Investing

Investment & ROI Calculator

Project the growth of your portfolio with regular contributions. Compare compounding frequencies and see your total return at a glance.

How the investment calculator works

Return on investment (ROI) measures how much your money has grown relative to what you originally put in. A 100% ROI means you doubled your money; a 50% ROI means your portfolio grew by half. This calculator combines a one-time initial deposit with recurring monthly contributions and compounds the total at the rate and frequency you choose, letting you see exactly how much of your final portfolio balance comes from your own contributions versus investment growth.

Monthly contributions matter more than most investors realize. Adding a fixed amount every month means your later contributions benefit from compounding for a shorter period, but your earlier contributions — and the gains they produce — are themselves reinvested and continue growing. This interplay between the timing of deposits and the compounding schedule is what makes the year-by-year chart so revealing: in early years, contributions dominate the balance; in later years, accumulated growth overtakes them.

The calculator reports two return figures: cumulative ROI and annualized return (CAGR). Cumulative ROI tells you the total percentage gain over the entire holding period. Annualized return converts that gain into a per-year equivalent, making it easy to compare against benchmarks like the S&P 500 or a savings account, regardless of how long you held the investment. Use both: cumulative to understand total wealth created, annualized to compare efficiency.

The formula

ROI and CAGR are calculated as follows:

ROI = (final value − total invested) / total invested × 100%

CAGR = (final value / total invested)^(1 / years) − 1

Where total invested = initial deposit + (monthly contribution × months)

In plain English: ROI divides your profit by your total cost and expresses it as a percentage. CAGR raises the ratio of final value to total cost to the power of one divided by the number of years, then subtracts one — effectively asking "at what constant annual rate would my money have had to grow to reach this result?" Both metrics ignore the timing of individual cash flows, which is why they work best for straightforward buy-and-hold or regular-contribution scenarios.

Worked example

Suppose you invest $5,000 upfront and add $300 per month for 20 years at an 8% annual return compounded monthly.

Total contributed: $5,000 + ($300 × 240 months) = $77,000
Final portfolio value: approximately $193,000
Investment growth (gain): approximately $116,000
Cumulative ROI: ($116,000 / $77,000) × 100 ≈ 151%
Annualized return (CAGR): roughly 8% per year

The key takeaway: you contributed $77,000 of your own money, but compounding turned that into $193,000 — more than $116,000 of the final balance came purely from reinvested growth. This is why starting early and staying invested through volatility is the most reliable wealth-building strategy available to ordinary investors.

When to use this calculator

Comparing investment options. Enter the same time horizon with different return rates to see the dollar difference between a 6%, 8%, or 10% annualized return.
Projecting retirement savings. Model your current savings balance as the initial deposit, your planned monthly contribution, and a target retirement date to see if you are on track.
Evaluating lump sum vs. monthly contributions. Set monthly contributions to zero for pure lump-sum scenarios, or set the initial amount to zero to see contributions-only growth.
Modeling different return scenarios. Use pessimistic (5%), base (8%), and optimistic (10%) return assumptions to understand your range of outcomes before committing capital.
Measuring past portfolio performance. Enter the actual amount you invested, the number of years held, and your ending balance to calculate the annualized return your portfolio has delivered.

Key concepts

ROI (Return on Investment): The total percentage gain on your investment: profit divided by total cost. Simple and intuitive, but does not account for how long the money was invested.
CAGR (Compound Annual Growth Rate): The annualized rate at which an investment would have grown at a constant pace to reach its ending value. The standard metric for comparing investments held for different lengths of time. Learn more about compound interest.
Real vs. nominal return: Nominal return is the raw percentage your investment grew. Real return subtracts inflation, giving you a sense of actual purchasing-power gain. With US inflation averaging around 3%, a 10% nominal return is roughly a 7% real return. See also: APR vs. APY.
Time horizon: The number of years you plan to stay invested. Longer horizons amplify the effect of compounding exponentially. Doubling your time horizon does not double your ending balance — it multiplies it by much more, because gains compound on gains.

Common mistakes

Ignoring taxes on gains. In taxable accounts, capital gains tax and dividend tax reduce your effective return. Model post-tax returns by subtracting your expected tax rate from the annual return input.
Cherry-picking favorable time windows. Reporting a 3-year return during a bull market inflates the apparent CAGR. Always compare investments over the same time period, or use full market cycles.
Forgetting expense ratios. A 1% annual fund fee does not sound like much, but on a 20-year horizon it can consume 15–20% of your ending balance. Subtract expense ratios from your expected return before modelling.
Comparing investments with different time horizons. A 150% ROI sounds better than a 50% ROI, but if the first took 30 years and the second took 5, the second had a far higher CAGR. Always annualize before comparing.
Confusing annualized and cumulative return. An investment that doubled in 10 years has a 100% cumulative return but only a 7.2% CAGR. Reporting the cumulative figure without the time context is misleading.

Frequently asked questions

What's a good ROI for investments?

It depends on the asset class and your risk tolerance. The S&P 500 has historically returned about 10% annually before inflation (roughly 7% after). A diversified portfolio targeting 6–9% annualized is considered solid for long-term investors. Anything above 15% consistently is exceptional and warrants scrutiny — higher returns almost always come with higher risk.

What's the difference between ROI and IRR?

ROI is a simple ratio of profit to cost. It tells you total gain but ignores when cash flows happened. IRR (internal rate of return) is the annualized discount rate that makes the net present value of all cash flows equal zero, so it properly accounts for the timing of each deposit and withdrawal. Use ROI and CAGR for straightforward buy-and-hold scenarios; use IRR when cash flows are irregular or the investment has multiple entry and exit points.

What's the difference between annualized and cumulative return?

Cumulative return is the total percentage gain over the whole holding period. A $10,000 investment that grows to $30,000 has a 200% cumulative return. Annualized return (CAGR) converts that into a per-year rate: 200% over 20 years is about 5.6% CAGR. Always use annualized figures when comparing two investments held for different durations — cumulative figures are misleading without the time context.

Does the calculator show pre-tax or post-tax returns?

The calculator shows nominal, pre-tax returns. In taxable accounts, gains are reduced by capital gains tax and dividend tax. In tax-advantaged accounts (401(k), IRA, Roth IRA), taxes are deferred or eliminated. To model after-tax growth in a taxable brokerage account, reduce your annual return input by your effective tax rate on investment income.

How do I adjust the result for inflation?

The calculator shows nominal values — future dollars that will have less purchasing power than today's. To estimate real (inflation-adjusted) growth, subtract expected inflation from your annual return before entering it. With US inflation averaging around 3%, entering 7% instead of 10% approximates a real return. Your resulting final value will be expressed in today's purchasing power.

Should I invest a lump sum or spread it out monthly?

Historically, lump-sum investing has outperformed dollar-cost averaging about two-thirds of the time because markets trend upward. However, monthly contributions reduce timing risk and are practical when you invest from a salary. They also enforce discipline by making investing automatic. This calculator models both: set monthly contribution to $0 for a pure lump sum, or set initial investment to $0 to model contributions only.

Related calculators

Disclaimer: This calculator is for informational and educational purposes only. Results are hypothetical projections based on a constant rate of return and do not account for taxes, fees, inflation, or market volatility. Past performance is not indicative of future results. Consult a qualified financial adviser before making investment decisions.