Payback Period Calculator

What payback period measures

How long until cumulative cash inflows equal the initial outlay. An investment of 50,000 returning 15,000 a year pays back in three years and four months. It is popular because it is immediately understandable and answers the question people actually ask about a proposal, which is how long before this stops being a hole in the budget.

Two serious blind spots

It ignores everything after payback. A project paying back in three years then producing nothing scores identically to one paying back in three years and producing for twenty more. Ranking proposals by payback alone systematically favours short-lived projects over valuable ones.

It also ignores the time value of money in its simple form. Cash received in year four is treated as equal to cash received in year one, which it is not.

Discounted payback

Discounting each year's cash flow before accumulating fixes the second problem and produces a longer, more honest period. It does not fix the first. Discounted payback is the better of the two and still should not be the deciding metric on its own.

Use it as a risk filter, not a ranking

Payback is genuinely good at one thing: expressing exposure. A short payback means capital is at risk for less time, which matters when the future is uncertain, technology moves quickly, or the business needs liquidity. Used as a threshold, rejecting anything beyond a certain period, it is sensible. Used to choose between proposals that both clear the threshold, it is misleading. Rank on net present value or internal rate of return and use payback as a constraint alongside them.

Uneven cash flows

Where inflows vary year to year, accumulate them until the total crosses the outlay and interpolate within the final year. Beware projects with negative cash flows partway through, such as a mid-life overhaul, since the cumulative total can cross zero more than once and the simple reading of payback becomes ambiguous.