How does the calculator decide when the money runs out?

It runs a month-by-month simulation. Each month the remaining balance earns that month’s growth, then the withdrawal is taken out. The loop stops when the balance reaches zero or below, or when the 100-year model cap is reached.

What does the annual withdrawal increase do?

It increases the monthly withdrawal once every 12 months. A 2% step-up means month 13 onward uses 102% of the starting withdrawal, month 25 onward uses 104.04%, and so on.

Why does the calculator show month and year instead of an exact date?

This is a planning tool for runway questions, not a day-precision cash ledger. The model anchors the answer to a start month and year because “around March 2031” is usually the useful decision point.

What if the balance does not run out within the modeled horizon?

The calculator says so directly instead of inventing a depletion date. In that case, the assumptions you entered keep the balance above zero throughout the 100-year cap.

How should I use the optional target duration?

Use it as a checkpoint. You still get the full depletion answer, but the target horizon also tells you whether the plan survives to that point and, if not, how large the shortfall is by then.

Savings Withdrawal Calculator

Estimate how long your savings last when you start drawing from them every month. Set a starting balance, monthly withdrawal, expected return, optional annual step-up, start month, and an optional target horizon.

Currency

Drawdown setup

Starting savings balance

Monthly withdrawal

Expected annual return

Calendar and step-up

Annual withdrawal increase

Start month

Start year

Optional target horizon

Target duration

Target duration unit

Examples

Enter values above to see results

How It Works

Formula

B_t = B_{t-1} \times \left(1 + \frac{r}{12}\right) - W_t

W_t = W_0 \times (1 + g)^{\left\lfloor \frac{t-1}{12} \right\rfloor}

Enter your savings balance, monthly withdrawal, expected annual return, optional annual withdrawal increase, and a start month and year. The calculator then projects the balance forward one month at a time so the result stays honest in flat-return, negative-return, and rising-withdrawal scenarios.

Month-by-month drawdown method:

Start with the current balance.
Apply one month of growth: $B_{t-1} \times (1 + r/12)$ .
Subtract that month’s planned withdrawal.
If you entered an annual withdrawal increase, raise the monthly withdrawal once every 12 months.
Repeat until the balance reaches zero or the model reaches 100 years.