Investment return calculator: ROI, payback period, and NPV
This investment return calculator computes three metrics from the same inputs: annual ROI (how much you earn per dollar invested per year), payback period (how many years until the investment breaks even), and NPV (the present value of all future returns discounted to today). Use any one or all three depending on how your business evaluates capital decisions.
Return on investment (ROI)
Annual ROI = annual net benefit ÷ initial investment
ROI measures what you get back relative to what you put in. An annual ROI of 40% means the investment returns 40 cents for every dollar invested, per year. ROI does not account for the time value of money — a dollar today is worth more than a dollar three years from now — which is why NPV exists.
Payback period
Payback period = initial investment ÷ annual net benefit
The payback period is the number of years (or months) until the cumulative net benefit equals the upfront cost. It is the simplest measure of investment risk: a shorter payback period means the money comes back faster and is exposed to fewer years of uncertainty.
Net present value (NPV)
NPV = PV(annual benefit stream) − initial investment
NPV discounts future cash flows at your cost of capital (the discount rate) to reflect that money received in the future is worth less than money today. A positive NPV means the investment exceeds your hurdle rate and creates value. A negative NPV means the investment earns less than your cost of capital — even if the undiscounted total return is positive.
The discount rate is typically the weighted average cost of capital (WACC) for large companies, or the interest rate on a business loan for a small business evaluating a single investment. Common small business hurdle rates range from 8% to 20%.
Annual net benefit: what to include
The annual net benefit is the increase in profit the investment produces each year — not just revenue. It should include:
- Revenue gains (new sales enabled by the investment)
- Cost savings (labor, materials, energy, waste reduction)
- Minus: any new ongoing operating costs (maintenance, subscriptions, added staff)
Do not include the initial investment itself, depreciation, or financing costs — those are captured in the investment amount and the discount rate respectively.
Worked examples
Example 1 — delivery van: A plumber buys a second delivery van for $35,000. The van enables two additional jobs per day at $200 net profit each, or roughly $48,000 per year (240 working days × $200). The van's useful life is 7 years. The business's cost of capital is 10%.
| Metric | Value |
|---|---|
| Annual ROI | $48,000 ÷ $35,000 = 137% |
| Payback period | $35,000 ÷ $48,000 = 8.75 months |
| Total net benefit (7yr) | ($48,000 × 7) − $35,000 = $301,000 |
| NPV at 10% | $48,000 × 4.868 − $35,000 ≈ $198,600 |
An 8.75-month payback and strong positive NPV make this an easy decision. The 7-year life assumption is conservative — a well-maintained van could last 10+ years.
Example 2 — CRM software: A roofing company pays $8,400/year ($700/month) for a CRM system. They estimate it saves 10 hours/week of admin work (at $25/hour) and improves close rate enough to generate $15,000/year in additional revenue. Net annual benefit: $10,000 (labor savings) + $15,000 (revenue) − $8,400 (subscription) = $16,600.
| Metric | Value |
|---|---|
| Initial investment | $0 (SaaS — no upfront cost) |
For zero-upfront SaaS, the ROI calculation does not apply as written. Instead, compare the annual net benefit ($16,600) to the annual cost ($8,400): the software returns nearly $2 for every $1 spent annually. For tools with an upfront fee — onboarding, implementation, hardware — use that fee as the investment and treat the first year's subscription as part of ongoing operating cost, deducted from the annual benefit.
Example 3 — marginal investment: A restaurant buys a $20,000 automated dishwasher that saves $5,000/year in labor. Useful life is 10 years; hurdle rate is 12%.
| Metric | Value |
|---|---|
| Payback period | 4 years |
| Total net benefit (10yr) | $30,000 |
| NPV at 12% | $5,000 × 5.65 − $20,000 ≈ $8,250 |
A positive NPV at 12% means the investment earns more than the hurdle rate. But the 4-year payback means the restaurant is exposed to 4 years of risk before breaking even — if labor costs change or the machine needs major repairs, the actual return may differ.
Assumptions and limitations
- Annual benefit is assumed constant. The calculator uses the same annual net benefit for every year of the useful life. In reality, benefits may ramp up over time (staff learning curve), decline (aging equipment), or vary seasonally. For investments with uneven returns, a full discounted cash flow (DCF) model is more appropriate.
- No terminal value or salvage value. At the end of the useful life, some investments retain value — a vehicle can be sold, a building can be resold. This calculator does not model salvage value. If the investment has significant residual value, the true NPV is higher than shown.
- No taxes. The benefit and investment figures should be pre-tax or after-tax consistently. Section 179 and bonus depreciation can effectively reduce the initial investment for tax purposes — see the Section 179 vehicle deduction calculator and the equipment lease vs. buy calculator for tax-adjusted comparisons.
Frequently asked questions
- What is a good ROI for a small business investment?
- It depends on the risk and your cost of capital. A safe, low-risk investment (buying a piece of equipment with a proven ROI track record) might only need to beat 8–10%. A riskier investment — entering a new market, developing a new product — might require a 25–30% hurdle rate to justify the uncertainty. As a rule of thumb, any investment with a payback period shorter than its useful life and a positive NPV at your cost of capital is worth doing.
- Should I use ROI or NPV to evaluate an investment?
- Use both. ROI and payback period are fast and intuitive — they tell you how profitable and how quickly you recoup the investment. NPV is more rigorous because it accounts for the time value of money and your hurdle rate. An investment can show a strong ROI but a negative NPV if the returns come too slowly relative to your cost of capital. For any significant purchase, check that NPV is positive before committing.
- What discount rate should I use?
- Use the interest rate you would pay to finance the investment, or your target return on capital. If you are taking out a business loan at 9% to fund the purchase, 9% is a reasonable discount rate — the investment must at least beat the borrowing cost. If you have equity capital with a higher expected return, use that rate instead. Most small businesses use 8–15%.
- How do I estimate annual net benefit?
- Be conservative. Identify every cost the investment will reduce (labor hours × hourly rate, material waste reduction, fewer repairs) and every incremental revenue it will generate (additional clients × average revenue). Then subtract new ongoing costs (maintenance contracts, consumables, additional insurance). Test your assumptions at 50% of your estimate — if the investment still has a positive NPV at half the expected benefit, it is a robust decision.
Sources
- Investopedia — "Return on Investment (ROI): How to Calculate It and What It Means" (accessed 2026-10-04)
- Corporate Finance Institute — "Net Present Value (NPV)" (accessed 2026-10-04)