Payback Period Calculator – How Long Until You Get Your Money Back?
The payback period answers the simplest question you can ask about an investment: how long until the cash it brings in covers what you put in? It works for a delivery van, a shop fit-out, solar panels, a heat pump, a software licence or a capital-budgeting homework problem. This calculator gives you both simple payback and discounted payback, checks them against your own cutoff, and shows what the payback period leaves out.
The payback period formula
When the cash coming back is the same every year, payback is just the investment divided by the annual cash flow:
Payback = Initial investment ÷ Cash flow per year
Spend 10,000 to save 2,500 a year and you are paid back in 10,000 ÷ 2,500 = 4 years. When the flows are uneven, keep a running total instead. Take a project costing 100,000 that returns 30,000, 40,000, 50,000 and 20,000:
| Year | Cash flow | Running total |
|---|---|---|
| 0 | −100,000 | −100,000 |
| 1 | 30,000 | −70,000 |
| 2 | 40,000 | −30,000 |
| 3 | 50,000 | 20,000 |
| 4 | 20,000 | 40,000 |
The total turns positive during year 3. At the start of that year you still need 30,000, and the year brings in 50,000, so payback is 2 + 30,000 ÷ 50,000 = 2.60 years, or about 2 years 7 months.
Discounted payback: why it takes longer
Simple payback treats 1 in year 3 the same as 1 today. Discounted payback first converts each future amount to today's money at your discount rate, CF ÷ (1 + r)^t, and then runs the same running total. At 10%, the example above pays back in 3.15 years instead of 2.60. When you spend first and earn later, discounted payback is always at least as long, and the gap widens as the rate rises. Push the rate high enough and the project never pays back within its life. For a normal project that rate is its internal rate of return.
Reading the cumulative cash chart
The main chart plots the running total over time. The shaded area below zero is the money still to recover; the area above zero is what you are ahead. Payback is where the line crosses zero for the last time. The dashed line is the same total in today's money, and the gap between the two lines is the cost of waiting. The band after payback marks cash that the payback period does not count at all.
Spread evenly or at the end of the year?
Textbooks assume cash arrives evenly through the year and interpolate, which gives answers like 2.60 years. If money really arrives in one lump at year end, such as an annual contract payment, payback can only be a whole number of years: 3 years in the example. Many calculators pick one without telling you, which is one reason their answers differ.
The blind spot: speed is not value
Payback ignores everything after the break-even point. Compare project A (−10,000, then 3,000 a year for six years) with project B (−10,000, then 5,000 a year for three years). B pays back in 2.00 years against A's 3.33, yet at 10% A has the higher NPV (3,065.78 vs 2,434.26) because it keeps paying after B has stopped. The Compare tab shows this side by side. Check the NPV and IRR before you decide.
When payback is the right lens
Payback matters most when cash is tight and you need your money back to fund the next thing, when technology changes fast enough that later years are uncertain, or when the later cash flows are simply risky. Companies set their own cutoffs, such as three or five years, based on those pressures. There is no universal "good" payback period.