Calculate how long an investment takes to pay for itself from its annual cash flow — both the simple payback period and the discounted payback period that accounts for the time value of money.
Time to recover an investment
The payback period is the time it takes for an investment's cash flows to recover its upfront cost. The simple payback divides the initial investment by the annual cash flow — fast and intuitive, but it ignores the time value of money. The discounted payback discounts each year's cash flow back to today before adding it up, so it reflects that money received later is worth less. The discounted payback is always longer than the simple payback.
For example, a $50,000 investment returning $12,000 a year has a simple payback of about 4.17 years. At an 8% discount rate, the discounted payback stretches to roughly 5.4 years, because the later cash flows are worth less in today's dollars. Payback period is a quick risk gauge — shorter is safer — but it ignores cash flows after breakeven, so pair it with NPV or IRR for a full picture.
Initial cost ÷ annual cash flow. A quick read on how fast you recover your money — ignores discounting.
Recovers the cost using cash flows discounted to present value. Always longer, and more realistic.
Payback ignores everything after breakeven. A project with a quick payback but poor long-term returns can still be a bad investment — check NPV/IRR too.
Payback period measures how long an investment takes to return its own cost. Its appeal is simplicity and its subject is risk rather than profit: a short payback means capital is exposed for less time, which matters when forecasts beyond a few years are guesswork. Its blind spots are serious, though — it ignores everything that happens after break-even, so a project that repays in three years then stops beats one that repays in four and runs for a decade. Use it alongside NPV, never instead of it.
Payback = Years before recovery + (Unrecovered cost ÷ Cash flow in the recovery year)With even cash flows: Payback = Initial investment ÷ Annual cash flowwhere:
Assumptions: Ignores the time value of money and all cash flows after break-even. The discounted payback variant fixes the first of those by discounting each flow before accumulating it.
Equipment costs $120,000 and returns uneven cash: $35,000, $45,000, $50,000 and $40,000.
ResultPayback = 2.8 years (about 2 years 10 months)
Discounting first at 10% pushes payback to roughly 3.3 years, because early dollars are worth more than the raw sum suggests. The gap between the two figures widens as the discount rate rises.