Monte Carlo Retirement Calculator FAQ
These are the questions readers ask most often about the calculator and the pages around it. Each answer is short on purpose. Where a longer explanation exists, the answer points to the guide that gives it. Every result on this site is what a model produced from stated assumptions, and none of it is advice or a forecast.
The calculator and the score
What is a Monte Carlo retirement calculator?
It is a tool that tests a plan against many random sequences of market returns instead of one average. Each simulated path draws a return for every year, applies your savings and spending, and records whether money lasted. The score counts how many paths finished with money left. Our Monte Carlo simulation retirement calculator is on the home page and is free.
What does the success rate mean?
It is the share of simulated paths in which the money lasted to the age you chose, under the assumptions shown beside the result. A score of 87 would mean 87 out of every 100 simulated paths worked, in that model. It does not say how likely your own retirement is to work, because the model cannot see your life.
Is the score a prediction?
No. It is what the model produced from the inputs and the historical averages it was given, so a different set of assumptions gives a different number. Treat it as one reading to compare against others, and look at what changes it most. The guide on a good Monte Carlo success rate explains why scores differ.
Why does the result move a little each time I run it?
The simulation uses random draws, so two runs with different seeds land close together without matching exactly. More trials narrow that gap, though never to nothing. Differences of a point or two between runs are noise from the draws and not information about your plan. Larger moves come from changing an input.
Data, assumptions and limits
Where do the return assumptions come from?
From a public workbook of annual returns for US stocks, ten-year Treasury bonds and gold, with inflation from a consumer price series. The calculator converts everything to real returns, meaning after inflation, and offers a 1971 to 2025 default and a longer 1928 to 2025 set. The page on how this simulation works lists the statistics and the checks.
What does the calculator leave out?
It steps in whole years, works in real returns, and does not model taxes, health costs, spending shocks or inflation that differs from its history. It also cannot know how you would behave in a bad market. Those gaps are real, and the guide on what a Monte Carlo simulation cannot see covers each of them with the model's own sensitivity results.
Is my information sent or saved anywhere?
No. The calculator runs in your browser and nothing you type is sent from it. The site has no accounts and no forms. If you leave through a partner link, you arrive on another company's page, and that company's own terms and privacy notice apply from there, not ours.
Gold and the partner
What does the gold slider do?
It sets the share of the mix held in gold, and it starts at zero so that gold affects nothing until you move it. When you do, a card shows the score with and without gold and prints the difference with its sign, whichever way it falls. The guide on gold in a retirement portfolio shows the full range.
Will adding gold raise my score?
It might, or it might lower it, depending on what gold is assumed to earn after inflation. In our runs, a gold share raised the score when gold earned what the dataset says and lowered it when gold earned nothing after inflation. The card always states that the answer depends on the assumption.
What does the green Augusta button do, and what is the minimum?
It takes you to Augusta Precious Metals, where you can request a free information kit. The page's consent text mentions phone, text and autodialed contact, and says consent is not a condition to purchase. Augusta states a minimum of $50,000, as stated by Augusta. Pressing the button buys nothing.
How does the site make money?
The site has one partner, Augusta Precious Metals. When a reader asks for Augusta's free kit through one of our buttons and afterwards becomes a customer, Augusta pays the site. Nothing else brings in income. The disclosure on the about page spells this out in neutral terms, and the same notice appears across the site.
Is any of this financial advice?
No. The site explains what a model produced and what history shows. It does not tell you what to buy, sell, hold or spend, and it does not call any plan or score good or bad. The name "Lab" refers to a calculator and not to a credential. For decisions about your own money, ask a qualified professional who can see everything.
How to use these answers
Read the answers as a map and not as a verdict on your plan. The calculator prints a number, and the number only has meaning next to the assumptions that produced it: which years of history, which mix of stocks, bonds and gold, how long the plan has to last, and how much income arrives from other sources. When two tools give different scores for the same person, the difference usually sits in those choices rather than in either tool being wrong. The about page lists where this site's data and methods come from.
Where to go next
If you have not yet run the calculator, start with the inputs on the home page and change one at a time, so you can see which one moves the score. If you already have a number, one useful step is to read how it was built before deciding what it means. The guides are written to be read in any order, and each ends with a short list of pages worth reading next. You can also return to the retirement Monte Carlo calculator at any point and change one input to see what a given answer means in practice.
The questions above are general on purpose. A model like this one cannot answer anything about your specific accounts, taxes or health, and that is the reason the site describes what a model produced and then tells you what to check yourself.
If your question is not answered here, the methodology page is the most detailed account of how the numbers are made, and the guide on gold shows the full set of results for the gold slider, including the cases where gold lowered the score. Both pages state their limits next to their results, which is the habit worth looking for in any retirement tool you use.