High-Yield Savings Calculator: How Much Interest Could You Earn?
Estimate savings growth from a starting balance, APY, monthly deposits, and time.
Calculate your scenario
How to calculate interest on a high-yield savings account
Enter your starting balance, savings account APY, monthly deposits and time horizon. The calculator estimates how much interest could be earned and shows your ending balance separately from the money you deposited.
Because APY already reflects annual compounding, this calculator converts the APY to an equivalent monthly rate rather than simply dividing the APY by 12.
How the calculation works
APY is an effective annual yield, so the equivalent monthly rate is (1 + APY)^(1/12) − 1. The balance earns one month of interest before each end-of-month deposit. Banks may credit daily or monthly, and APY can change; this fixed-APY model does not use live bank rates.
Worked example
With a hypothetical fixed 4% APY, a $1,000 starting balance and $100 deposited at each month-end for 12 months, the estimated ending balance is $2,261.84: $2,200 in deposits and $61.84 in interest. APY can change, and actual bank interest crediting may differ.
How to read your results
Ending balance combines your starting balance, monthly contributions and estimated interest. Total deposits includes the starting balance plus contributions; interest earned is the difference between ending balance and deposits. Change an input and calculate again to compare savings scenarios.
Frequently asked question
Does a 4% APY mean 4% divided by 12 each month?
No. Dividing by 12 treats the quoted rate like a nominal APR. An APY is already effective over a year, so its equivalent monthly rate comes from taking the twelfth root.
Related calculators
Inflation Calculator Credit Card Payoff Calculator · Explore Saving & Debt Decisions
Sources and limits
CFPB Regulation DD APY calculation. Reviewed September 19, 2026. Financial rules and rates can change; verify current terms with the source or your provider.