Coast FIRE Calculator (2026)
Find the amount you need invested today so compound growth alone carries you to full retirement, with no further contributions.
Calculate Your Coast FIRE Number
Money already invested in retirement and brokerage accounts, in today’s dollars.
What you expect to spend per year in retirement, in today’s dollars.
Leave blank to use 25 times annual spending. Enter a value here to use your own target instead.
Return after inflation. 5% is a common planning assumption; 7% is optimistic, 3% is cautious.
How your savings grow with no further contributions
| Age | Projected balance | Coast number at that age |
|---|
Estimates only — not financial advice. Returns are assumed smooth and constant; real markets vary year to year, and taxes and fees are not included.
What Is Coast FIRE?
Coast FIRE is the point where your invested savings are large enough that compound growth alone will carry them to your full retirement target by your chosen retirement age, even if you never add another dollar. You still need income to cover your living costs, but you no longer need to save aggressively for retirement. That freedom is the whole appeal: many people who reach Coast FIRE switch to lower-paying work they enjoy, go part-time, or simply stop worrying about their retirement savings rate.
Coast FIRE is a milestone on the way to full financial independence, not retirement itself. Hitting your coast number does not mean you can quit work tomorrow. It means your retirement is funded on autopilot, provided your return assumption holds.
The Coast FIRE Formula
The calculation has two steps. First, find your full FIRE number: the nest egg that can support your retirement spending. Under the classic 4% withdrawal rule, that is 25 times your annual spending. Second, discount that target back to today using your expected real return over the years until retirement.
Coast number = full FIRE number / (1 + real return) ^ years to retirement
Projected savings at retirement = current savings x (1 + real return) ^ years to retirement
The formula uses a real return, meaning the return after inflation. That keeps every figure in today’s dollars, so your spending target and your savings stay directly comparable. A commonly used planning range for the real return on a diversified stock portfolio is 5% to 7% a year; cautious planners use 3% to 4%.
Worked Example: Age 30, Retiring at 65, 5% Real Return
| Calculation | Amount | |
|---|---|---|
| Annual retirement spending | $50,000 | |
| Full FIRE number | $50,000 x 25 | $1,250,000 |
| Years to retirement | 65 − 30 | 35 years |
| Coast number | $1,250,000 / 1.05 ^ 35 | $226,613 |
| Current savings | $100,000 | |
| Gap to coast number | $226,613 − $100,000 | $126,613 |
| Projected savings at 65, no further contributions | $100,000 x 1.05 ^ 35 | $551,602 |
With $100,000 already invested at age 30, this saver is about 44% of the way to Coast FIRE. Closing the gap takes roughly $615 a month invested at a 5% real return for 35 years (the $126,613 shortfall grown to retirement is about $698,398, spread over 420 monthly contributions). Once the coast number is reached, contributions can stop and growth alone is projected to reach $1,250,000 by age 65.
How the Coast Number Changes With Age and Return
Two forces move your coast number. Time is the biggest: the fewer years left until retirement, the less compounding can do, so the coast number climbs as you age. Return assumptions matter almost as much: a lower assumed return means you need more invested today. The table below shows the coast number for a $1,250,000 target at different ages and returns.
| Age (retiring at 65) | Years left | Coast number at 5% real | Coast number at 7% real |
|---|---|---|---|
| 25 | 40 | $177,557 | $83,475 |
| 30 | 35 | $226,613 | $117,079 |
| 35 | 30 | $289,222 | $164,209 |
| 40 | 25 | $369,128 | $230,311 |
| 45 | 20 | $471,112 | $323,024 |
| 50 | 15 | $601,271 | $453,058 |
The lesson is clear: starting early is worth far more than saving harder later. A 25-year-old needs only about $178,000 invested to coast to $1,250,000 at a 5% real return, while a 50-year-old needs over $601,000 for the same target.
What Coast FIRE Does Not Cover
- It is not early retirement. Coast FIRE funds a normal-age retirement. Retiring early needs a much larger portfolio, because you stop earning sooner and need the money to last longer.
- It assumes steady returns. Real markets fall as well as rise. A bad decade early on can leave a coasting portfolio short, which is why cautious planners test a lower return, such as 3% or 4%.
- It ignores taxes and fees. Withdrawals from pre-tax accounts are taxed, and fund fees eat into returns. Treat the result as a planning estimate, not a promise.
- It still requires living costs to be covered. Coasting means you stop saving for retirement, not that you stop earning. You still need income for rent, food, and bills until retirement.
