Savings Account Calculator
See how a savings balance grows with monthly deposits at a given APY, how much of it is interest, what taxes take, and how long a savings goal takes to reach.
Enter what you have, what you add each month, and your account's APY. The calculator compounds monthly, splits the result into your deposits and the interest the bank paid, and shows the year-by-year path. Add a goal and it tells you the month you reach it.
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Quick answers
Common cases, computed by this calculator with the assumptions listed under the method. Select one to load it above.
- How much is $100 a month at 4% APY after 5 years?
- $6,617.90 Balance after 5 years Open in the calculator
- What does $10,000 earn at 4.5% APY over 3 years?
- $1,411.66 ($1,101.10 after 22% tax) Interest earned Open in the calculator
- How much is $500 a month at 4% APY after 10 years?
- $73,347.96 Balance after 10 years Open in the calculator
How the math works
APY already includes compounding. We use a monthly equivalent, (1 + APY/100)^(1/12) − 1, and add deposits at month end. This is a simplified constant-rate model; actual accounts can accrue interest daily and rates can change. Displayed amounts are rounded to cents; the model does not round each monthly interest credit.
Worked example
$10,000 with no deposits at 4% APY earns $400 in one year. At zero interest, a $2,500 starting balance plus $250 monthly for five years becomes $17,500. A goal already covered by the starting balance is reached immediately.
Tax estimate
The after-tax interest figure subtracts the percentage you enter from total modeled interest. The account balance itself is before tax; the simulation does not withdraw annual tax payments.
Source
Calculation notes updated .