Payback Period Calculator
Inputs
Equal annual equipment savings demonstrate the default simple and discounted payback calculation.
Payback Results
Simple payback detail
- Status
- Not calculated
No target set.
Discounted payback detail
- Status
- Not calculated
No target set.
Discounted payback is normally more conservative because future cash flows are reduced to present value.
The data table below is the accessible alternative to the chart.
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Cash Flow Table
On a small screen, swipe sideways to see every column. The period column stays pinned.
| Period | Cash Flow (£) | Discounted Cash Flow (£) | Cumulative (£) | Cumulative Discounted (£) |
|---|
How to Use the Payback Period Calculator
- Enter the time-zero investment and choose a display currency.
- Select annual or monthly timing, then use equal inflows or editable uneven period rows.
- Enter an annual discount rate and, if useful, a maximum acceptable payback target.
- Select Calculate Payback. Review both recovery methods, ambiguity warnings, chart, and data table.
Currency changes presentation only: the payback period is unchanged when every amount uses the same currency.
Payback Period Formulas and Assumptions
Equal cash flows: Payback period = I ÷ C.
Uneven cash flows: Payback period = n + U ÷ Cn+1.
Discounted cash flow: DCFk = CFk ÷ (1 + r)k.
Discounted payback: n + Ud ÷ DCFn+1, where cumulative discounted cash flow first reaches zero in period n + 1.
Annual-to-monthly rate: rmonthly = (1 + rannual)1/12 − 1.
I is the initial investment; C is an equal net inflow; CFk is period k's net cash flow; DCFk is its present value; r is the rate per period; n is the last fully unrecovered period; and U or Ud is the positive amount still unrecovered after that period.
Assumptions: the initial investment occurs at time zero; later cash flows occur at period end; every entered amount is a net cash flow in one consistent currency; and fractional periods use linear interpolation, which assumes the recovery-period cash flow accrues evenly within that period.
Worked Example Using the Default Values
With an initial investment of 10,000, annual net inflows of 2,500, and a 5% annual discount rate, simple payback is 10,000 ÷ 2,500 = 4.00 years.
| Year | Net cash flow | Discounted cash flow | Cumulative discounted balance |
|---|---|---|---|
| 0 | −10,000.00 | −10,000.00 | −10,000.00 |
| 1 | 2,500.00 | 2,380.95 | −7,619.05 |
| 2 | 2,500.00 | 2,267.57 | −5,351.47 |
| 3 | 2,500.00 | 2,159.59 | −3,191.88 |
| 4 | 2,500.00 | 2,056.76 | −1,135.12 |
| 5 | 2,500.00 | 1,958.82 | 823.70 |
The discounted total crosses zero during year 5. Interpolation gives 4 + 1,135.12 ÷ 1,958.82 = 4.58 years, approximately 4 years 7 months.
Compact uneven-cash-flow example
For an investment of 10,000 and inflows of 2,000, 3,000, 4,000, and 3,500, 1,000 remains after year 3. Payback is years before recovery + unrecovered amount ÷ next period's cash flow = 3 + 1,000 ÷ 3,500 = 3.29 years.
How to Interpret Payback
Simple vs discounted payback
Simple payback is a quick liquidity screen. Discounted payback recognises the time value of money and is normally longer at a positive rate. A target can make either result actionable, but the cutoff should reflect project risk, liquidity needs, and asset life.
When payback can mislead
Payback ignores all cash flows after recovery, so two projects with very different long-term value can have the same answer. It also rewards front-loaded cash flows. Compare it with NPV or IRR for a fuller investment decision.
Negative and non-conventional cash flows
Later outflows can make cumulative cash flow cross zero more than once. This calculator distinguishes the first crossing from sustained recovery within the entered analysis. If recovery is later reversed, treat the payback metric as ambiguous and examine the full table and NPV.
Monthly conversion
The calculator derives an effective monthly rate using (1+r)1/12−1. This is more internally consistent than simply dividing an effective annual rate by 12.
Methodology and Review
Author and reviewer: Starlight Tools financial-calculator editorial team, specialising in financial formula implementation and client-side numerical testing. Last reviewed: 14 July 2026.
The implementation starts with the time-zero outlay, accumulates net period-end cash flows with and without discounting, linearly interpolates a crossing within a period, and separately checks whether recovery remains sustained through the final row. Tests cover equal, uneven, negative, monthly, target, zero-rate, and no-payback cases.
Method references: ACCA: payback and discounted payback and IFRS Foundation: IAS 7 Statement of Cash Flows.
This calculator is an educational decision aid, not financial advice. Use assumptions appropriate to your project and review material decisions with a qualified professional.
Payback Period FAQ
What is a payback period?
The payback period is the time needed for cumulative net cash inflows to recover the initial investment. Payback time is a common synonym.
What is the difference between simple and discounted payback?
Simple payback adds cash flows at face value. Discounted payback first reduces each future cash flow to present value, so it is normally the same or longer when the discount rate is positive.
How is discounted payback calculated?
Each period's net cash flow is divided by (1 + the per-period discount rate) raised to the period number. The discounted values are accumulated from the initial outlay, and linear interpolation estimates any fractional recovery period.
Can payback be calculated with uneven or negative cash flows?
Yes. Enter an editable row for every period. Negative values are treated as additional outflows. If the cumulative balance recovers and later becomes negative again, the calculator reports both first and sustained payback and warns that interpretation is ambiguous.
What does no payback within the analysis mean?
It means the cumulative cash flow has not recovered the initial investment by the last entered period. It does not prove that recovery can never occur after the selected analysis ends.
How should I choose a discount rate?
Use a rate consistent with the timing, risk and type of cash flows, often an organisation's project-specific opportunity cost of capital. Test more than one rate when the estimate is uncertain.
Can I calculate monthly payback?
Yes. Select Monthly. The calculator converts the entered effective annual rate to a monthly rate using (1 + annual rate)^(1/12) - 1 and reports both months and a years-and-months equivalent.
Should depreciation or financing costs be included?
Enter net cash flows, not accounting profit, so non-cash depreciation is excluded. Include financing cash flows only when your decision framework intentionally measures cash flow after financing; otherwise keep project and financing analysis separate.
What is an acceptable payback period?
There is no universal cutoff. Set a target that reflects liquidity needs, project risk, asset life and company policy, then compare both simple and discounted payback with that target.
Why is payback different from break-even and ROI?
Payback measures how long cumulative cash flow takes to recover an outlay. Accounting break-even concerns revenue and costs at a volume or time, while ROI compares a return with the investment and does not itself show recovery timing.
Why is payback different from NPV and IRR?
Payback focuses on recovery time and ignores cash flows after recovery. NPV measures value added in currency terms across the full analysis, while IRR estimates the discount rate at which NPV equals zero.