Savings Rate Calculator

Why your savings rate sets the date, not your salary

Your savings rate decides how long financial independence takes, and your income barely enters into it. Someone earning $60,000 who saves 40% and someone earning $240,000 who saves the same share both get there in 21.6 years. Their targets are nothing alike, $900,000 against $3,600,000, and the timeline is identical.

The reason is that the rate is doing two jobs at once. Saving a larger share puts more into the portfolio every year, which is the obvious half. The second half is that the target itself is built from spending: whatever you do not save is what retirement has to fund, so raising the rate lowers the finish line while you are running at it. Income raises the amount saved and the amount spent together, so it moves the size of the pot without moving the date.

Say $60,000 of take-home pay against $36,000 of spending: that saves $24,000 a year, a 40% rate. Spending $36,000 needs a portfolio of $900,000 at a 4% withdrawal rate, and getting there from nothing at a 5% real return takes 21.6 years.

The framing is not original to this calculator. It was set out by Mr. Money Mustache as the shockingly simple math behind early retirement, and the table below is that relationship recomputed by this site rather than reproduced.

How many years until financial independence?

At a 5% real return and a 4% withdrawal rate, starting from nothing, this is what each savings rate costs in years. Read the two columns against each other rather than down either one: the rate rises in even steps while the years collapse.

The shape of that column is the argument. Going from 10% to 20% removes 14.6 years; going from 70% to 80% removes 3.2 years, but by then there are only 5.6 years left to remove. Every ten points of savings rate buys progressively less time in absolute terms and progressively more as a share of what remains, which is why early increases feel slow and later ones feel sudden.

Two limits on it. It assumes one return repeated annually with no bad decade in it, which makes it arithmetic rather than a forecast, and it starts from nothing, so it describes no particular reader. Entering your own figures in the calculator above applies whatever is already invested, which is the one input that breaks the rate-alone relationship. Open the calculator on a 50% savings rate to see the middle of the table with real numbers attached.

What savings rate do I need to retire in 10 years?

About 66.5% of take-home pay, at the same 5% real return and 4% withdrawal rate, starting from nothing. That is the table above read backwards, and because the relationship inverts exactly it is solved rather than estimated between the rows.

Short horizons ask for rates most people cannot reach on their current spending, which is worth seeing plainly rather than discovering slowly. The usual response is to treat the rate as fixed and the horizon as the answer, which is what the calculator above does by default. Open the calculator on the ten-year rate to see what that plan looks like against a real income.

These figures start from nothing, so anyone with money already invested needs less than the table says. That head start is the subject of the next section, and it is the main reason two people saving the same share can finish years apart.

What moves the answer

Three inputs change the timeline, and they do not carry equal weight. The return assumption matters most because it compounds, the withdrawal rate sets the size of the target, and anything already invested subtracts from the beginning rather than the end.

The expected return. It is applied every year, so a small disagreement becomes a large one over decades. Dropping the example on this page from 5% to 3% moves it from 21.6 years to 25.5 years. The figure entered is already a REAL return, above inflation; see how mixing real and nominal rates breaks a projection for why that distinction matters.

The withdrawal rate. It does not affect how fast the portfolio grows at all. It decides how large it has to get. Moving from 4% to 3% raises the example target from $900,000 to $1,200,000 and the wait to 25.7 years. Which rate survives a real retirement is a separate question from this arithmetic, and the historical FIRE simulator is where it gets answered against market data rather than assumed.

Money already invested. This is the one input that makes income matter, because a head start is only meaningful relative to what you earn. Starting the example with $60,000 already invested, one year of take-home pay, shortens it from 21.6 years to 19.2 years. If you have reached the point where the existing balance alone would grow into your target, the coast FIRE calculator answers that question directly.

Earning more is the usual first move, and it raises the rate only if the extra is saved rather than spent. If spending rises with income the date does not move at all. That is not an argument against a raise. It is the reason the rate rather than the salary is the number worth tracking.

What this calculator does not model

The list below is short on purpose: each omission trades precision for a rate anyone can recompute by hand.

• A raise, or a pay cut: Income is held flat in real terms for the whole period. Most careers do not work that way, and a rising income raises the rate only if spending stays put, which is the assumption that usually breaks first.
• Tax, and which account the money sits in: Everything is net and every account is one pot. Money locked in a retirement account until a set age counts the same here as money you can reach next week, and for a plan aiming at independence well before that age the difference is substantial.
• One steady rate, not a real sequence: Every year compounds at the same assumed rate. Two savers who average the same return over the same years can still finish at different totals, because the order in which gains and losses arrive changes what compounding does along the way.
• Spending that changes after you stop: The target assumes retirement costs what life costs now. Commuting and childcare fall away for some people while health costs and travel rise for others, and the model takes no view on which applies.
• State and workplace pensions: No later income of any kind is counted. Any of it reduces what the portfolio has to cover from the age it begins, so leaving it out is the cautious direction rather than the flattering one.

A savings rate alone does not capture income growth or the equity a mortgage builds over time, which is where the full FIRE plan picks up: it adds both, plus a year-by-year path. For a rate that is not steady, the lifestyle change calculator models a career break or a period of lower income directly, and the FIRE simulation replays a finished plan against more than 150 years of market history.