How the calculator works
The number. Monthly spending × 12 × your multiplier. 25x is the 4% rule written the other way round: one divided by 0.04 is 25. The multiplier is the decision that moves the answer most, which is why the result shows the same spending at 25x, 28x, 30x and 33x side by side.
The year. What you have today compounds once a year at the return you set, a year of savings is added at the end of each year, and the first year the total meets your number is your year. It looks up to 60 years ahead and says so if the number is not reached. It is the same calculation the FIRE page inside Networo runs, from the same code. One difference in what goes in: here you enter your invested money, while the FIRE page inside Networo starts from your whole tracked net worth, so if you track a home there, its year can come out earlier than the one here.
Where 4% comes from. The Trinity Study (Cooley, Hubbard and Walz, 1998) tested withdrawal rates against US market history over retirements of up to 30 years. Someone retiring at 40 is planning for a longer stretch than the study covered, which is why people aiming at early retirement often use 3% to 3.5%, which is roughly 28x to 33x. The reasoning is in the 4% rule, honestly.
Which multiplier
| Multiplier | Withdrawal rate | Suits |
|---|---|---|
| 25x | 4.0% | A roughly 30 year retirement, no dependents, some flexibility to earn again |
| 28x | 3.57% | College costs, children, a longer safety margin |
| 30x | 3.33% | A 40 year retirement or more, irregular expenses, one income |
| 33x | 3.0% | Maximum buffer, uncertain healthcare, very long retirement |
On $48,000 of spending the gap between 25x and 30x is $1,200,000 against $1,440,000. Use what you expect to spend in retirement, not what you spend now, and leave out a home you plan to keep living in.
Questions
How is my FIRE number calculated?
Your expected annual spending in retirement, multiplied by your chosen multiplier. The classic multiplier is 25, which is the 4% rule written the other way round: one divided by 0.04 is 25. Spend $4,000 a month, which is $48,000 a year, and 25x gives $1,200,000. The calculator also shows the same spending at 28x, 30x and 33x, because the multiplier is the decision that moves the answer most.
How is the year worked out?
It compounds what you have today once a year at the return you set, adds a year of your savings at the end of each year, and stops at the first year the total is at or above your FIRE number. It is the same calculation the FIRE page inside Networo runs, from the same code, and it looks up to 60 years ahead. If the number is not reached inside 60 years the calculator says so rather than guessing. One difference: here you enter your invested money, while the FIRE page inside Networo starts from your whole tracked net worth, so if you track a home there, its year can come out earlier.
What return should I assume?
The calculator starts at 7% a year, which is the default the Networo FIRE page starts with too, before inflation. Networo's own projection uses 5% as its cautious case and 9% as its optimistic one. Try all three. A real portfolio does not return its average every year, and the order of good and bad years matters, which is why the number here is a target, not a promise.
Should I include my house?
Only if you intend to sell it or borrow against it. A home you plan to live in produces no income, so counting it makes the target look closer than it is. Most people track it in their net worth but leave it out of the invested figure they enter here, and keep the mortgage in their spending until it is paid off.
Is anything I enter saved?
No. The calculation runs in your browser, there is no account and no email, and the figures never leave the page. No figure you enter is recorded. The page counts that a calculation was completed, with none of the numbers attached, and the page view is counted the way it is on every page of this site.
What do I do once I know my number?
Watch the gap close. A free Networo account lets you record your assets and liabilities by hand, keeps every update as a dated snapshot, and shows your years to FIRE against your real figures as they change. Bank login is never required. Pro adds a Monte Carlo view that runs 1,000 simulated market paths instead of one average.
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