Investing Calculators
Tools for growing money over time: model compound growth and recurring contributions, and measure how an investment performed with annualized-return and ROI math.
CAGR Calculator
Calculate the compound annual growth rate (CAGR) of an investment from its beginning value, ending value, and the number of years.
ROI Calculator
Calculate return on investment (ROI). Enter what you invested and what it is worth to see your net profit, ROI percentage, and annualized return.
Compound Interest Calculator
Free compound interest calculator. See how savings and investments grow with an initial amount, regular contributions, interest rate, and compounding frequency.
Inflation Calculator
Free inflation calculator. See what a dollar amount from one year is worth in another using U.S. CPI data, plus the total and average annual inflation.
Net Worth Calculator
Free net worth calculator. Add up your assets and subtract your debts to see your total net worth, the clearest single measure of financial health.
Rule of 72 Calculator
Use the Rule of 72 to estimate how long an investment takes to double, or the return needed to double in a set number of years.
Compounding is the whole engine
Investing works because returns earn returns. In the first year your money grows by whatever the market returns; in the second, both your original money and last year’s gains grow — and that stacking is what turns steady contributions into a large balance over decades. The catch is that it takes time, so the earlier a dollar goes in, the more of the work compounding does for you.
The compound-interest calculator makes this concrete: enter a starting amount, a monthly contribution, a rate, and a time horizon, and watch how much of the final balance is money you added versus growth the market provided. Over 20 or 30 years, the growth usually dwarfs the contributions — which is the entire argument for starting now rather than waiting for a bigger paycheck.
Measuring what a return actually was
A gain from $10,000 to $16,000 sounds like 60%, but that is meaningless without knowing how long it took. CAGR — the compound annual growth rate — collapses a multi-year result into a single yearly rate you can compare against anything else. It is the honest way to judge an investment, a fund, or your own portfolio, because it accounts for time rather than hiding it.
ROI answers a simpler question — how much you made relative to what you put in — and is useful for one-off decisions like a property or a project. The CAGR and ROI calculators cover both: use ROI for the headline and CAGR when you need to compare returns that played out over different lengths of time.
Inflation is the return you have to beat
A nominal return is the number on the statement; the real return is what is left after inflation eats its share. Money sitting in cash earning less than inflation is quietly losing purchasing power every year, even though the balance never drops. That gap is why long-term savings usually need to be invested rather than parked.
The inflation calculator shows what a sum today will be worth in the future — or what past dollars are worth now — so you can size goals in money that actually buys something. Pairing it with the growth tools keeps your projections honest: a 7% return against 3% inflation is really about 4% of true progress.
Guides & articles
Plain-English explainers to go with the calculators above — every figure tied to its source.
What Is the Average Stock Market Return?
You’ll hear “the market returns 10% a year.” It’s true on average — and misleading if you stop there. Here’s the real number, the inflation-adjusted number, and how to plan around both.
The Rule of 72: How to Double Your Money (with Table)
Divide 72 by your annual return and you get the years it takes to double your money. Here’s the formula, a ready-made table, and where the shortcut breaks down.
What Is a Good ROI? How to Calculate Return on Investment
ROI is simple to calculate and easy to misread. Here’s the formula, what a “good” return looks like, and the one adjustment that makes two investments actually comparable.