Savings Withdrawal Calculator

Savings eventually turn into spending. This calculator models that drawdown. It can estimate how long a balance lasts with a fixed monthly withdrawal, solve for the monthly withdrawal that a balance can support over a chosen period, or project the remaining balance after a set withdrawal schedule. The result is useful for bridge income, a planned sabbatical, an emergency fund drawdown, a cash reserve, or a simplified retirement spending scenario.

This page is deliberately the opposite of the accumulation tools. The savings calculator adds deposits and interest to build a balance. The savings goal calculator solves for deposits needed to hit a target. The savings withdrawal calculator starts with money already saved and tests how withdrawals interact with interest over time. For annuity math in a more formal format, compare the present value annuity calculator.

Modes and inputs

The first input, I’d like to know, selects the mode. How long will my money last? uses savings balance, annual interest rate, and monthly withdrawal. How much can I withdraw? uses savings balance, annual interest rate, withdrawal length, and desired remaining balance. How much will remain? uses savings balance, annual interest rate, monthly withdrawal, and withdrawal length.

Savings balance is the starting amount. Annual interest rate is a nonnegative percentage that the calculation divides by 100 and by 12. Monthly withdrawal is assumed to occur at the end of each month. Withdrawal length is entered in years and converted to months by multiplying by 12. Desired remaining balance is the amount you want left at the end in withdrawal mode.

Formula used for remaining balance

The remaining-balance mode compounds the starting balance and subtracts the future value of withdrawals:

$\text{remaining balance} = \text{starting balance} \times (1 + \text{monthly rate})^{\text{months}} - \text{monthly withdrawal} \times \frac{(1 + \text{monthly rate})^{\text{months}} - 1}{\text{monthly rate}}$

When the monthly rate is zero, the calculatorula becomes starting balance minus monthly withdrawal times months:

$\text{remaining balance} = \text{starting balance} - \text{monthly withdrawal} \times \text{months}$

The calculator floors the displayed remaining balance at $0 in remaining mode, so a depleted account does not show as a negative cash balance.

Formula used for monthly withdrawal

In withdrawal mode, the calculator solves for the level monthly payment that leaves the desired ending balance:

$\text{monthly withdrawal} = \frac{(\text{starting balance} \times (1 + \text{monthly rate})^{\text{months}} - \text{remaining goal}) \times \text{monthly rate}}{(1 + \text{monthly rate})^{\text{months}} - 1}$

When the rate is zero, it uses starting balance minus remaining goal, divided by months. If the calculated payment is below zero because the remaining goal is too high, the displayed withdrawal is floored at $0.

Formula used for duration

Duration mode solves the annuity depletion equation for months:

$\text{months} = \frac{-\log(1 - \frac{\text{monthly rate} \times \text{starting balance}}{\text{monthly withdrawal}})}{\log(1 + \text{monthly rate})}$

If the rate is zero, duration is starting balance divided by monthly withdrawal. If the monthly withdrawal is zero, or if monthly interest is enough to cover the withdrawal, the calculator reports an indefinite duration under the constant-rate assumption.

Checking the result

The default duration scenario uses a $100,000 savings balance, a 2% annual interest rate, and a $500 monthly withdrawal. The monthly rate is 0.02 ÷ 12, or about 0.00166667. The monthly interest at the start is about $166.67, which is less than the $500 withdrawal, so the account is not indefinite.

Using the duration formula, the balance lasts about 243.48 months. The display rounds up to whole withdrawal periods, so it reports 20 years 4 months and 244 withdrawals. Total withdrawn is based on the unrounded duration in the calculation: $500 × 243.4817 = $121,740.87. Interest earned during withdrawals is total withdrawn minus the starting $100,000, or $21,740.87.

In the same inputs but remaining-balance mode over exactly 20 years, the projected ending balance is about $1,734.39. In monthly-withdrawal mode over 20 years with a desired remaining balance of $0, the supported monthly withdrawal is about $505.88.

Using the estimate responsibly

The estimate is strongest for stable cash accounts and short bridge periods. It is weaker for volatile investments because real returns do not arrive as a smooth monthly rate. Inflation also matters: a flat $500 withdrawal buys less over time. Taxes, transfer limits, early withdrawal penalties, fees, and account rules can all change spendable cash.

For a retirement context, compare with the retirement calculator and future value annuity calculator. For short-term reserves, rebuild the balance with the emergency fund calculator after the drawdown ends.

Informational note

This calculator is an educational arithmetic tool. It does not recommend a withdrawal rate, choose investments, or evaluate whether a plan is safe. Use conservative rates for essential spending, keep a reserve for surprises, and revisit the plan when rates, expenses, or account balances change.

Sources

• CFPB, Before you claim Social Security — retirement timing and income planning context.
• Investor.gov, Compound Interest — compounding definition relevant to drawdown calculations.
• FDIC, Saving for the Unexpected and Your Future — emergency savings context for cash reserves.