Educational estimate only. Real-world returns, taxes, spending surprises, and sequence-of-returns risk can change outcomes significantly.
What this retirement savings longevity calculator does
This calculator estimates how long your nest egg may last after retirement withdrawals begin. It combines your starting savings, expected spending, outside income, investment returns, and inflation into a monthly simulation. Instead of using a rough rule of thumb, it walks month-by-month through what actually happens: your portfolio grows (or shrinks), then supports your retirement cash flow.
The core question is simple: Will my savings last as long as I do? The practical answer depends on a few key variables—especially how much you withdraw, how inflation evolves, and what market returns look like in your first decade of retirement.
How the calculator works
1) Start with your portfolio balance
Your current savings is your retirement “fuel tank.” The larger the starting balance, the more resilient your plan becomes.
2) Subtract your net monthly draw
Net draw = monthly expenses − guaranteed monthly income. If your spending is $5,000 and Social Security plus pension adds up to $2,500, your portfolio needs to cover the other $2,500 each month.
3) Apply expected investment growth
The model assumes a constant annual return converted into monthly growth. Real markets are not smooth, but this approach gives you a useful baseline projection.
4) Increase expenses for inflation each year
Retirement is long. Even moderate inflation can dramatically raise spending needs over 20–30 years. The tool increases monthly expenses annually by your inflation assumption.
How to interpret your results
- If savings run out: the output shows estimated years/months until depletion, your age at that point, and the projected calendar month/year.
- If savings do not run out: the model reports that your portfolio lasted through the selected projection period and shows an ending balance.
- Projection table: you also get annual checkpoints so you can see the trend over time rather than one single number.
Use these results for planning scenarios, not predictions. A smart process is to run conservative, moderate, and optimistic assumptions to create a range.
Inputs explained in plain English
Current age
Used to estimate your age when funds may be exhausted.
Retirement savings
Total amount invested and available to support withdrawals.
Monthly retirement expenses
Include housing, food, transportation, healthcare, travel, gifts, taxes, and recurring subscriptions. Many retirees underestimate healthcare and home maintenance costs—build in realistic buffers.
Monthly guaranteed income
Include Social Security, defined-benefit pension, annuity payouts, rental income you consider dependable, or other recurring cash flow.
Annual return and inflation
Small differences here create major long-term effects. For cautious planning, many people test lower returns and slightly higher inflation.
Ways to make savings last longer in retirement
- Delay Social Security when appropriate to increase lifetime monthly benefits.
- Trim fixed costs (housing, debt payments, insurance inefficiencies).
- Use a flexible withdrawal strategy rather than a rigid fixed-dollar amount.
- Keep a cash buffer for down markets to reduce forced selling.
- Rebalance periodically and align stock/bond mix to your risk tolerance.
- Consider part-time income in early retirement years.
- Plan for healthcare and long-term care before crisis years arrive.
Common retirement planning mistakes
Ignoring inflation
A retirement budget that works today may not work in 15 years. Inflation quietly erodes purchasing power.
Underestimating longevity
Many households now face 25–35 year retirement horizons. Planning only for a short retirement creates real risk.
Overconfidence in steady returns
Markets are volatile. Early poor returns can hurt sustainability even if long-term averages eventually look normal.
Forgetting taxes and one-time shocks
Taxes, major repairs, family support, and medical events are not optional in real life. Stress-test your plan.
Quick retirement longevity checklist
- Run best-case, base-case, and worst-case scenarios.
- Recalculate at least once per year.
- Adjust spending after strong market declines.
- Coordinate withdrawal order across taxable, tax-deferred, and Roth accounts.
- Review beneficiary designations and estate planning documents.
Final thought
The best retirement plan is dynamic, not static. A calculator like this gives you a useful starting map, but your real advantage comes from regular reviews and thoughtful adjustments. If your results look tight, that is valuable information now—when you still have many levers you can pull.