SaaS Financial Model, 36 Months (MRR, churn, CAC, LTV, runway, breakeven)

Thirty-six months, one assumption sheet, and a summary that answers the questions a seed investor actually asks: MRR at 12, 24 and 36 months, runway, the month EBITDA turns positive, cumulative burn to get there, LTV:CAC and CAC payback.

• Customer build: opening, new, churned, closing, with growth in new adds.

• MRR from customers times ARPA, with ARPA expansion.

• Cash from gross profit less sales and marketing (CAC times new customers), payroll and overhead, each with its own growth rate.

• Cohort retention sheet shows what your churn assumption implies for each monthly cohort; paste real data over it when you have it.

• Runway and breakeven computed with explicit helper rows, not fragile array tricks, so they work in Excel and Google Sheets alike.

The default assumptions show a company that needs to raise: runway ten months, breakeven at month 32. That is the honest use of a model like this. No macros, no locked cells.

Who it is for: founders preparing a seed or Series A deck, and finance hires building the first proper model. The monthly build runs 36 months from a handful of yellow inputs (new customers, ARPA and expansion, churn, CAC, payroll and overhead) and produces MRR, gross profit, burn, cash and runway, LTV:CAC and CAC payback, with the breakeven month found automatically. A cohort retention view shows how churn compounds. Every number is a live formula you can trace back to its input, so an investor can audit the logic in the sheet itself.