Periodic Deposit Savings Calculator This calculator will help you to determine the after-tax future value of a periodic investment in today's dollars. Enter the initial investment (optional): Enter the Monthly Weekly Quarterly Annual deposit amount: Enter the annual interest rate (%): Enter the number of years: Enter your combined state and federal tax rate (%): Enter the expected average annual inflation rate (%): Gross future value: After-tax future value: After-tax future value accounting for inflation: