Coast FIRE Calculator

What Coast FIRE means

Coast FIRE is a milestone on the way to financial independence, not financial independence itself: the point where your current portfolio, growing untouched at expected market returns, will reach your retirement target by your chosen retirement age without any additional contributions. Past that point, retirement contributions can stop and income only needs to cover current expenses; the portfolio coasts to its target through compounding alone. Because the threshold is a fraction of the full FIRE target, it typically arrives years earlier in a working life.

The Coast FIRE math

Coast FIRE number = full FIRE target / (1 + r)^n, where the full FIRE target is annual retirement expenses divided by the safe withdrawal rate, r is the expected real return, and n is years to the chosen retirement age. For a 1.5m target at age 65 with a 7% return, the ladder runs:

Age 30: 1.5m / (1.07)^35 = 140,500. Reach that by 30, stop contributing, and the pot compounds to 1.5m at 65.

Age 35: 1.5m / (1.07)^30 = 197,100.

Age 40: 1.5m / (1.07)^25 = 276,400.

Age 45: 1.5m / (1.07)^20 = 387,600.

Age 50: 1.5m / (1.07)^15 = 543,700.

At a 7% assumption the required amount roughly doubles every 10 years of delay. Someone who reaches the number at 30 and someone who reaches it at 45 retire with similar pots. The difference is how many working years each spends with the retirement question already settled.

How Coast FIRE changes the working years

Full FIRE requires replacing employment income entirely; Coast FIRE only requires covering current expenses without further saving. For most households the second bar is much lower than sustaining a 40–50% savings rate. That difference is what opens up part-time roles, lower-paid work that means more, freelance income that varies month to month, time out to raise children, or a mid-career change involving a pay cut. Options like these sit awkwardly with an aggressive full-FIRE savings plan; past the Coast FIRE threshold they become easier to justify.

Where the assumptions can break

Coast FIRE math depends on a return assumption holding over decades, and it can fail in two distinct ways.

Lower-than-expected returns. If the 7% assumption delivers 5% actual, the age-30 pot from the ladder above reaches about 775,000 at 65 rather than 1.5m, roughly 48% short. This is why some Coast FIRE calculations are run at 4–5% real returns rather than historical averages: the lower assumption builds in margin against return disappointment.

Sequence of returns early. A market crash shortly after reaching the threshold means the remaining decades of growth start from a lower base. A 30% drop the following year leaves compounding to work on 70% of the number, undershooting the target by a similar margin even if later returns match the assumption. Some practitioners keep contributing through bear markets after technically reaching the number, as a cushion against exactly this.

Covering current expenses

Coast FIRE frees income from retirement saving, not from living costs. Take the age-30 figure from the ladder above (140,500) alongside current spending of 35,000 a year: that 35,000 still has to come from somewhere, usually a job. The difference is that the job no longer needs to fund retirement, only lifestyle, and the set of jobs that cover living costs is far larger than the set that also supports aggressive saving.

Coast FIRE with a partner

Two-income households have a structural advantage: only combined current expenses need covering once the threshold is reached. Neither partner needs full-time work if two part-time incomes cover the bills, or one can carry the expenses while the other pursues lower-paid work. The flexibility, more than the retirement date, is often what the milestone actually delivers.

Coast FIRE and Barista FIRE

The two are related but distinct. Coast FIRE: the portfolio covers retirement if left to grow, and any income source that covers current expenses will do. Barista FIRE: the portfolio plus ongoing part-time work together provide retirement income; the part-time job contributes during retirement, not just before it. Coast FIRE is an accumulation-phase milestone; Barista FIRE is a retirement strategy. Someone can pass through Coast FIRE, retire early, and then run a Barista FIRE arrangement; the concepts layer rather than compete.

Retiring before the coast date

The coasted pot arrives at the retirement age entered into the calculator: 65 in the examples here, though pension and account access ages differ by country, so that age is an illustration rather than a rule. Stopping work earlier than the coast date needs more than the Coast FIRE number: either a larger pot, or a separate bridge fund covering the years between stopping work and the pot becoming accessible. Coast FIRE alone funds retirement at the chosen age with no further contributions, and nothing earlier. That is why someone who reaches the number at 35 and wants to stop at 55 typically keeps contributing anyway.

The psychological side

For many people the psychological effect is the larger one. Knowing the retirement question is settled removes a standing source of financial anxiety, and career decisions change shape: meaningful work can outrank salary, entrepreneurial risk becomes survivable, reduced hours stop feeling reckless. The benefit arrives in the middle of a working life rather than at the end of it, which is a large part of why the milestone carries the weight it does.

When savings already exceed the number

If current savings are above the Coast FIRE number, the calculator shows the surplus rather than a gap, and the status row reads accordingly. A surplus means the pot is on course to overshoot the target at the chosen age; equivalently, the same savings support an earlier retirement age, a lower return assumption, or higher retirement spending. Re-running the calculator with those inputs adjusted shows which of the three the surplus could absorb.

A common Coast FIRE pattern

One pattern the concept supports: accumulate hard in the 20s and early 30s; reach the threshold around 35–40; shift to lower-stress or more flexible work; let the pot coast; arrive at full FIRE in the 50s without significant further contributions. Treated this way, Coast FIRE is a milestone that shapes the middle of a career rather than a destination in itself.

What this calculator shows

The tool computes the portfolio size required today to reach a retirement target without further contributions, given the expected return and years remaining, and the gap or surplus against current savings. It doesn't model sequence risk, partial contributions after the threshold, or the interaction with current spending. Because the result hinges on the return assumption holding over decades, the margin between assumed and achieved return decides whether the pot actually arrives, most visibly when the threshold is reached near a market peak.