A how long will my money last retirement calculator estimates the year your savings will run dry based on your balance, spending, and investment returns. It answers one question most retirees avoid: will my nest egg outlive me?
The stakes are real — the Society of Actuaries reports that a healthy 65-year-old couple has a meaningful chance of at least one spouse living past 90, meaning a retirement could stretch 25 to 30 years. Yet many people never run the numbers until they've already left work.
This guide walks you through how these calculators work, which inputs matter most, the rules of thumb behind them, and the mistakes that skew results. By the end, you'll be able to run an accurate projection in about 15 minutes.
What a Retirement Longevity Calculator Actually Does
A longevity calculator runs a simple but powerful projection: it starts with your savings, subtracts your annual withdrawals, adds investment growth, and keeps going until the balance hits zero. The output is a number of years — or an age at which your money runs out.
This is exactly what a how long will my money last retirement calculator is built to show you.
Most calculators also apply inflation, usually around 2-3% per year, so your future withdrawals buy less than today's dollars. Fidelity's retirement tools build this in automatically, which is why their projections often look more conservative than a back-of-the-envelope division of savings by years.
The best calculators go further and test hundreds of market scenarios at once, a method called a Monte Carlo simulation. Instead of one straight-line return like 6%, the tool tests good years, bad years, and crashes. You get a probability — say, an 85% chance your money lasts to age 95 — which reflects real market volatility.
How to apply this: Run one straight-line calculation and one Monte Carlo projection. If the results differ sharply, trust the probability-based version.
The 7 Inputs That Control Your Answer
Every projection is only as good as its inputs, and a how long will my money last retirement calculator is no exception. Get these wrong and the output is meaningless no matter which tool you use.
- Current savings balance — include 401(k)s, IRAs, taxable accounts, and cash
- Annual spending in retirement — most people underestimate this
- Other income — Social Security, pensions, rental income
- Expected investment return — typically 5-7% for a balanced portfolio
- Inflation rate — usually 2-3%
- Retirement age and life expectancy — plan to 90 or 95, not your family average
- One-time costs — a mortgage payoff, a new car, healthcare gaps before Medicare
Spending is the input people get wrong most often. A common scenario: a retiree budgets $4,000 per month using today's bills, then forgets the $700 monthly health insurance premium they'll pay between leaving work at 62 and Medicare at 65. That gap alone can shorten a projection by years.
How to apply this: Pull last year's actual spending from your bank and credit card statements before you touch a how long will my money last retirement calculator — don't guess.
How the 4% Rule Anchors Every Calculator
The 4% rule comes from the 1994 "Trinity Study" research by William Bengen and later professors at Trinity University. It found that withdrawing 4% of your starting balance in year one, then adjusting for inflation each year, historically made money last at least 30 years across most market conditions.
A quick mental shortcut: divide your savings by 25 (the inverse of 4%). A $600,000 portfolio supports roughly $24,000 per year in year one, before Social Security. If a how long will my money last retirement calculator tells you your money runs out early, compare its implied withdrawal rate — anything above 5% should raise a flag.
Today many planners treat 4% as a starting point rather than a guarantee. Lower expected bond returns and longer lifespans have pushed some researchers toward 3.5% or dynamic withdrawals that flex with market performance.
As Fidelity's retirement planning guidance explains, its benchmark is to have saved about 10 times your salary by age 67 to maintain your lifestyle — a different lens on the same math.
How to apply this: Calculate your own withdrawal rate (annual need ÷ total savings). If it exceeds 4-5%, a how long will my money last retirement calculator will confirm you need to adjust.
Best Free Tools: A Side-by-Side Comparison
You don't need to pay for software. These free, reputable tools each take a slightly different approach, and any how long will my money last retirement calculator on this list beats guessing.
| Tool | Best for | Key strength | What to check |
|---|---|---|---|
| Fidelity Retirement Score | Overall readiness | Scores you 0-150 vs. your goal | Your score and the age gap it shows |
| AARP Retirement Calculator | Quick first run | Simple inputs, fast results | Whether Social Security is included |
| SSA Life Expectancy Tables | Longevity input | Actuarial data by age and sex | Your 50% and 25% survival ages |
Consider a 60-year-old with $500,000 saved, $30,000 in expected Social Security, and $55,000 in annual spending needs. Plugging those numbers into the Fidelity tool might show a shortfall at a moderate score, signaling she should delay claiming benefits or trim spending by a few thousand dollars per year. The AARP tool would confirm the ballpark in half the time.
How to apply this: Run your numbers in at least two tools. If both say your money runs out before 85, treat that as a signal to act, not an estimate to ignore.
5 Mistakes That Make Your Projection Wrong
A how long will my money last retirement calculator can't fix bad inputs. These five errors are the most common — and the most costly.
- Using average life expectancy. Planning to the average (around 85) fails half the time. The SSA tables show a substantial share of 65-year-olds live well into their 90s.
- Ignoring inflation on spending. $50,000 of expenses today needs roughly $90,000 at 3% inflation in 20 years.
- Forgetting taxes. Withdrawals from traditional 401(k)s and IRAs are taxed as income, so $60,000 of spending requires closer to $70,000 pre-tax.
- Assuming steady returns. A bad market early in retirement — sequence-of-returns risk — can drain a portfolio even when the long-term average looks fine.
- Excluding healthcare before Medicare. Pre-65 premiums and out-of-pocket costs routinely surprise early retirees.
Here's a case that shows the stakes: a couple planned to 85 because "nobody in our family lives past that." One spouse turned 92 with a depleted portfolio, forced to rely entirely on Social Security. Planning to 90 or 95 instead costs nothing in the calculator and protects the downside.
How to apply this: Rerun your projection once with spending planned to age 95 and taxes added. If the result worries you, that discomfort is useful data.
Frequently Asked Questions About how long will my money last retirement calculator
How accurate are retirement longevity calculators?
They are estimates, not promises — accuracy depends entirely on your inputs and future market returns. Tools using Monte Carlo simulation are generally more realistic than straight-line math. Use a how long will my money last retirement calculator as a direction-checker every year, not a one-time verdict, and update inputs as reality unfolds.
What withdrawal rate makes money last 30 years?
Historical research supports roughly 4% of your starting balance, adjusted for inflation, over 30 years. If you retire in a downturn or expect a very long retirement, consider 3.5% or flexible withdrawals. A how long will my money last retirement calculator can test whether your chosen rate survives early market losses.
Do these calculators include Social Security?
Most quality tools do, either automatically or as an input you provide from your SSA statement. Verify the assumed claiming age — claiming at 62 versus 70 can change monthly benefits by a large margin. When your how long will my money last retirement calculator shows a shortfall, delaying benefits is often the single highest-impact fix.
Should I use a calculator if I have a pension?
Yes — a pension changes your inputs, not the need for the math. Enter the pension as guaranteed annual income, then calculate withdrawals only for the gap it leaves. A how long will my money last retirement calculator will then show a smaller required portfolio, which may let you retire earlier than you assumed.
How often should I rerun my retirement numbers?
At least once a year, plus after any major life event — a job loss, inheritance, health change, or market crash. Markets move and spending drifts, so a three-year-old projection is nearly useless. Treat your how long will my money last retirement calculator like an annual physical: routine, quick, and honest.
Conclusion: Run the Numbers Before Time Runs Out
A how long will my money last retirement calculator turns vague anxiety into a concrete answer you can act on. The key takeaways:
- Plan to age 90 or 95, not average life expectancy
- Keep your initial withdrawal rate at or below 4%
- Include inflation, taxes, and pre-Medicare healthcare in every run
- Rerun your projection annually and after major life changes
Start today with one free tool — the Fidelity Retirement Score or the AARP calculator — and spend 15 minutes entering real numbers. Knowing your runway is the first step to extending it.
