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Savings growth over time

Compound Interest Calculator

See how a starting balance and recurring deposits grow with compound interest. Contributions are added at the end of each period.

Your numbers

Compound interest

Starting amount, rate, and optional deposits. Deposits are added at the end of each contribution period.
$
%
years
$Optional. Added at the end of each contribution period.
Compounding and contribution timing

Both default to monthly, which is what most accounts do.

Estimated ending balance

$16,288.95$6,288.95 of growth
Starting amount$10,000.00What you start with
Total contributions$0.00Deposits added along the way
Growth$6,288.95Ending minus starting minus deposits
How we got this
  1. Starting amount$10,000.00
  2. Total contributionsNo recurring contributions$0.00
  3. Ending balance5% compounded annually for 10 years$16,288.95
What we assumed
  • Contributions are added at the end of each contribution period, after interest for that compounding step is applied when the dates line up.
  • The rate is a nominal annual interest rate, not a bank APY quote and not APR.
  • This does not include taxes, fees, or inflation.
  • This is a savings-growth estimate, not investment advice.
Technical details

Method compound-interest-v1.0.0Data Manual inputs / fixed rules

Guide

How compound interest is projected here

CostAnswer editorialIndependent calculator publisher

A starting balance and optional recurring deposits grow at the rate and compounding frequency you type. Contributions are added at the end of each period. The result is a projection from those assumptions, not a forecast of a bank or market.

Compounding frequency

Annual, monthly, and daily compounding change how often interest is credited. The same stated rate produces slightly different balances. Recurring deposits are applied at period ends, so a deposit does not earn a full period of interest on the day it is added.

Questions about this calculator

Does this use APY or APR?

It uses the rate and compounding frequency you enter. If you have an APY from a bank, that APY already includes compounding; do not also pick a faster compounding frequency unless you know the bank’s nominal rate.

Are deposits at the beginning or end of the period?

End of period. That is slightly more conservative than beginning-of-period deposits.

Terms used here

Compounding
Interest credited on a balance that already includes past interest.
APY
Annual percentage yield, which already reflects compounding. Not the same as a nominal APR.

Practical tips

  • For a CD with a published APY, the CD calculator is the more honest fit.
  • Inflation is not subtracted here; use the inflation calculator if you want buying power.

Limits and caveats

  • Projection, not a guaranteed return. Markets and banks do not pay a smooth rate.

Results are for information. They are not legal, tax, medical, or financial advice. How the math is maintained · Report a wrong figure.

Engine notes

Rounding, versioning, and omissions that sit beside the guide rather than repeating it.

  • Compounding. Interest is added at the compounding frequency you choose. More frequent compounding grows a little faster at the same nominal rate.
  • Contributions. Recurring deposits are added at the end of each contribution period, after interest for a matching compounding step. That assumption is visible under What we assumed.
  • What is left out. Taxes, account fees, and inflation are not included. A 0% rate just adds your deposits to the starting amount.

Calculation receipt

What each number here is

This answer is arithmetic on what you enter. No outside dataset is involved, so nothing here can go out of date.

Compounding is defined by principal, rate, frequency and time.

Sources

Where this data comes from

Investor.govThe SEC’s compound interest explainer and calculator notes.Official guidance ↗

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