Payback Period Calculator
Simple and discounted payback from uniform or listed cash flows, the fraction of the period interpolated, the cumulative table, NPV and profitability index.
The period in which the outlay is recovered (simple, and discounted at your rate), the cumulative and discounted cumulative for every period, NPV, the profitability index and the total return over the horizon.
Example: 10 000 returning 3 000 a year: simple payback 3.33 years; at 10 % the discounted payback is 4.26 years and the five-year NPV 1 372.36 (profitability index 1.14).
When the outlay comes back,
with and without discounting.
How the payback is interpolated, what discounting changes, and why NPV is shown next to it.
Simple payback
The cumulative inflow is tracked period by period against the initial outlay. Payback is the number of full periods before the cumulative turns non-negative plus the fraction of the next period needed: shortfall ÷ that period's inflow, assuming the flow arrives evenly through the period. Flows can be the same amount every period or a list typed one per period (a negative entry is an outflow that period).
Discounted payback and NPV
At a discount rate per period each flow is divided by (1 + r)ᵗ (end-of-period convention) before accumulating, which gives the discounted payback; NPV is the sum of discounted flows less the outlay and the profitability index is their ratio. Payback ignores everything after the crossing, which is why NPV is shown alongside: a project can pay back quickly and still be worth less than another.
What it is not
Arithmetic on the numbers you type: the rate, the flows and the horizon are all yours and nothing is forecast. It is not investment or financial advice. Nothing leaves the browser; the same four anonymous usage counts as the rest of the site apply.
SOURCES
- Simple payback = periods before the cumulative turns positive + shortfall ÷ that period’s flow; discounted flow = flow ÷ (1 + r)ᵗ, end of period; NPV = Σ discounted − investment; PI = PV ÷ investment
Last reviewed 22 September 2026. How results are checked: How we verify.