What this calculator answers
A how long will my money last calculator helps you estimate portfolio longevity: in plain terms, how many years and months your savings can support your lifestyle. It combines five moving pieces: current balance, spending, outside income, investment return, and inflation.
Whether you're planning retirement, taking a career break, or simply testing your financial runway, this tool gives you a clear starting estimate so you can make better decisions sooner.
How the calculation works
1) Start with today’s balance
Your account balance is the fuel tank. The larger it is, the longer it can generally sustain withdrawals.
2) Subtract monthly net spending
Net spending is your monthly expenses minus any outside income (like Social Security, pension, rental income, or part-time work). If your expenses are $4,000 and outside income is $1,500, your portfolio needs to provide $2,500 per month.
3) Apply investment growth
Each month, the remaining balance grows (or shrinks) based on your expected annual return. This estimate assumes a steady return, which is useful for planning but not how real markets behave in every year.
4) Increase spending with inflation
Inflation means your future withdrawals are likely to be larger than today’s. Even moderate inflation can noticeably shorten how long money lasts over long horizons.
How to use this tool effectively
- Use realistic spending: Include healthcare, housing repairs, travel, and irregular costs.
- Test multiple return assumptions: Try conservative, base-case, and optimistic scenarios.
- Run a higher inflation case: This is one of the biggest risks to long-term projections.
- Revisit annually: Your real outcome changes as markets, spending, and life plans change.
Example scenario
Suppose you have $500,000, spend $3,500/month, receive $1,000/month from other income, expect a 5% annual return, and model 2.5% inflation. Your initial portfolio withdrawal need is $2,500/month. Over time, inflation raises that number. The calculator projects when the balance may reach zero under those assumptions.
If the result feels shorter than expected, you can improve sustainability by lowering spending, delaying retirement, increasing income, or adjusting your investment strategy with professional guidance.
Why estimates change so much
Sequence of returns risk
Two retirees can earn the same average return but get very different outcomes if bad years occur early. This calculator uses a smooth return path, so your real-world outcome can be better or worse.
Spending flexibility
Fixed spending assumptions are simple, but most households can reduce discretionary spending in weak markets. Even small adjustments can materially extend portfolio life.
Taxes and fees
Taxes, fund fees, advisor fees, and required distributions can all affect net withdrawals. If you want a conservative estimate, lower your expected return to account for these drags.
Ways to make money last longer
- Delay large discretionary purchases during market downturns.
- Increase cash reserves for near-term spending to avoid forced selling.
- Consider part-time or seasonal income for the first years of retirement.
- Rebalance and review allocations to match your risk tolerance and timeline.
- Recalculate after major life events (move, healthcare change, inheritance, etc.).
Frequently asked questions
Is this the same as a safe withdrawal rate calculator?
They are related. A safe withdrawal rate asks what percentage might be sustainable. This calculator asks a time-based question: given your inputs, how long could funds last.
What if my money “lasts beyond the projection”?
That means your assumptions did not deplete the portfolio within the chosen years. It does not guarantee money will never run out; it means the selected horizon was not reached under your input assumptions.
Can I use this for early retirement planning?
Yes. It is useful for retirement planning, financial independence runway planning, and gap-year budgeting. For final decisions, pair it with tax planning and personalized financial advice.
Bottom line
A money longevity calculator is one of the most practical planning tools you can use. The exact number is never perfect, but directionally it helps you answer the question that matters most: “Am I on track, and what changes would improve my odds?”