Coast FIRE Calculator

The FIRE variant that's actually most people's best option

Coast FIRE is financial independence achieved when your current portfolio, growing untouched at expected market returns, will reach your retirement target by your chosen retirement age — without any additional contributions. Once you hit the Coast FIRE number, you can stop retirement contributions and focus on covering current expenses. The portfolio coasts to its target through compounding alone. For most people, this is far more achievable than full FIRE and comes 10-20 years earlier in life.

The Coast FIRE math

Coast FIRE number = Target retirement pot / (1 + r)^n, where r is expected real return and n is years to traditional retirement age. For someone aiming at 1m at age 65:

Age 30: Coast FIRE number = 1m / (1.06)^35 = 130,000. Save 130,000 by 30, stop contributing, pot reaches 1m at 65 at 6% real growth.

Age 35: 1m / (1.06)^30 = 175,000.

Age 40: 1m / (1.06)^25 = 233,000.

Age 45: 1m / (1.06)^20 = 312,000.

Age 50: 1m / (1.06)^15 = 417,000.

The required amount roughly doubles every 12 years of delay. Someone at 30 who hits Coast FIRE has a fundamentally different life ahead than someone who hits it at 45 — both will retire with similar amounts, but the earlier person has 35 years of reduced financial pressure to enjoy while the later person has 20.

Why Coast FIRE feels different

Full FIRE requires you to replace employment income entirely; Coast FIRE just requires you to cover current expenses without needing to save further. For most households, covering current expenses from any job is dramatically easier than saving 40-50% of income. Coast FIRE therefore opens up career flexibility: you can take a part-time role, a passion-project job at lower pay, freelance work with variable income, time off to raise children, or a mid-career pivot that involves a salary drop. None of these options are viable under "save aggressively toward full FIRE"; all of them become available once you hit Coast FIRE.

The implicit assumptions that matter

Coast FIRE math depends on return assumptions holding over decades. Two failure modes:

Lower-than-expected returns. If your 6% assumption delivers 4% actual, a 130,000 Coast FIRE pot at age 30 reaches 517,000 at 65 rather than 1m. The coast plan undershoots by 50%. Conservative Coast FIRE math uses 4-5% real return assumptions rather than historical averages, providing margin against return disappointment.

Sequence of returns early. If markets crash shortly after you hit Coast FIRE, the subsequent years of growth start from a lower base. A 30% drop at age 31 means the remaining compounding happens on 70% of your Coast FIRE number — undershooting the target by 30% even if subsequent returns match expectations. This is why some Coast FIRE practitioners continue modest contributions during bear markets even after technically hitting the number — to cushion sequence risk.

The spending-coverage question

Coast FIRE frees you from retirement saving but not from current expenses. If your Coast FIRE number is 130,000 and your current annual spending is 35,000, you still need to earn 35,000/year from somewhere. This usually means working at a job, but the job doesn't need to fund retirement — it just needs to fund lifestyle. That's a much lower bar. The jobs that cover 35,000/year are numerous and include many lower-stress, higher-flexibility, lower-commute, or more-meaningful options than the higher-paying jobs required to save aggressively for full FIRE.

Coast FIRE with a spouse

Two-income households have a structural advantage with Coast FIRE because only combined current expenses need to be covered. A couple hitting Coast FIRE means neither partner needs to work full-time if the two part-time incomes cover expenses. One can pursue a passion while the other covers; both can pursue passions if each income covers half of expenses. This optionality is often the underappreciated benefit — Coast FIRE delivers flexibility more than it delivers retirement.

The CoastFI vs BaristaFIRE distinction

Related but distinct concepts:

Coast FIRE: Portfolio covers retirement if left to grow. Any current income is sufficient for current expenses.

Barista FIRE: Portfolio plus part-time work provides complete retirement income. The part-time job contributes during retirement, not just during accumulation.

Coast FIRE is an accumulation-phase milestone. Barista FIRE is a retirement strategy. Someone can pass through Coast FIRE toward full FIRE, then retire early and implement Barista FIRE for psychological or financial safety-margin reasons. The concepts layer rather than compete.

The catch with Coast FIRE and early retirement

Coast FIRE assumes you retire at traditional age (65) to collect the coasted pot. To retire earlier than the coast-fire date, the savings level required is more than Coast FIRE (covering expenses between stopping work and the pot becoming accessible) or a bridge from other savings. Coast FIRE alone doesn't fund early retirement — it just funds traditional-age retirement with no additional contributions required. This is why the "I hit Coast FIRE at 35" narrative often includes "and I kept contributing anyway because I want to retire at 55".

Psychological benefits beyond the math

The highest-value aspect of Coast FIRE is often psychological, not mathematical. Knowing that "my retirement is handled" removes a source of ongoing financial anxiety. Career decisions change — you can prioritise meaningful work over salary, take risks on entrepreneurship, or reduce hours without catastrophic consequences. Relationship dynamics shift — you're no longer saving toward an abstract target that dominates household financial discussions. For many people, Coast FIRE produces a more significant quality-of-life improvement than the eventual full-retirement-financial-freedom does, precisely because it arrives earlier in life.

Coast FIRE as a stepping stone

The most common Coast FIRE pattern: accumulate aggressively in 20s and early 30s; hit Coast FIRE around 35-40; transition to lower-stress or more-flexible work; let the pot coast while enjoying less-pressured career years; reach full FIRE around 50-55 even without significant additional contributions; retire somewhere between 55 and traditional retirement age. This pathway treats Coast FIRE as a milestone rather than a destination, while using the milestone to enable career and life choices that full-FIRE focus wouldn't allow.

What this calculator shows

The tool computes the portfolio size required today to reach a retirement target without further contributions, given expected return and years remaining. It doesn't model sequence risk, partial contributions after Coast FIRE, or the interaction with current spending. Use the figure as a planning milestone; verify the return assumption is conservative; build in some margin for sequence risk if Coast FIRE arrives early in a market peak.