Retirement Savings Duration CalculatorFree · No signup
$
$
%
%
How Long Will My Retirement Savings Last: The Formula
The calculator uses the annuity depletion formula to find how many months a lump sum will last at a fixed monthly withdrawal and constant investment return. If the monthly return on your balance exceeds your withdrawal, the portfolio never depletes. Pair this with the 401k Calculator with Match to see how much you will have saved by retirement before running this calculation.
n = -ln(1 - P x r / W) / ln(1 + r)
P = starting balance
r = monthly return = annual return / 12
W = monthly withdrawal
If W ≤ P x r: portfolio lasts indefinitely
How Long Will My Retirement Savings Last Calculator: Withdrawal Rate Guide
The table below shows how long different savings balances will last at various monthly withdrawal amounts, assuming a 5% average annual return. Use this as a quick reference before running the calculator with your specific numbers. If you are in the early accumulation phase, the Coast FIRE Calculator shows how much you need saved today so compound growth covers retirement without further contributions.
Savings Balance
$2,000/mo
$3,000/mo
$4,000/mo
$5,000/mo
$250,000
15 years
9 years
6 years
5 years
$500,000
Forever
24 years
15 years
11 years
$750,000
Forever
Forever
31 years
20 years
$1,000,000
Forever
Forever
Forever
36 years
Assumes 5% average annual return, no inflation adjustment. Enter your own numbers above for a precise result.
How Long Will My Retirement Savings Last with Inflation
Inflation reduces how long savings last by lowering the real return on your portfolio. The calculator uses the real return formula to adjust for inflation: Real Return = (1 + Nominal Rate) / (1 + Inflation Rate) - 1. A 7% nominal return with 3% inflation gives a real return of about 3.9%, not 4%. The table below shows how the same portfolio scenario changes across inflation assumptions. Tax-advantaged accounts like a Roth IRA grow tax-free, which helps offset inflation over time. See the Roth IRA Contribution Calculator to check how much you can contribute annually.
Inflation Rate
Real Return
Duration ($500k, $3,000/mo, 7% nominal)
0%
7.0%
51 years
1%
5.9%
29 years
2%
4.9%
23 years
3%
3.9%
20 years
4%
2.9%
18 years
How Long Will My Retirement Savings Last with Social Security
Social Security income reduces how much you need to withdraw from personal savings each month, which significantly extends portfolio longevity. To use this calculator correctly, enter only the gap between your total monthly spending and your fixed income sources (Social Security, pension, rental income). Do not enter your total living expenses.
Total monthly spending: $5,000
Social Security income: $2,200
Required from savings: $2,800/mo (enter this)
$500k at 5% return, $2,800/mo: 33 years
$500k at 5% return, $4,000/mo: 15 years (without Social Security)
Social Security adds 18 years of runway on a $500k portfolio.
Delaying Social Security from age 62 to 70 increases your monthly benefit by approximately 77%. This reduces the required monthly withdrawal from savings, often extending portfolio life by 10 or more years. The tradeoff is drawing down savings faster in the early retirement years before Social Security kicks in.
Example Calculation
You retire at 65 with $600,000 saved. You plan to withdraw $3,500 per month. You expect a 6% nominal portfolio return and 2.5% inflation. Check how much you should have saved before retiring with the Coast FIRE Calculator.
Balance: $600,000
Monthly withdrawal: $3,500
Nominal return: 6.0%
Inflation rate: 2.5%
Real return = (1.06 / 1.025) - 1 = 3.41%
Monthly real rate: 0.2842%
Monthly interest: $600,000 x 0.002842 = $1,705
Duration: approximately 28 years (lasts to age 93)
Common Mistakes to Avoid
Using nominal returns without adjusting for inflation
A 7% portfolio return with 3% inflation is a 3.9% real return. If your spending increases with inflation over time, use the inflation field in this calculator to get a realistic duration estimate.
Not accounting for taxes on withdrawals
Traditional 401k and IRA withdrawals are taxable income. In the 22% bracket, you need to withdraw about $3,846 gross to net $3,000 after tax. Enter the gross withdrawal figure, not your spending target.
Assuming returns are constant each year
Real portfolios experience sequence-of-returns risk. A major loss in the first few years of retirement (when the balance is highest) has far greater impact on longevity than the same loss later. This calculator assumes a steady return, not market volatility.
Entering total expenses instead of net savings withdrawal
If you receive Social Security, pension, or rental income, enter only the gap between your total spending and that income as the monthly withdrawal. Entering total expenses will underestimate how long savings last.
Ignoring large irregular expenses
Healthcare, home repairs, and travel cause irregular large withdrawals not captured in a fixed monthly figure. Add 10-15% to your assumed monthly withdrawal to account for these lumpy expenses.
Frequently Asked Questions
At $3,000 per month withdrawal with 5% annual return, $500,000 lasts approximately 24 years. At $2,083 per month (the breakeven point where withdrawals equal monthly interest), the portfolio lasts indefinitely. At $4,000 per month, about 15 years. At $5,000 per month, approximately 11 years. Reducing monthly withdrawal by $500 typically adds 3-5 years to the portfolio lifespan.
Research on sustainable withdrawal rates, Social Security claiming strategies, sequence-of-returns risk, and retirement income sufficiency across different scenarios.
Reference for RMD rules affecting traditional 401k and IRA withdrawals, including the age requirements and tax treatment of retirement account distributions.
HR
Hassaan Rasheed
Developer and Researcher, CalculatorFlux
Researches and verifies the formulas, methodology, and source data behind each calculator on CalculatorFlux. All tools are built and checked against the cited references before publication.
Last updated: May 2026
Duration by Withdrawal Rate
Annual Rate
Duration
3% (very safe)
40+ years
3.5% (safe)
35+ years
4% (4% rule)
30 years
5% (moderate)
22 years
6% (aggressive)
17 years
8% (high risk)
12 years
Assumes 7% avg annual return. Actual results vary.
Pro Tip
Reducing your monthly withdrawal by $200 on a $500,000 portfolio can add 3-5 years to its lifespan. Small spending adjustments in early retirement have an outsized effect because your balance is at its highest point.