Payback Period Calculator

Find how long an investment takes to pay for itself, with simple and discounted payback for even or uneven cash flows, NPV and a year-by-year cumulative table.

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About this tool

What is the Payback Period Calculator?

Enter the up-front cost and the cash the investment brings in each year (or month), and this calculator finds the payback period: how long until the money you put in comes back. It works for even cash flows, where you type one amount and a number of periods, and for uneven ones, where you paste a list such as 30000, 40000, 50000.

Alongside the simple payback it gives the discounted payback, which counts each future amount at its present value using your discount rate. That answers a stricter question: how long until the investment has repaid its cost and the return you could have earned elsewhere. The net present value and a cumulative table and chart show what happens after payback too.

Answers are given in periods and, for yearly flows, in years and months, so 2.6 reads as 2 years 7 months. Inputs are kept in the page address so you can share a scenario by link.

  • Simple and discounted payback with interpolation
  • Even, growing or uneven cash flows
  • Years and months or monthly periods
  • NPV, net cash and a cumulative chart
  • Warning when the balance turns negative again
  • Shareable link and copyable summary
Read the guide: Payback Period Formula: Simple, Discounted and Uneven Cash Flows

How to use the Payback Period Calculator

  1. Enter the initial investment as a positive number.
  2. Choose uneven or even cash flows. For uneven, list each period's net cash flow; for even, give the amount, the number of periods and any growth rate.
  3. Set the discount rate per period, usually your cost of capital or hurdle rate, and choose years or months.
  4. Read the simple and discounted payback, the NPV and the net cash.
  5. Check the table and chart. A warning appears if the running balance turns negative again after payback, for example because of a later overhaul.

Worked examples

Uneven cash flows

Input

Investment 100,000; flows 30,000, 40,000, 50,000, 20,000; rate 10%

Output

Simple 2.6 years; discounted 3.15 years; NPV 11,556.59

After two years 70,000 is back and 30,000 remains. Year 3 brings 50,000, so payback is 2 + 30,000 / 50,000 = 2.6. Discounted, the first three years return 97,896.32, and year 4 is worth 13,660.27, giving 3 + 2,103.68 / 13,660.27 = 3.154.

Even savings from equipment

Input

Investment 50,000; 12,500 a year for 6 years; rate 0%

Output

4.0 years

With even flows the answer is simply 50,000 / 12,500.

Never recovered

Input

Investment 100; flows 10, 10

Output

Not recovered

The cumulative balance stays at -80, so there is no payback within the periods given.

Background and insight

Simple payback with even flows is investment / annual cash flow: a 50,000 machine that saves 12,500 a year pays back in 4 years. With uneven flows you add up the cash year by year until the running total covers the investment, then interpolate within the recovery year: payback = years before recovery + unrecovered amount / cash flow in the recovery year. The interpolation assumes the cash arrives evenly through that year, which is the standard textbook convention.

Discounted payback divides each year's flow by (1 + r)^t before adding it up. Because later money is worth less, the discounted payback is always longer than the simple one when the rate is positive, and some projects that pay back on a simple basis never do once discounted. If the discounted payback exists within the project's life, the NPV over that life is positive.

Payback is popular because it is easy to explain and favours projects that return cash quickly, which matters when cash is tight or the technology may be obsolete soon. Its weaknesses are well known: simple payback ignores the time value of money, and both versions ignore everything after the payback date, so a project with large late returns can look worse than a quick but small one. Use it with NPV or IRR rather than instead of them.

Common use cases

  • Equipment and machinery

    Check how quickly a new machine, vehicle or tool pays for itself from savings or extra output.

  • Energy upgrades

    Compare insulation, LED lighting or heat pumps by how many years of savings repay them.

  • Software and automation

    Weigh a subscription or build cost against hours saved each month.

  • Capital budgeting screens

    Apply a maximum payback rule before a full NPV or IRR review.

  • Small business purchases

    Decide whether a marketing campaign, new hire or shop fit-out returns cash soon enough.

Tips and limitations

  • Use net cash flows: extra revenue or savings minus the running costs the investment adds, after tax if you want an after-tax payback.
  • Match the rate to the period. If you enter monthly cash flows, use a monthly discount rate (roughly the annual rate / 12).
  • Watch the flows after payback. Two projects with the same payback can have very different NPVs.
  • Include later outflows such as overhauls or replacement parts as negative numbers. The tool flags a balance that falls back below zero.
  • There is no universal good payback period. Many businesses look for two to three years on equipment and accept longer for buildings; compare with the asset's useful life.

Frequently asked questions

What is the payback period formula for uneven cash flows?

Add the cash flows year by year until the total covers the investment. Payback = years before full recovery + unrecovered amount at the start of the recovery year / cash flow in that year.

What is the difference between simple and discounted payback?

Simple payback adds cash flows at face value. Discounted payback first divides each one by (1 + r)^t, so later money counts for less. Discounted payback is longer whenever the rate is positive.

How do I turn 2.6 years into years and months?

Multiply the fraction by 12: 0.6 x 12 = 7.2, so 2.6 years is about 2 years 7 months. The calculator shows both.

Why is payback not enough to judge an investment?

It ignores cash after the payback date, and simple payback ignores the time value of money. Use it as a liquidity and risk check alongside NPV or IRR.

What discount rate should I use?

Your cost of capital or the return you require from projects of similar risk. Many small businesses use their borrowing rate plus a margin.

Can cash flows be negative?

Yes. Type -5000 or (5000) for an outflow in a later year. If the running total drops below zero after payback, the tool warns you.

Is there an in-depth guide to the Payback Period Calculator?

Yes. “Payback Period Formula: Simple, Discounted and Uneven Cash Flows” covers the background, how it works, common pitfalls and worked examples. Read the full guide.

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