Compound Interest Calculator
Project your investment growth with regular contributions and compounding interest.
Result
Growth by Year
How to Use This Calculator
Enter your starting amount, any regular contribution and how often you make it, your expected annual interest rate, how many years you'll invest, and how often interest compounds.
How the Calculation Works
The balance grows every compounding period by the periodic interest rate, and your contributions are added on the schedule you choose. The bar chart shows the estimated balance at the end of each year.
Formula
Effective Monthly Rate = (1 + annual rate / compounding periods per year) ^ (compounding periods per year / 12) − 1
Balance compounds every month by this rate; contributions are added on your chosen schedule.
Example Calculation
$5,000 initial, $200/month, 7% annual rate compounded monthly, over 20 years grows to roughly $124,000, of which about $53,000 is contributions and the rest — around $71,000 — is interest earned.
Frequently Asked Questions
Does this account for taxes or fees?
No — this is a gross growth estimate before any taxes, account fees, or investment costs.
Why does compounding frequency matter?
More frequent compounding slightly increases growth for the same nominal annual rate, since interest starts earning interest sooner.
Related Tools
Disclaimer
Compound Interest Calculator: Visualize How Your Money Grows Over Time
"Compound interest calculator" is one of the most consistently searched personal-finance terms, largely because compounding is one of those concepts that's easy to state but hard to feel intuitively until you see actual numbers over a long timeline. This investment growth calculator lets you enter a starting balance, a recurring contribution, an expected annual rate, a time horizon, and a compounding frequency, then shows your projected final balance alongside a year-by-year growth chart.
A lot of basic "compound interest calculator with contributions" tools only handle a lump sum, which doesn't reflect how most people actually invest — through regular monthly or annual contributions to a 401(k), IRA, or brokerage account. This calculator supports both contribution schedules, so whether you're modeling a monthly automatic transfer or an annual lump-sum contribution, you can see how the combination of your own deposits and compounding growth builds your balance over years or decades.
Search terms like "compound interest calculator monthly" and "savings growth calculator" often come from people comparing a high-yield savings account against index fund investing, or deciding how aggressively to save for retirement. This tool lets you test different compounding frequencies — annually, semiannually, quarterly, monthly, or daily — to see how much (or how little) that choice actually moves your final balance for the same nominal rate, which is a useful way to cut through marketing language that emphasizes daily or continuous compounding as if it were dramatically better than monthly.
The growth chart included with this investment calculator breaks your projected balance down year by year, making it easy to see the compounding curve start to steepen in the later years of a long time horizon — often the most persuasive part of the whole exercise for anyone wondering whether it's "too late" to start investing. As with any projection, the results here are estimates based on a constant assumed rate of return; real markets fluctuate, and this tool doesn't account for taxes, investment fees, or inflation, so use it for planning and intuition-building rather than as a guarantee of future performance.
A common way to use this retirement savings calculator-style tool is to run the same time horizon twice with different monthly contribution amounts, to see concretely how much an extra $50 or $100 a month could mean decades from now. Seeing that difference as an actual dollar figure, rather than an abstract percentage, is often what turns a vague savings goal into a specific, actionable monthly target.