Will your retirement money last to 95?
A single average return hides the answer that matters. This model grows your savings to 65, then draws down spending net of Social Security to age 95, with both long-run returns uncertain. One click runs 10,000 retirements and tells you the odds your plan survives.
Personal Finance Intermediate Monte Carlo Pro engine
After you install, this is the model to open.
Retirement: Will the Money Last?
- In your spreadsheet, click the Sortia icon in the strip of icons down the right-hand edge. No strip? Click the arrow at the bottom-right to open it. You can also use Extensions, then Sortia, then Open Sortia.
- Click Start from a template and put that name in the search box.
- Pick the card with that name and click Load this template. It arrives on a new tab with real numbers already in it.
This one runs on a Pro engine, and every free install includes five full-quality runs on your own numbers, shared across all five Pro engines rather than five for each. After that, Pro is $199/year.
The answer
At the most-likely returns the plan looks safe. Ten thousand simulated retirements tell a closer story.
- Savings at 65
- $1.68M at most-likely returns
- Chance it lasts to 95
- 60% of 10,000 simulations
- Broke by age 90
- 24% about 1 run in 4
- Worst 1 in 10
- age 86 money gone
At the most-likely returns this plan reaches 65 with $1.68M and still has about $739K at age 95. Run it 10,000 times and it only lasts to 95 in 60% of retirements, and about 1 in 4 is out of money by age 90. The best-guess numbers and the odds disagree, and the odds are what you actually retire on. That is why you simulate a plan instead of averaging it.
The model
Everything is in today's dollars, so both rates are real returns after inflation. The two shaded rates are the uncertain inputs.
| Current age | 50 |
| Retirement age | 65 |
| Current savings | $500,000 |
| Annual contribution | $25,000 / yr |
| Real return, working years | 0% – 5.5% – 9% (uncertain) |
| Real return, retired | -1% – 3% – 6% (uncertain) |
| Retirement spending | $105,000 / yr |
| Social Security | $35,000 / yr |
| Net withdrawal | $70,000 / yr |
Once it is in your sheet
- The model arrives with real numbers in it and runs as it stands, so you can press the button first and understand it second.
- Change the numbers to yours. The sheet marks which cells are inputs and which hold formulas, and most labels carry a note explaining the row.
- Press the run button at the bottom of the panel. It is labeled for the tool you are in, and the result lands on its own tab, with a written reading of it beside the figures.
Never used Google Sheets? Start here goes the whole way, in seven steps, and assumes nothing.
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Every model like this one, and the method behind them: Monte Carlo simulation.