Investment Growth Calculator
Project how an investment could grow over time. Enter your starting amount, expected return, and monthly contributions — the calculator shows the nominal future value, the inflation-adjusted value in today's dollars, and the CAGR of your scenario, with preset return rates for quick comparisons. Everything runs in your browser; nothing is uploaded.
Past performance is not indicative of future results. The S&P 500 preset uses a long-run historical average (~10% nominal) for illustration only.
* With ongoing contributions, CAGR is an approximation of the average annual growth on total cash invested.
Year-end values. Solid line: nominal growth. Dashed line: purchasing power in today's dollars.
Assumes a fixed annual return, end-of-month contributions, and no taxes, fees, or withdrawals. Past performance is not indicative of future results. The S&P 500 preset uses a long-run historical average (~10% nominal) for illustration only. This calculator is for educational purposes only and does not constitute financial advice. Consult a qualified financial advisor before making decisions.
How to use this calculator
- Return preset — start from 7% (a conservative long-run assumption), 10% (the S&P 500's long-run historical average, shown for illustration only), or type your own rate. Past performance is not indicative of future results.
- Initial investment — the lump sum you invest today.
- Monthly contribution — optional recurring investments, added at the end of each month (dollar-cost averaging).
- Expected annual return — the average yearly growth you want to model. Try a lower number too — seeing both scenarios is the point.
- Years invested — the time horizon. Longer horizons let compounding do more of the work.
- Inflation adjustment — converts the future value into today's purchasing power, so a far-off number stays meaningful. A $25,937 balance in 10 years at 3% inflation spends like about $19,300 today.
- CAGR — the single constant yearly rate that would turn your total invested cash into the projected value. Useful for comparing scenarios apples-to-apples.
The formula behind it
Future value: the initial investment compounds annually, while monthly contributions form an ordinary annuity at the equivalent monthly rate i = (1 + r)1/12 − 1:
FV = P × (1 + r)t + PMT × (((1 + i)12t − 1) / i)
Inflation-adjusted value: Real = FV ÷ (1 + inflation)t
CAGR: (FV ÷ total invested)1/t − 1
Go deeper: How to Calculate CAGR: The Formula Every Investor Should Know and What Is a Good Annual Return? Historical Averages by Asset Class.
Frequently asked questions
What is CAGR and how is it calculated?
CAGR (Compound Annual Growth Rate) is the constant yearly rate that would grow a starting amount into the ending amount. The formula is CAGR = (ending value / beginning value)(1 / years) − 1. For example, $10,000 growing to $16,000 over 5 years is a CAGR of about 9.86%.
What is a good annual return?
There is no universal answer — it depends on the asset, the time period, and inflation. US stocks have averaged roughly 10% per year nominally over very long periods (about 7% after inflation); bonds have averaged less. Any historical average describes the past, not a promise about the future.
What is the difference between nominal and real returns?
The nominal return is the headline percentage your investment grows. The real return is what is left after inflation — approximately nominal return minus inflation. A 10% nominal return with 3% inflation is about a 7% real return, which is the number that reflects actual purchasing power.
Why does dollar-cost averaging work?
Dollar-cost averaging means investing a fixed amount on a schedule. When prices fall you automatically buy more shares, and when prices rise you buy fewer, which smooths out your average purchase price over time. It reduces timing risk but does not guarantee a profit or protect against losses in a falling market.
Lump sum vs. dollar-cost averaging — which is better?
Research (including a well-known Vanguard study) finds that investing a lump sum immediately has produced higher returns about two-thirds of the time, simply because markets rise more often than they fall. Dollar-cost averaging can still be preferable for peace of mind, since it limits the regret of investing everything right before a drop. The right choice depends on your temperament, not just the math.