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Watch what consistent saving actually does

Compounding is the most important idea in long-term investing — and the easiest to underestimate in the abstract. Put in your numbers and see the balance, the growth, and the year-by-year table for yourself.

Your investment inputs

Model any goal — retirement, education, a property. Same math, different horizon.

Initial investment ($)

What you'd invest right away. 0 if you're starting from scratch.

Monthly contribution ($/month)

The amount added each month, for the full period.

Expected annual return: 6%

A planning assumption, compounded monthly. Higher expected returns come with higher volatility — the chart shows the arithmetic, not a promise. See our guide to compound interest for what the long run has historically looked like.

Number of years

Time is the biggest variable here — try 10, 20, and 30 to feel it.

Your projection

Runs instantly in your browser — nothing is sent or stored.

Enter your inputs and press "Calculate growth" to see your final balance, growth breakdown, chart, and year-by-year table.

Assumptions behind this projection

Annual return compounded monthly, applied every period
Contributions are level and start in month one
Taxes, fees, and inflation are not modeled
The return is an assumption, not a forecast or a guarantee

This is an educational estimate, not investment advice or a guarantee of returns. All investing involves risk, including loss of principal, and past performance never guarantees future results. Real portfolios fluctuate; this chart shows a smooth assumption for clarity.

Discuss a real investment plan

Understanding the result

Why the second half grows faster

Look at the table, not just the total: in the early years, most of the balance is what you put in. In the later years, most of it is growth earning its own growth — that's compounding. Two levers matter most: time (the longest you have is the asset you can't buy back) and consistency (the contributions keep feeding the machine through up years and down years). The full discussion of how this works over a career, including the risk that comes with the return, lives in our investment planning guide.