ROI / Payback Period Calculator
Compute simple ROI, annualised ROI and payback period.
Overview
Return on investment (ROI) and payback period are the two simplest yardsticks for evaluating any investment. ROI expresses the total gain as a percentage of the capital deployed; payback period reports how long it takes for cumulative cash flows to recover the original outlay. Together they tell you whether the project is profitable and how quickly it gets your money back. Neither captures the time value of money the way NPV or IRR do, but their simplicity is exactly why they remain dominant in operating decisions.
Annualized ROI normalises ROI across different holding periods so a one-year investment and a five-year investment can be compared. Simple ROI flatters long-held positions and disadvantages short trades; annualized ROI uses geometric mean growth to put both on a yearly basis. This calculator surfaces simple ROI, annualized ROI, and payback period together so the user can read the trade-off between "total return" and "time to recovery" in one view.
How it works
Simple ROI = (final_value − initial_investment) / initial_investment. Annualized ROI = (final_value / initial_investment)^(1/years) − 1 — equivalent to the compound annual growth rate (CAGR). Payback period for a single up-front investment with even annual returns is initial_investment / annual_cash_flow. For uneven streams, the tool walks the cash flow series and reports the year in which cumulative inflows first exceed the outflow, optionally interpolating to a fraction of a year.
Examples
- $10,000 invested, ends at $15,000 after 3 years: simple ROI = 50%, annualized ROI =
1.5^(1/3) − 1 ≈ 14.5%, payback ≈ 3 years if returns come at the end. - $50,000 marketing campaign producing $20,000 of attributable annual revenue: payback = 2.5 years, simple 3-year ROI = 20%, annualized ≈ 6.3% — break-even hits in year 3.
- $5,000 invested in a side business returning $1,000, $1,500, $2,000, $2,000 over 4 years: cumulative cash flows pass $5,000 during year 4. Simple ROI = 30%, annualized ≈ 6.8%, payback ≈ 3.25 years.
- A $1M factory upgrade saving $250k/year in labour: payback = 4 years; over a 10-year useful life simple ROI = 150% and annualized ≈ 9.6%.
FAQ
Does ROI account for the time value of money?
No. For longer projects or anything sensitive to discount rates, prefer NPV or IRR.
Is payback period a sufficient metric on its own?
Rarely — it ignores everything after the payback date. A 2-year payback on a project that dies in year 3 is worse than a 4-year payback on a 20-year stream.
How is annualized ROI different from average ROI?
Annualized ROI is geometric (compounding-aware). Averaging simple ROI overstates returns when there is volatility.
Should I use pre-tax or after-tax cash flows?
Be consistent. For investor-pitch comparisons use pre-tax; for personal decisions use after-tax.
What's a "good" ROI?
Compare against opportunity cost — the next-best alternative for the same capital. Below the risk-free rate is rarely worth pursuing.