Payback Period Calculator

How This Calculator Works

Payback period is how long it takes an investment’s own cash flows to add up to what it originally cost — the simplest, most intuitive answer to “when do I get my money back?” Enter what you invested and either a single annual cash flow (if it’s the same every year) or a list of different cash flows per year, and this calculator finds the exact point, including the fraction of a year, where the running total catches up.

Payback period ignores the time value of money (a dollar next year is worth less than a dollar today) and anything that happens after the payback point — which is exactly why it’s usually used alongside, not instead of, a metric like ROI that accounts for the whole picture. Its appeal is simplicity: it directly answers a real, common question in plain terms.

The Formula

Uniform cash flow:

$$\text{Payback Period} = \frac{\vA{\text{Initial Investment}}}{\vB{\text{Annual Cash Flow}}}$$

Uneven cash flow: add each year’s cash flow to a running total until it reaches the investment, then interpolate the exact fraction of that final year:

$$\text{Payback Period} = \vC{\text{Full Years Elapsed}} + \left(\frac{\vD{\text{Remaining to Recover}}}{\text{That Year's Cash Flow}}\right)$$

Worked Example

An investment costing $10,000, returning $3,000, $4,000, $5,000, and $2,000 in years 1 through 4:

1. After year 1: $3,000 recovered — not enough yet.
2. After year 2: $7,000 recovered — still not enough.
3. During year 3: the running total reaches $12,000, crossing $10,000 partway through — with $3,000 still needed and $5,000 coming in that year, that’s $3{,}000 \div 5{,}000 = 0.6$ of the year.
4. Payback period: $2 \text{ full years} + 0.6 = 2.6 \text{ years}$.