What compounding frequencies are supported?

Monthly, quarterly, semi-annually, and annually — select what matches your account.

Does this account for inflation?

This calculator shows nominal returns. For real returns, you can manually adjust the rate to account for estimated inflation.

Compound Interest Calculator

Calculate the future value of an investment with compound interest and see a year-by-year growth schedule.

Enter details to calculate compound interest.

What This Calculator Does

Interest that compounds means you're earning interest on your interest, not just your original deposit, and the gap between compound and simple growth widens dramatically the longer money sits. This tool projects that growth for a single lump-sum principal — no ongoing contributions — across a term you choose, at monthly, quarterly, semi-annually, or annually compounding. The output includes both the final future value and a year-by-year table showing exactly how much interest accrued each year and how the balance built up.

How to Use It

Enter your starting principal, the annual interest rate as a percentage, and the number of years you plan to leave it invested, then pick a compounding frequency from the dropdown. Hit Calculate and the Calculation Summary shows your future value and total interest earned side by side with your original principal, while the Growth Schedule table underneath breaks the same numbers down year by year — useful for spotting how much of the eventual total comes from later years, once the balance is large enough for the compounding effect to really accelerate.

The Formula

This is the standard compound interest formula, A = P(1 + r/n)ⁿᵗ, where P is your principal, r is the annual rate as a decimal, n is the number of compounding periods per year (1 for annually, 2 for semi-annually, 4 for quarterly, 12 for monthly), and t is the number of years. Under the hood, the calculator doesn't just plug in the final numbers — it steps through the balance one compounding period at a time at full decimal precision, and only rounds to the nearest cent when it displays each year's row in the schedule. That means the running total never accumulates the small rounding errors that repeated per-period rounding would otherwise introduce, and the totalInterestEarned figure you see is exactly the future value minus your original principal.

A Worked Example

$1,000 invested at 5% annual interest for 10 years, compounded monthly, grows to $1,647.01 — $647.01 of that is interest, more than 64% on top of the original deposit, purely from the effect of compounding twelve times a year instead of once. Switch the scenario to annual compounding with a larger sum over a shorter window — $5,000 at 8% for 5 years — and the calculator returns $7,346.64, meaning $2,346.64 in interest. Notice the second example compounds far less frequently (once a year instead of twelve times) but still earns a larger interest total, simply because the rate and starting principal are both higher — a reminder that rate and principal typically matter more to your outcome than compounding frequency alone.

FAQ

What compounding frequencies are supported?: Monthly, quarterly, semi-annually, and annually — select what matches your account.
Does this account for inflation?: This calculator shows nominal returns. For real returns, you can manually adjust the rate to account for estimated inflation.