A how long will my money last calculator retirement is one of the most important tools you can use before you stop working. According to the U.S.
Federal Reserve's 2022 Survey of Consumer Finances, the median retirement account balance for Americans aged 55–64 was approximately $185,000 — a figure that many financial planners consider insufficient for a 20- to 30-year retirement.
The problem is simple: most people guess at their retirement readiness instead of calculating it. They assume Social Security will cover the gap or that their spending will naturally decline. In reality, retirement often brings higher healthcare costs, surprise home repairs, and decades of inflation.
This article breaks down exactly how a retirement money duration calculator works, which inputs matter most, and how to use the results to make confident decisions. You will learn the five key steps, the best free tools available, and the mistakes that cause people to outlive their savings.
What a Retirement Money Duration Calculator Actually Does
A how long will my money last calculator retirement estimates the number of years your savings can sustain your withdrawals. It runs a simulation using your starting balance, annual spending, expected investment returns, and inflation rate.
The output typically shows a "depletion age" — the year your portfolio hits zero. Some calculators also display a probability score, such as "92% chance your money lasts 30 years."
The math behind these tools comes from the Monte Carlo simulation method, which runs thousands of possible market scenarios. Instead of assuming one fixed return, Monte Carlo accounts for bad years, good years, and everything in between. This gives you a range of outcomes rather than a single misleading number.
Vanguard's retirement income calculator and Fidelity's retirement score tool both use this approach. The key insight: a 6% average return does not mean you can safely withdraw 6% every year. Sequence-of-returns risk — earning poor returns in your early retirement years — can devastate a portfolio even when long-term averages look fine.
How to apply this: Run at least three different calculators and compare the depletion ages. If they cluster within a few years of each other, you have a reliable estimate.
Step 1: Gather Your Real Numbers
The accuracy of any how long will my money last calculator retirement depends entirely on the inputs you feed it. Garbage in, garbage out applies here more than almost anywhere in personal finance.
Start with your retirement account balances: 401(k)s, IRAs, brokerage accounts, pensions, and any cash you plan to draw from. Next, list your guaranteed income sources: Social Security, pensions, annuities, or rental income.
The most difficult number is your annual spending. Many people underestimate this by 20–30% because they forget irregular expenses. A roof replacement, a new car, or a dental implant can add thousands to a single year's budget.
According to the U.S. Bureau of Labor Statistics' 2022 Consumer Expenditure Survey, households led by someone 65 or older spent an average of roughly $57,800 per year. That figure includes housing, healthcare, food, and transportation. Your number may differ, but it gives you a benchmark.
How to apply this: Pull your last 12 months of bank and credit card statements. Total every outflow, divide by 12, and use that as your monthly spending baseline.
Step 2: Choose a Reliable Calculator
Not all retirement calculators are equal. Some are marketing tools designed to funnel you toward a financial advisor. Others are built by reputable institutions with transparent methodologies. Here are three trustworthy options:
| Calculator | Best For | What to Check | Action to Take |
|---|---|---|---|
| Fidelity Retirement Score | Quick snapshot | Your score out of 150 | Adjust savings rate until score improves |
| Vanguard Retirement Income Calculator | Income sustainability | Probability of success | Aim for 85%+ probability |
| FIRECalc | Historical backtesting | Worst-case scenario | Test against 1966 retirement year |
FIRECalc is particularly useful because it tests your plan against every historical market period since 1871. If your portfolio survived the 1966 retiree who faced high inflation and poor stock returns, your plan is likely robust.
A common scenario: someone enters $500,000 in savings, $40,000 in annual spending, and a 30-year horizon. With a 60/40 stock-bond portfolio, FIRECalc might show an 82% success rate. That means 18% of historical scenarios would have depleted the portfolio early.
How to apply this: Run your numbers through FIRECalc first because it is free and historically grounded. Then cross-check with Fidelity or Vanguard for a second opinion.
Step 3: Understand the 4% Rule and Its Limits
The 4% rule is the most cited guideline in retirement planning. It states that you can withdraw 4% of your portfolio in year one, then adjust that dollar amount for inflation each year, and have a high probability of not running out over 30 years.
William Bengen, a financial advisor, first published this research in 1994. His analysis of historical market data showed that a 4% initial withdrawal rate survived every 30-year retirement period he tested.
However, Bengen himself has since revised his thinking. In a 2020 interview with the Financial Planning Association Journal, he noted that current low bond yields and high stock valuations may require a lower initial rate — closer to 3.5% for conservative retirees.
A how long will my money last calculator retirement lets you test different withdrawal rates instantly. Drop from 4% to 3.5% and watch how many additional years your money lasts. The results are often striking: a half-percent change can add 5–8 years of portfolio life.
How to apply this: Run your calculator with a 3.5% withdrawal rate, then 4%, then 4.5%. Note the depletion age for each. This gives you a practical range to plan around.
Step 4: Account for Inflation and Healthcare Costs
Inflation is the silent killer of retirement portfolios. A 3% annual inflation rate cuts your purchasing power in half over roughly 24 years. A how long will my money last calculator retirement that ignores inflation produces dangerously optimistic results.
Healthcare deserves special attention. Fidelity's 2023 Retiree Health Care Cost Estimate reports that a 65-year-old couple retiring that year would need approximately $315,000 saved after taxes just for medical expenses throughout retirement. That figure excludes long-term care, which can cost $100,000 or more per year.
Medicare does not cover everything. Dental care, hearing aids, eyeglasses, and most long-term care are excluded. Many retirees face surprise out-of-pocket costs in these categories.
Consider a retiree who budgets $60,000 per year for living expenses but forgets healthcare. If medical costs add $10,000 annually, their portfolio depletes years earlier than the calculator predicted. The error compounds because that $10,000 also grows with inflation.
How to apply this: Add a separate healthcare line item to your retirement budget. Use $7,000–$10,000 per person per year as a starting estimate, and increase it by 5–6% annually in your projections.
Step 5: Stress-Test Your Plan and Adjust
The final step is to stop treating your how long will my money last calculator retirement result as a one-time answer. It is a living estimate that needs regular stress-testing.
Run worst-case scenarios: What if the market drops 30% in your first retirement year? What if you live to 95 instead of 85? What if Social Security benefits are reduced by 20%? Each of these scenarios is plausible, and each changes your depletion age.
The Social Security Administration's 2024 Trustees Report projects that the trust fund reserves will be depleted by 2035 if no legislative changes occur. At that point, ongoing tax revenue would cover roughly 83% of scheduled benefits. Planning for a reduced benefit is prudent, not paranoid.
Adjustment levers include working one or two extra years, reducing spending, relocating to a lower-cost area, or shifting to a more conservative withdrawal rate. Even small changes compound dramatically over a 30-year horizon.
How to apply this: Re-run your calculator every year, or after any major life event. Treat the output as a dashboard gauge, not a fixed destination.
Frequently Asked Questions About how long will my money last calculator retirement
What is the biggest mistake people make with retirement calculators?
The biggest mistake is underestimating lifespan. Many people plan for a 20-year retirement when they actually live 30 years or more. A how long will my money last calculator retirement only works if you enter a realistic horizon. One spouse in a married couple has a significant chance of living past 90, so plan for the longer-lived partner's needs.
Can I rely on Social Security to cover most of my expenses?
No. Social Security replaces roughly 40% of pre-retirement income for an average earner, according to the Social Security Administration. A how long will my money last calculator retirement should treat Social Security as a supplement, not a foundation. Most planners recommend covering at least 60% of your spending from personal savings and guaranteed income sources.
Should I include my home equity in the calculator?
Generally no, unless you have a concrete plan to access it. Home equity only helps if you sell, downsize, or take a reverse mortgage. A how long will my money last calculator retirement works best when you only include liquid, investable assets.
If you plan to downsize, add the expected net proceeds as a one-time future deposit rather than current spending power.
What withdrawal rate should I use if I retire early?
Early retirement requires a lower rate. Someone retiring at 55 has a 40-year horizon, not 30. A how long will my money last calculator retirement run with a 4% rate over 40 years shows meaningfully lower success probabilities. Many early retirees target 3–3.5% initial withdrawals and maintain flexible spending that can drop during market downturns.
How often should I recalculate my retirement plan?
At minimum, annually. Also recalculate after any major event: a market crash, a health diagnosis, an inheritance, or a relocation. A how long will my money last calculator retirement reflects a snapshot in time. Regular updates catch slow drift before it becomes a crisis.
If your depletion age moves earlier two years in a row, that is a signal to adjust spending or income.
Conclusion
Planning for retirement without a calculator is like navigating without a map. A how long will my money last calculator retirement gives you the data you need to make confident decisions.
Key takeaways from this guide:
- Your inputs matter more than the tool you choose — accurate spending data is essential
- Test multiple calculators, including FIRECalc, Fidelity, and Vanguard, and compare results
- The 4% rule is a starting point, not a guarantee — stress-test lower withdrawal rates
- Healthcare and inflation deserve their own line items in every projection
- Recalculate annually and after major life events to catch problems early
Your next step is simple: gather your account balances and spending data today, then run your numbers through at least two of the calculators mentioned above. The 20 minutes you spend now could add years of financial security to your retirement.
