vocabulary: Cohort GMV Retention, LTV to CAC, Contribution Margin.