Money, First Principles
Calculator

How much could my savings grow?

Compound interest means you earn interest on your interest. Enter a few numbers to see how small, steady deposits can add up.

What you have saved today. Can be $0.

How much you'll add each month.

Show rates as

"As quoted" shows each rate the way lenders and banks quote it. Results don't change.

The 7% APR to start is an illustration, not a promise. Real rates depend on where the money is and change over time.

7.00% APR (7.23% APY), compounded monthly

APR vs. APY: why the same rate has two numbers

APR (annual percentage rate) is the yearly rate before compounding.APY (annual percentage yield) is what you actually pay or earn in a year once interest starts charging, or earning, interest of its own.

Lenders quote APR because it's the smaller number. Banks quote savings in APY because it's the bigger one. A 9.00% APR car loan charged monthly costs 9.38% a year. A 24.00% APR card charged daily costs 27.11%. A 5.00% APY savings account is a 4.89% APR.

To compare any two rates fairly, put them in the same unit. "Show rates as" switches every rate on the page; the results don't change, because the rate underneath doesn't.

Kind of rateQuoted asHow it's applied
Car, mortgage and personal loansAPRAPR ÷ 12, each month
Credit cardsAPRAPR ÷ 365, each day, compounded
SavingsAPYMonthly, from the APY
Investment returnsYearly (APY basis)Monthly: (1 + rate)1/12 − 1

A loan's APR can include some fees as well as interest, so turning it into an APY here covers interest only. Inflation is always a plain yearly rate.

Balance after 30 years

$0

You put in
$0
Interest earned
$0
Your balance, year by year

What this means

Time does most of the work. Starting earlier, even with a smaller amount, usually beats starting later with more, because your interest has longer to earn interest of its own.

Educational estimate only. Real returns change from year to year and aren't guaranteed, and this doesn't account for taxes, fees or inflation.

See the year-by-year table
YearYou put inInterest earnedBalance