Calculator Panel
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Enter your values above and click Calculate.
What This Calculator Does
This calculator projects the depletion timeline of your cash or investment balance as you make consistent, recurring withdrawals, showing how compounding interest extends portfolio lifespan.
How to Use This Calculator
Enter your starting savings balance, expected annual interest rate, and target recurring monthly withdrawal amount. Click Calculate to see how many years and months your funds will last.
How the Calculation Works
The underlying math engine processes your inputs using exact formulas. This systematic approach ensures professional, institutional-grade calculation precision:
Mathematical Formula
Formula Legend:
- · Interest is credited on the remaining balance at the end of each period.
- · Withdrawals are deducted at the beginning or end of each period (assumed end of month here).
Practical Example
An investor has a savings balance of $100,000 earning a 5.0% annual interest rate. They plan to withdraw $800 each month:
Step-by-Step Mathematical Walkthrough:
- 1 Initial Balance = $100,000.
- 2 Annual Return = 5.0% (0.4167% monthly).
- 3 Monthly Withdrawal = $800.
- 4 The savings will last approximately 181 months (15.1 years) before depleting to zero, generating a total of $44,791.54 in interest during the payout phase.
Important Assumptions & Notes
- The annual interest rate remains completely fixed over the depletion cycle.
- Monthly withdrawals are constant and do not adjust for inflation.
- The account balance is not replenished with any new deposits.
Common Mistakes or Considerations
- Underestimating inflation, which requires you to increase your nominal withdrawal amount over time to maintain purchasing power.
- Assuming a volatile investment portfolio will have a steady rate of return, ignoring sequence of returns risk.
Frequently Asked Questions
How can I make my savings last forever?
To make your savings last indefinitely, your monthly withdrawal must be equal to or less than the monthly interest earned (the principal remains untouched).
What is sequence of returns risk?
This is the risk that market downturns occur early in your withdrawal phase, which forces you to sell assets at low values and severely reduces portfolio longevity.
Should I hold my withdrawal reserves in a high-yield account?
Yes, holding retirement reserves in a high-yield savings account or money market account guarantees return and prolongs your capital reserves.