Retirement & FIRE Calculator
See how long monthly investing takes to reach a savings target.
Enter your current savings, monthly contribution, and expected annual return to find how many years it takes to reach a target such as your FIRE number.
Enter your current savings, monthly contribution, and expected annual return, then pick a target amount. The calculator projects your balance month by month, compounding the return monthly, and reports how long it takes to reach that target. Adjust any input to see how a larger contribution or a higher return shortens the timeline.
Formula & methodology
Each month: balance = balance × (1 + annualReturn/12) + contribution, until balance ≥ target.
Contributions are added at the end of each month and growth compounds monthly. The search is capped at 100 years; returns and inflation are not guaranteed.
Worked example
- $20k now, $500/mo, 6%, target $100k → ≈ 8 years 7 months
Assumptions
- Assumes the same annual return applies every single year; real markets rise and fall unevenly, so actual results will differ from this smooth projection.
- Assumes your monthly contribution stays fixed and is never raised for inflation or a growing income.
- Ignores taxes, fees, and inflation, so the target amount is not adjusted for the falling purchasing power of money over time.
Frequently asked questions
What is a FIRE number?
It is the amount of invested assets that can fund your living costs, often estimated as 25× your annual expenses (a 4% withdrawal rate).
Does it account for inflation?
No. Enter a real (inflation-adjusted) return if you want results in today’s money.
What if my actual returns vary from year to year?
The calculator assumes one constant rate for simplicity. Real returns fluctuate, so treat the result as a rough estimate — try running it again with a lower and a higher return to see a realistic range.
What does the "100-year cap" warning mean?
If the balance still has not reached your target after 100 years of monthly contributions, the calculator stops and shows the balance it would grow to instead. This usually means the contribution or return is too low for that target.
Should I increase my contribution over time?
Doing so shortens the time to your target. The calculator only models a fixed monthly contribution, so re-run it with a higher amount whenever your income grows to see an updated estimate.
Privacy
All processing happens locally in your browser. Your data is never uploaded.
Disclaimer: Projections use a fixed assumed return and are not financial advice. Real returns vary and are not guaranteed.