Savings Rate → Financial Independence Calculator
How many years does your savings rate buy you? Or what rate does a chosen deadline demand? Real, inflation-adjusted terms, with the 4% rule built in. Nothing you type leaves your browser.
Also available as a desktop app for Windows.
About this tool
The single most useful number in personal finance is not your income or your net worth — it is your savings rate, the share of what you earn that you keep. Spending determines the target you need to hit; saving determines how fast you get there. Both move with the same figure, which is why savings rate carries so much weight: at a 5% real return and a 4% withdrawal rate, someone saving 10% of their pay needs about 51 years to become financially independent, someone saving 25% needs about 32, someone saving 50% needs about 16.6, and someone saving 65% needs about 10.5.
This tool is deliberately real-terms throughout. The withdrawal rate is a real-world rule — the Trinity study's 4% is designed to preserve purchasing power, not to be drawn from a nominal balance — so the return you enter must also be real, meaning after inflation. Entering a nominal 8% against a 4% withdrawal rate quietly assumes you will accept a slow erosion of buying power, which is the most common way this calculation goes wrong. The default of 5% real is a conventional planning figure, not a promise.
Both directions of the question are answered exactly rather than by trial and error. Given your numbers, the years to independence is a closed-form result; given a deadline, the savings rate it demands is too. No simulation, no iteration, and no network — just arithmetic on the figure you typed.
Frequently asked questions
- Why does the savings rate matter more than the return I earn?
- Because it counts twice. Saving more lowers the portfolio you need (spending falls, so the target falls) and raises the amount you add each year. Return only affects the second of those. Going from a 4% real return to a 6% real return is worth a few years; going from a 20% savings rate to a 40% savings rate is worth well over a decade. Return is also not under your control, while savings rate largely is.
- Is the 4% rule reliable enough to plan around?
- It is a planning convention, not a guarantee. It comes from historical US market data over 30-year horizons and assumes a specific stock and bond mix, so it is more fragile for very long retirements and for markets that behave unlike the past. Many people plan with 3.25% to 3.5% instead, which is why the withdrawal rate is an input here rather than a constant. Changing it from 4% to 3.5% raises the target by about 14%.
- Do I enter my income before or after tax?
- Use take-home pay, and keep spending on the same basis. Mixing gross income with net spending is the second most common error in this calculation — it inflates the savings rate by however much you pay in tax. What matters is that the two figures are measured the same way, since the calculator compares them directly to get the amount you actually keep.
- What if I am already past the target?
- The tool says so plainly and reports zero years rather than a negative one. That state means the portfolio alone, at the withdrawal rate you entered, covers your spending — it is a statement about the arithmetic, not advice about whether to stop working, since it says nothing about health care, one-off costs or how your spending might change.
- Why does it refuse to answer when spending exceeds income?
- Because there is no answer to give. If spending is at or above income, nothing accumulates, and no amount of time gets you to independence — the projection diverges rather than converging. Reporting "never" is more honest than reporting a very large number that looks like a date.
- Does anything I type leave the browser?
- No. Every figure is computed in the page: no server, no request, no logging. The tool keeps working with the network switched off, which is a practical way to check the claim yourself.