Free Compound Interest Calculator - Investment Growth with Contributions

A That shouldn't happen unless you set a negative interest rate. The chart always climbs if your rate stays positive and you keep contributing. But if you stop adding money and the rate is very low, growth can look flat. Try entering 1% with a $0 monthly contribution on a $1,000 initial investment—you'll see barely any movement. For realistic results, use rates between 4% and 10% for stocks or 2% to 5% for bonds.

A You can project up to 50 years with this calculator. That's enough to see how a 25-year-old's retirement savings might grow until age 75. For example, a $10,000 start at 7% with $500 monthly contributions yields over $2.3 million after 50 years. The chart handles up to 600 months of data easily. One practical tip: keep your projections realistic by not using overly optimistic rates beyond 10%.

A Compounding frequency directly impacts how often interest gets added to your principal. Monthly compounding adds interest 12 times per year, while annual compounding only adds it once. On a $10,000 investment at 6% over 20 years with $200 monthly contributions, monthly compounding earns roughly $4,200 more than annual compounding. The calculator automatically updates the chart and totals when you change this setting. Try switching from annual to daily and watch the interest earned jump.

A This calculator shows nominal returns, not inflation-adjusted numbers. A 7% return looks great on screen, but subtract 3% for inflation and your real purchasing power grows closer to 4%. For a rough inflation-adjusted estimate, just lower your interest rate by 2-3%. Try comparing a 7% run versus a 4% run on a $50,000 portfolio over 30 years—you'll see a massive difference in what that money actually buys.

A This calculator assumes you keep every dollar invested for the full term. If you plan to withdraw early, subtract that amount from your monthly contribution or initial deposit. For example, a $10,000 withdrawal in year 5 on a 20-year plan means you'd recalculate with $10,000 less starting principal. The chart won't show dips for withdrawals, so you'll need to run two separate projections. That's the honest way to see the impact on your final balance.

A This calculator doesn't have a built-in export button, but you can screenshot the chart and totals for quick sharing. For saving your exact inputs, just jot down the principal, rate, monthly contribution, and years—that's all you need to recreate the projection later. If you're a freelancer comparing project rates, run two side-by-side scenarios and capture both images. One tip: use your browser's print-to-PDF option if you want a clean, scrollable record of the results.

A Real markets don't move in straight lines, but this tool locks in one rate for the whole run. That's actually a feature for planning: you can test a worst-case 3% scenario against an optimistic 9% one in under a minute. For a $30,000 portfolio with $400 monthly deposits over 25 years, the difference between those rates is roughly $400,000. Just remember the chart is a straight-line projection, not a promise. Use it to compare strategies, not to predict your exact retirement balance.

A Screen rotation helps when viewing 30-year projections on smaller smartphone screens. Turning your phone sideways lets the chart display all columns without clipping. On a standard iPhone, landscape mode reveals the exact year-by-year breakdown underneath the interactive bars. Try this layout trick if you're reviewing portfolio milestones while commuting.

A This calculator projects gross returns, meaning taxes aren't deducted from your final balance. Uncle Sam takes a cut if you use a taxable brokerage account rather than a Roth IRA. Suppose your $50,000 portfolio generates $20,000 in gains over 15 years. You'll owe capital gains tax on that profit unless the money sits in a tax-advantaged vehicle. Try lowering your expected rate slightly to simulate tax drag when planning long-term goals.

A Halting contributions for a year or two won't destroy your entire portfolio, but it does leave money on the table. Suppose you invest $500 monthly at 7% for 20 years, then pause deposits for 24 months. You miss out on roughly $13,000 in fresh principal and the compounding it would have generated. Try running two scenarios to see the gap yourself. A quick restart usually gets your retirement train back on schedule.