Legal

ROI & Payback Period Calculator

Legal basis: General capital-budgeting convention (return on investment, payback period, discounted payback); no statute governs these measures · checked 2026-10-04 · Rates and limits change — verify the current figures.

Return on investment, or ROI, answers the most basic question about any outlay: what did I get back relative to what I put in? The formula is (gain − cost) ÷ cost, so a $50,000 investment that returns $80,000 has a 60% ROI. It is quick and universally understood, which is exactly why it is so often misused: a 60% ROI over four years is a very different investment from 60% in six months, and a bare ROI figure does not say which one it is. The annualised ROI, computed as the yearly compound rate implied by the ratio of return to cost over the holding period, fixes that by putting different time spans on one scale.

Payback period answers the risk question instead of the return question: how long until the project returns its own cost? Simple payback is the initial cost divided by the annual net cash inflow, so a $50,000 outlay generating $20,000 a year pays back in 2.5 years. Managers like it because it is intuitive and it flags dangerous projects, those that tie up cash for years before returning it. Its weakness is that it ignores everything after the payback date, so a project that pays back slowly and then runs for decades looks worse than a quick-payback project that dies right after breaking even.

Both measures ignore the time value of money in their simple form, and a dollar received in year four is not worth a dollar today. The discounted payback period discounts each year's inflow at the rate you enter, accumulates the present values, and reports when they cover the cost. It is always longer than the simple payback, and the gap widens with high discount rates and back-loaded cash flows. Alongside it, the net present value of the inflow stream shows the estimated value created in today's dollars after recovering the cost.

Treat the output as an educational estimate for planning, not investment, tax or legal advice. The results assume the annual cash inflow arrives evenly and steadily, ignore taxes and financing, and depend entirely on the figures you enter; real projects have lumpy, uncertain cash flows, and tax treatment varies by jurisdiction and entity. Run sensitivities on the inputs and consult a qualified professional before committing capital.

Calculate

Total ROI(total value received − cost) ÷ cost60.0%

Annualised ROIcompound yearly rate over 4.00 years12.47%

Net gaintotal value received minus initial cost$30,000

Simple payback periodabout 2 years 6 months2.5 years

Discounted payback periodinflows discounted at 8.0% per year2.9 years

Extra time from discountingdiscounted payback minus simple payback0.4 years

NPV of inflowspresent value of 4 years of $20,000 inflows minus cost, at 8.0%$16,243

How the math works

ROI = (total value received − initial cost) ÷ initial cost, expressed as a percentage.
Annualised ROI = (total value ÷ initial cost) ^ (1 ÷ years) − 1, the compound yearly rate implied by the endpoints.
Simple payback = initial cost ÷ annual net cash inflow, shown in years with the month equivalent.
Discounted payback accumulates inflows discounted at (1 + rate) per year until the present values cover the initial cost; NPV is the sum of discounted inflows minus the cost.

Frequently asked questions

How do I calculate ROI?

Subtract the cost from the total value received and divide by the cost: ROI = (gain − cost) ÷ cost. Multiply by 100 for a percentage. A $50,000 investment that returns $80,000 has a 60% ROI.

Why also show an annualised ROI?

Because a raw ROI hides time. 60% in six months is exceptional, while 60% over four years is about 12.5% per year. Annualising turns the endpoint ratio into a compound yearly rate so different holding periods compare fairly.

What is the payback period?

The time an investment needs to return its own cost. Simple payback divides the initial cost by the annual net cash inflow; a $50,000 cost with $20,000 a year coming in pays back in 2.5 years.

What is discounted payback?

The same idea, but each future inflow is first discounted to present value at your chosen discount rate. Because future dollars count for less, discounted payback is always at least as long as simple payback, and it may never arrive if the discounted inflows never cover the cost.

What are the weaknesses of payback analysis?

It ignores everything after the break-even date, so long-lived projects look artificially bad, and the simple version ignores the time value of money entirely. Use it as a quick risk screen alongside NPV or annualised ROI rather than as the deciding measure.

Does this calculator handle uneven cash flows?

No. It assumes one steady annual inflow for the payback and NPV figures. If your project pays out unevenly, a spreadsheet with year-by-year rows, or a proper DCF model reviewed by a professional, is the right tool.

Are taxes included?

No. ROI, payback and NPV here are pre-tax measures based on the figures you enter, and tax treatment of gains, depreciation and entity type varies by jurisdiction. Consult a CPA for after-tax comparisons.

This calculator is an educational estimate for planning purposes only. It is not investment, tax or legal advice, the results depend entirely on the assumptions you enter, and tax treatment varies by jurisdiction and entity type. Consult a licensed attorney, CPA or qualified financial professional before committing capital.