Estimate future savings balance using daily compounding APY, optional monthly deposits, and total interest earned.
Overview
High-yield online savings accounts are often compared by APY, but the balance you actually reach depends on starting deposits, recurring contributions, and how interest compounds. This calculator models daily compounding on a savings balance plus optional monthly deposits at the APY you enter.
Use it to stress-test rate changes: a 0.50 point APY shift over five years can equal hundreds or thousands of dollars depending on balance and contribution habits. Treat published APY as variable—banks change rates with market conditions.
Not affiliated with CIT Bank/Merrill. Always confirm current rates, minimum balances, and account rules on official disclosures before opening or moving funds.
Steps
Input current or planned opening deposit.
Use the annual percentage yield quoted for the account tier.
Optional recurring contribution each month.
Select years or months for the projection window.
Calculate ending balance and total interest.
Adjust APY or deposits to test sensitivity.
Math
FV with daily compounding: balance grows by (1 + APY/365)^days; deposits add at interval
Daily compounding applies APY/365 each day to the running balance. Monthly deposits increase principal before subsequent interest accrual.
Worked cases
Daily compounding on $10,000 with no deposits
Ending balance about $11,420 plus interest detail.
Deposits plus daily interest over 5 years
Contributions dominate long-run growth.
Re-run projection at lower APY
Lower ending balance highlights rate risk.
Why use this
Questions