Estimate how long your savings will last or the monthly withdrawal you can take with an asset depletion calculator and annual return.
Customize This Calculator
Build your own version. Describe what you want changed, added, or compared.
Asset Depletion Formula
The asset depletion calculator uses one of two formulas, depending on whether you want to find how long your savings will last or how much you can withdraw each month.
How long will savings last?
If there is no investment return, the calculation is simple depletion:
If the remaining balance earns a monthly return, the calculator uses:
- n = number of months your savings will last
- P = starting savings or assets
- W = monthly withdrawal
- r = monthly return, calculated as annual return ÷ 12
Monthly withdrawal amount
If there is no investment return, the calculator divides your assets by the number of months:
If the remaining balance earns a monthly return, the calculator uses the payment formula:
- W = monthly withdrawal amount
- P = starting savings or assets
- r = monthly return, calculated as annual return ÷ 12
- n = total number of months, calculated as years × 12
The “How long will it last?” function estimates the number of months before the balance reaches zero. If the monthly growth is greater than or equal to the withdrawal, the calculator reports that the balance does not run out under those assumptions.
The “Monthly withdrawal” function estimates the fixed monthly amount that would deplete the starting balance over your chosen number of years, while applying the selected return to the remaining balance.
Withdrawal Rates and Return Assumptions
Use these tables to interpret the result. They are general planning references, not guarantees.
| Annual withdrawal rate | Monthly withdrawal on $500,000 | Common interpretation |
|---|---|---|
| 3% | $1,250 | More conservative, often used for longer horizons |
| 4% | $1,667 | Traditional retirement planning guideline |
| 5% | $2,083 | Higher withdrawal, more sensitive to market returns |
| 6% | $2,500 | Aggressive for a long retirement unless returns are strong |
| Annual return setting | Typical use | Planning note |
|---|---|---|
| 0% | No-growth cash estimate | Shows pure depletion with no interest or investment gain |
| 2% | Cash or conservative savings | May be closer to short-term savings assumptions |
| 4% | Conservative portfolio estimate | Often used for cautious long-term projections |
| 6% to 8% | Balanced to stock-heavy portfolio | Higher expected return also usually means higher volatility |
Example Asset Depletion Calculations
Example 1: How long $500,000 lasts with $3,500 monthly withdrawals
Assume you have $500,000 in savings, withdraw $3,500 per month, and select a 4% annual return.
The result is about 194 months, or about 16 years and 2 months.
Example 2: Monthly withdrawal from $500,000 over 25 years
Assume you want $500,000 to last 25 years and select a 4% annual return.
The result is about $2,639 per month, or about $31,670 per year.
Asset Depletion Calculator FAQ
What does asset depletion mean?
Asset depletion means using savings or investment assets to support spending over time. In this calculator, your assets are reduced by a fixed monthly withdrawal and, if selected, increased by an assumed return on the remaining balance.
Does the calculator include taxes, inflation, or fees?
No. The calculation uses the starting savings amount, withdrawal amount or time period, and the selected annual return. It does not adjust for income taxes, investment fees, inflation, required minimum distributions, or changes in spending. If those items apply, your real-world result may be lower than the estimate shown.
Why can the result say my money lasts forever?
If the selected return produces monthly growth that is greater than or equal to the monthly withdrawal, the formula does not reach a zero balance. For example, $500,000 at a 4% annual return has estimated first-month growth of about $1,667. If you withdraw less than that, the balance grows under the calculator’s fixed-return assumption.
