Signal Lab · Model
Payback Period Calculator
Years to recover the investment — simple payback and discounted payback (cash flows present-valued at your discount rate). Project years, not customer-channel months.
Illustrative sample (100k · 30k × 5 · 10%). Not financial advice. Distinct from LTV:CAC & CAC Payback.
Outlay, discount rate, and cash flows
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Simple and discounted payback
Fractional year = year_before + remaining ÷ CF that year. Cumulative helpers below.
Equations
- CumUndisc[t] = Σ CF1…t · SimplePayback when cum crosses Initial
- PVt = CFt ÷ (1+r)t · CumDisc similarly → DiscountedPaybackYears
- Fractional ≈ year_before + (Initial − Cum_before) ÷ CF_year
How this is calculated
- Simple payback (years) — years until cumulative undiscounted CF recovers Initial
- Discounted payback (years) — same using present-valued cash flows at your discount rate
- Fractional year ≈ year before crossing + remaining balance ÷ that year’s CF (or PV)
- This is project payback in years — not LTV:CAC / CAC Payback (customer unit-economics months)
Illustrative — not financial advice.
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