The bank may calculate the interest on your savings account based on the daily balance or according to tiers, limits, and a minimum, and then pay it out monthly, quarterly, or at other intervals depending on the product.
Steps
To know your actual return, read the tier table and the calculation method, not just the interest rate.
If your balance changes throughout the month, ask the bank exactly what amount is being credited to the account.
The figures, fees and limits in this answer vary by bank and change over time — confirm them with your bank or the official source before acting.