Coast FI & FIRE Inflection Points
From optional savings to full financial independence, visualize the key milestones on your investment journey.
How this works
Growth is projected using the real (inflation-adjusted) return — the nominal annual return you enter (default 7%), deflated by your inflation input (default 2.5%) — compounded monthly, and every dollar figure is shown in today's purchasing power rather than future inflated dollars.
Tracks three milestones on the same real-return simulation: the FI crossover (savings reach your FI number), Coast FI (savings are already enough that, with zero further contributions, they'd grow to your retirement nest egg by your target retirement age), and the principal-vs-gains crossover (investment gains exceed total money put in).
The chart runs a few years past your target retirement age; the underlying search for each milestone runs to age 100 so a late-but-reachable FI date is still reported rather than shown as unreachable.
Key assumptions
- FI/Coast FI target = desired annual retirement income / safe withdrawal rate (default 4%).
- An optional toggle stops contributions once Coast FI is reached, letting you see the no-further-savings path to retirement.
What this leaves out
- Sequence-of-returns risk — growth is a constant rate, not a real market path.
- Fees — expense ratios and advisory fees are not deducted from the return.
- Taxes in retirement — withdrawals are treated as spendable in full; account type (traditional, Roth, taxable) is not modeled.
- Income growth — savings and contributions stay flat in real terms.
- Irregular spending — no college costs, home purchases, medical shocks, or windfalls.
Related calculators
A worked example: three milestones on one savings path
A 30-year-old with $25,000 invested, saving $1,000 a month, targeting $60,000 of annual spending at a 4% withdrawal rate and a retirement age of 65. The FI number is $1,500,000 in today's dollars, and full FI arrives in 50.8 years — age 80, well past the target retirement age.
The Coast FI number is far smaller: $323,578. That is what this saver would need invested today, at 30, for 35 years of compounding at the real return to land on $1,500,000 by 65 with no further contributions at all. The gap between $323,578 and $1,500,000 is the compounding not yet collected, and it is why the Coast FI milestone is so much more reachable than full FI — and why it shrinks as a share of the target the older you are when you start.
The third milestone is the principal-vs-gains crossover, which lands in year 23. That is when cumulative investment gains ($228,211) first exceed everything put in ($190,000 of contributions plus the original $25,000). Before it, the portfolio is mostly your savings; after it, the portfolio is mostly the portfolio's own work — the point where the plan stops depending primarily on your paycheck.
Frequently asked questions
What is Coast FI?
Coast FI is the balance that, left alone with no further contributions, grows to your full retirement number by your target retirement age. Reaching it does not mean you can stop working — you still need income to cover current living costs — it means you can stop saving for retirement. It is computed here as your retirement nest egg discounted back at the real return over the years between your current age and your target retirement age.
Is Coast FI different from Barista FI?
Yes, though they are often used loosely. Coast FI has a precise arithmetic definition: enough invested that compounding alone reaches your retirement number on time. Barista FI is a weaker and vaguer condition — enough invested that part-time work, often taken for the health insurance, covers the gap between reduced income and expenses. Coast FI is a balance you can calculate; Barista FI depends on what job you could get.
Why is full FI so much further out than the Coast FI number suggests?
Because they are different targets, not different speeds. Coast FI asks only for a balance that compounding can carry to $1,500,000 by age 65. Full FI asks for the $1,500,000 itself, and getting there on $1,000 a month takes 50.8 years on these inputs. Coast FI is the milestone that says your retirement is safe; full FI is the one that says you can stop working. Do not read the first as the second.
What does the principal-vs-gains crossover actually tell me?
It marks the year your money starts out-earning your contributions — here, year 23, with $228,211 of gains against $190,000 contributed. It has no bearing on when you can retire, so do not plan around it. What it is good for is calibrating patience: the crossover is slow to arrive and there is no way to shortcut it, which is a useful antidote to expecting compounding to feel dramatic in the first decade.
Why does the chart stop before the FI date?
The chart runs to a few years past your target retirement age, since that is the range most decisions live in, but the underlying search for each milestone runs to age 100. A late-but-reachable FI date is reported as a number rather than shown as unreachable, so the crossover figure can sit well beyond the right edge of the chart — as it does at 50.8 years here.
Sources
- Determining Withdrawal Rates Using Historical Data
William P. Bengen, 1994, Journal of Financial Planning — checked 2026-08-12
The paper that established the '4% rule' — the foundational research this site's safe withdrawal rate defaults trace back to.
- Retirement Savings: Choosing a Withdrawal Rate That Is Sustainable
Philip L. Cooley, Carl M. Hubbard, Daniel T. Walz, 1998, AAII Journal — checked 2026-08-12
The 'Trinity study,' which expands on Bengen across a range of withdrawal rates and portfolio mixes. Only Table 3 in the original paper is inflation-adjusted — the commonly-quoted near-100% success rates come from the nominal-withdrawal Tables 1-2.
- Safe Withdrawal Rate Series
Big ERN, Early Retirement Now — checked 2026-08-12
A practitioner blog, not peer-reviewed — the most detailed public research on SWR sensitivity to horizon length and asset mix.
- State of Retirement Income: 2025
Morningstar — checked 2026-08-12
Forward-looking base-case starting withdrawal rate, cited for context alongside the fixed 4% default this site uses. The ~3.9% figure is search-attested rather than directly confirmed against the source — treat it as a data point, not a recommendation, and worth checking whether a newer edition has superseded it.
*The calculations provided are for illustrative purposes only and should not be considered financial advice. Please consult with a qualified financial professional before making any decisions.