Discounted Payback Period Calculator
Find how long it takes to recover an investment once future cash flows are discounted to present value — the time-value-aware payback.
How it works
Find n where Σ [ CF ÷ (1 + r)^t ] ≥ initial cost, for t = 1 … n · fractional year interpolated
Ordinary payback counts raw cash flows until they equal the outlay, ignoring the time value of money. Discounted payback fixes that flaw by discounting each year’s inflow to present value before adding it up, so it always takes longer than plain payback. It tells you how many years the project needs before the discounted returns break even — a useful liquidity and risk check, though it still ignores cash arriving after the cutoff.
Worked example
A $10,000 machine returns $3,000 a year. Discounted at 8%, those inflows are worth $2,777.78, $2,572.02, $2,381.50, $2,205.09 … Cumulatively they reach $9,936.38 after four years and cross $10,000 partway through year five, so the discounted payback is about 4.03 years — versus a plain payback of 3.33 years.
Frequently asked questions
Why is discounted payback longer than regular payback?
Because each future inflow is worth less than its face value once discounted, it takes more years for the shrunken cash flows to add up to the original cost.
What are the limits of payback analysis?
Payback ignores every cash flow that arrives after the break-even point and gives no measure of overall profitability. Use it alongside NPV or IRR, which value the entire project life.
When does a project never pay back?
If the discount rate is high enough that the discounted inflows converge to a sum smaller than the initial cost, the cumulative total never reaches the outlay — the calculator flags this as “Never.”
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Educational estimate, not investment advice.