One Click Answers

OCACalculators

Share tool
FacebookPinterestEmail

Compound Interest Calculator

How much will my savings grow?

Enter what you start with, what you add and the rate, and see what your money could grow to.

One Click Answers · Compound Interest Calculator
oneclickanswers.com/compound-interest-calculator · Printed
About this tool & how to use it

What it does

See how much savings grow with compound interest and regular deposits, with a year-by-year table, a growth chart and a comparison of compounding frequencies.

How to use it

  1. Enter your starting amount, the yearly interest rate and the number of years.
  2. Choose how often interest is added (compounding) and, if you add money regularly, how much and how often.
  3. Read the final balance, what you put in and the interest earned.
  4. Press "Get a detailed answer" for the full working: tables, charts and what-if comparisons.

Money you add on a schedule. Leave blank for none.

One click answer

Your answer will appear here.

Fill in the form and your answer appears here as you type.

Related tools

Try another answer

Assumptions

  • The rate stays the same for the whole time. Real rates change.
  • Deposits are the same size each period and are made at the end of the period unless you choose the start.
  • Taxes, account fees and withdrawals are not counted.
  • Everything you enter is worked out in your browser and is never sent anywhere.

Printed from oneclickanswers.com. Results are estimates based on what was entered; see the assumptions above.

How we calculated this

Each time interest is added, your balance is multiplied by 1 plus the rate for that period. With 5% compounded monthly the monthly rate is 5% / 12 = 0.41667%, so each month the balance is multiplied by 1.0041667.

Interest then earns interest, which is why growth speeds up over time.

Every regular deposit is added at the end (or the start) of its period and then grows the same way for the rest of the time, so earlier deposits earn more than later ones. The page adds them up with the geometric-series formula, and the year-by-year table is the same calculation stopped at each year end.

APR and APY: the rate you type is the yearly rate before compounding (APR). The APY is what you really earn in a year once compounding is counted, so it is a little higher: 5% compounded monthly is 5.116%. An assumed investment return is a different thing: a guess, not a rate a bank promises.

Formulas and details
  • Balance after t years with n compoundings a year = start x (1 + rate / n)^(n x t), plus each deposit grown the same way.
  • Deposits, m per year, each d: d x (q^N - 1) / (q - 1), with q = (1 + rate / n)^(n / m) and N = m x t (multiplied by q when deposits are at the start of the period).
  • APY = (1 + rate / n)^n - 1.

Assumptions

  • The rate stays the same for the whole time. Real rates change.
  • Deposits are the same size each period and are made at the end of the period unless you choose the start.
  • Taxes, account fees and withdrawals are not counted.
  • Everything you enter is worked out in your browser and is never sent anywhere.

Common mistakes

  • Typing the APY where the page asks for the yearly rate. Enter the rate before compounding (the APR); the page then shows the APY, which is a little higher.
  • Treating the answer as a promise. The page holds the rate the same for the whole time, and real savings rates change; an investment return is only an assumption.
  • Forgetting what is left out. Taxes, account fees and withdrawals are not counted, so what you keep can be less.
  • Choosing deposits at the start of each period when your account adds them at the end. A deposit at the start earns one more period of interest, so the result comes out higher; end of period is the cautious choice.

Example

Input: $10,000 to start, $100 added each month at the end of the month, 5% a year compounded monthly, for 10 years

Result: After 10 years you would have about $31,998.32: you put in $22,000.00 and earn about $9,998.32 in interest.

Questions

What is the difference between compounding monthly and daily?

More frequent compounding adds interest to the balance more often, so it earns slightly more. The detailed answer shows your numbers at every frequency so you can see how small or large the difference is.

Should deposits be at the start or the end of the month?

A deposit at the start of a period earns one more period of interest than one at the end. Your bank statement shows which fits your account; end of period is the cautious choice.

Is this the same as an investment calculator?

The arithmetic is the same, but an investment return is only an assumption. The Investment Growth Calculator labels its answer as a projection and adds inflation and other-return comparisons.

Last reviewed 2026-10-20. Report an incorrect result

Got another question?

Free, no account. Answers show how they were worked out.