Payback Period Calculator
How long an investment takes to repay itself, with fractional-year interpolation — plus the discounted payback period and a year-by-year cumulative table.
Payback Period Calculator: with the default inputs, payback period (years) is 4.17.
Everything you spend up front to get the cash flows started.
Used when inflows are the same every year. Net cash, not revenue.
How long the investment keeps producing. Used with a uniform inflow.
Used when inflows differ each year. Years 5–8 live under More options.
Your cost of capital. Used for the discounted payback and NPV.
When cumulative cash flow first reaches the initial investment.
- In plain terms
- 4 years and 2 months
- Discounted payback period (years)
- 5.28Same question, but each year's cash is discounted back to today first.
- NPV over the period
- $15,260
- Total cash recovered
- $60,000
- Net gain over the period
- $35,000
- Total return on the investment
- 140%
- Years modelled
- 10
Assumptions
- Cash flows arrive evenly through each year, which is what makes fractional-year interpolation valid.
- The initial investment is a single outlay at time zero.
- Inflows are net cash, excluding depreciation and other non-cash charges.
- Discounted payback uses end-of-year discounting at a constant rate.
| Year | Cash inflow | Cumulative | Discounted inflow | Cumulative discounted |
|---|---|---|---|---|
| 1 | $6,000 | -$19,000 | $5,556 | -$19,444 |
| 2 | $6,000 | -$13,000 | $5,144 | -$14,300 |
| 3 | $6,000 | -$7,000 | $4,763 | -$9,537 |
| 4 | $6,000 | -$1,000 | $4,410 | -$5,127 |
| 5 | $6,000 | $5,000 | $4,083 | -$1,044 |
| 6 | $6,000 | $11,000 | $3,781 | $2,737 |
| 7 | $6,000 | $17,000 | $3,501 | $6,238 |
| 8 | $6,000 | $23,000 | $3,242 | $9,480 |
| 9 | $6,000 | $29,000 | $3,001 | $12,481 |
| 10 | $6,000 | $35,000 | $2,779 | $15,260 |
Payback is the year where the cumulative column first turns positive, plus the fraction of that year needed to close the gap.
How this is worked out
The formula
Uniform inflows: payback = initial investment ÷ annual cash inflow
Uneven inflows: payback = (full years before recovery)
+ (amount still unrecovered ÷ that year's inflow)
Discounted payback: the same crossing, but each year's inflow is first divided by
(1 + discount rate)^year, so the recovery has to beat the cost of capital.Open How it’s calculated above to see this worked through with your own numbers.
What you enter
- Initial investment
- Everything you spend up front to get the cash flows started.in dollars · 0 or more · defaults to 25000
- Cash inflows are
- Choose one of 2 options.The same every year · Different each year
- Annual cash inflow
- Used when inflows are the same every year. Net cash, not revenue.in dollars · 0 or more · defaults to 6000
- Years to consider
- How long the investment keeps producing. Used with a uniform inflow.from 1 to 50 · whole numbers only · defaults to 10
- How many years of cash flow?
- Used when inflows differ each year. Years 5–8 live under More options.from 1 to 8 · whole numbers only · defaults to 5
- Year 1 cash inflow
- A number.in dollars · defaults to 8000
- Year 2 cash inflow
- A number.in dollars · defaults to 9000
- Year 3 cash inflow
- A number.in dollars · defaults to 10000
- Year 4 cash inflow
- A number.in dollars · defaults to 11000
- Year 5 cash inflow(under More options)
- A number.in dollars · defaults to 12000
- Year 6 cash inflow(under More options)
- A number.in dollars · defaults to 0
- Year 7 cash inflow(under More options)
- A number.in dollars · defaults to 0
- Year 8 cash inflow(under More options)
- A number.in dollars · defaults to 0
- Discount rate
- Your cost of capital. Used for the discounted payback and NPV.a percentage · from 0 to 100 · defaults to 8
What you get back
- Payback period (years)main answer
- When cumulative cash flow first reaches the initial investment.
- In plain terms
- Discounted payback period (years)
- Same question, but each year's cash is discounted back to today first.
- NPV over the period
- Total cash recovered
- Net gain over the period
- Total return on the investment
- Years modelled
What this assumes
- Cash flows arrive evenly through each year, which is what makes fractional-year interpolation valid.
- The initial investment is a single outlay at time zero.
- Inflows are net cash, excluding depreciation and other non-cash charges.
- Discounted payback uses end-of-year discounting at a constant rate.
About this calculator
Payback is the simplest capital-budgeting question there is: how long until the money comes back? It is the number every operator asks first, because it measures exposure — how long you are betting on forecasts before you're whole again.
How to use it
Enter what the project costs up front. If the cash it throws off is roughly the same each year — a solar array, an energy-efficiency retrofit, a machine with steady output — use the uniform mode and give the annual figure. If it ramps, switch to year-by-year and enter each year's net cash flow: revenue minus cash operating costs, not accounting profit. Depreciation is not a cash outflow and does not belong here.
Reading the results
- Payback period interpolates inside the final year, so $10,000 recovered at $2,500 a year is exactly 4.00 years, and a project that is $1,000 short entering year 5 with $4,000 of inflow that year pays back at 4.25.
- Discounted payback asks the harder question: how long until the discounted cash flow recovers the cost? It is always longer, and if the gap between the two is large, most of your recovery is coming from distant, uncertain cash. At an 8% discount rate, $10,000 at $2,500 a year takes 5.01 years discounted against 4.00 undiscounted.
- NPV over the period is the check on both. Payback can look fine on a project that destroys value.
What payback gets wrong
Every finance textbook lists the same two flaws, and both matter:
- It ignores everything after the break-even point. A project that pays back in 3 years and then dies scores better than one that pays back in 4 years and runs for 20. Payback is a liquidity measure, not a value measure.
- Plain payback ignores the time value of money entirely, treating a dollar in year 5 as equal to a dollar today. That's what the discounted version fixes, and it's why the discounted figure is the one to quote when the horizon is long.
Use payback as a screen and a risk gauge — "we're exposed for 3.4 years" — and use NPV or IRR to decide. When they disagree, NPV is right.
A worked example people actually run
A $25,000 rooftop solar system saving $6,000 a year pays back in 4.17 years undiscounted. At an 8% discount rate it takes about 5.3 years, and over the 25-year life of the panels the NPV is what justifies it — but the payback figure is what makes the decision feel safe, which is why it gets asked first.
Frequently asked questions
▸What is a good payback period?
It depends entirely on the asset's life and your risk tolerance. Manufacturers often want equipment to pay back in under 3 years; energy retrofits are financed at 7–10; infrastructure at 20+. The only universal rule is that payback must be comfortably shorter than the useful life.
▸How do you calculate payback with uneven cash flows?
Run a cumulative total until it turns positive, then interpolate: full years before recovery plus the amount still unrecovered divided by that year's inflow. The table on this page shows the running total so you can see the crossing.
▸What is discounted payback period?
The same calculation performed on discounted cash flows, so each year's inflow is divided by (1 + r)^year first. It is always longer than plain payback and answers whether the recovery beats your cost of capital, not just the nominal dollars.
▸Why do finance texts criticise payback?
Because it ignores all cash flow after the break-even point and, in its plain form, ignores the time value of money. A project with a fast payback and no tail can lose to a slower one with a long, profitable life. Use NPV to decide and payback to gauge exposure.
▸Should I use profit or cash flow?
Cash flow. Add back depreciation and other non-cash charges, and subtract capital spending needed to keep the asset running. Payback measures when cash returns, not when the income statement turns positive.
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The questions people ask next to a payback period.
Internal rate of return for up to 10 cash flows, solved by bisection — plus NPV at your discount rate, the NPV profile, and a warning when multiple IRRs exist.
Return on investment and annualized ROI from what you put in, what you got back and how long it took, with the work shown and ROI vs CAGR vs IRR explained.
What a future lump sum and a stream of payments are worth today at a given discount rate — with the discount factor, the annuity value and a period-by-period table.
Units and revenue needed to break even from fixed costs, price and variable cost per unit, plus contribution margin and a target-profit option.
Payment, true cost and debt-service coverage on a commercial or SBA loan — including guarantee fees and a compensating balance the bank makes you leave on deposit.