Savings Interest Calculator
What your savings account earns each month and over any period, from its APY.
Good to know. APY already counts the compounding. That makes it the one number to compare between accounts.
Not financial advice. Uses only the numbers and rates you enter — no live data.
How it works
In plain words
APY is the yield over a full year with compounding included. Over any period, raise one plus the APY to the number of years (months ÷ 12) and multiply by the balance.
The formula
balance at the end = balance × (1 + APY)^(months ÷ 12) interest = balance at the end − balance
Worked example
10,000 at 4% APY earns 400.00 in a year. The first month brings 10,000 × (1.04^(1/12) − 1) = 32.74, a little less than a twelfth, because the interest itself earns interest as the year goes on.
Sources
- Truth in Savings Act, Regulation DD (12 CFR 1030) Banks must quote APY, the yearly yield with compounding included, so accounts can be compared.
- Brealey, Myers and Allen, Principles of Corporate Finance, chapter 2 The standard formulas for loan payments, compounding and present value, the same as a spreadsheet’s PMT and FV.
Sources checked October 3, 2026. 4 automated tests check its answers on every change.
About the savings interest calculator
Savings accounts quote an APY, the annual percentage yield. Unlike a loan’s APR, it already includes compounding: it is exactly what a balance earns over a year if you leave it alone. That makes it the right number to compare accounts with, whether they pay interest daily or monthly.
Over a period shorter or longer than a year, the yield grows the same way: the balance is multiplied by one plus the APY for every year, including parts of a year. So 10,000 at 4% earns 400 in a year, about 198 in six months and about 2,167 in five years.
Rates on savings accounts can change at any time, so treat a long-period result as a guide: it assumes today’s APY for the whole period. A certificate of deposit locks the rate in, at the cost of access to your money.
Interest on savings is usually taxable income in the year it is paid, and inflation reduces what it buys. To plan regular deposits towards a target, use the savings goal calculator; for deposits growing over many years, the compound interest calculator.
Questions people ask
How much interest will 10,000 earn in a savings account?
At 4% APY, 400 in a year, or about 32.74 in the first month. At 5% APY, 500 in a year.
What is the difference between APY and APR?
APY includes compounding, so it is the true yearly yield. APR is the rate before compounding. For savings, compare APYs.
Is savings interest paid monthly?
Most accounts work interest out daily and pay it monthly. The APY already accounts for that, so the yearly result is the same.