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Coast FIRE Calculator
Find the amount you need invested today so that compound growth alone — with no further contributions — can carry it to your retirement number.
Calculate your Coast FIRE number
The formula
FIRE number = annual retirement spending ÷ safe withdrawal rate. Coast FIRE number = FIRE number ÷ (1 + annual return) ^ years until retirement. The longer the runway and the higher the assumed return, the smaller the amount needed today — which is why an optimistic return assumption can make Coast FIRE look deceptively easy. Test a return two points lower before drawing conclusions.
Worked example
Spending of $40,000 at a 4% withdrawal rate needs $1,000,000. With 35 years to grow at 7%, $1,000,000 discounted back is $1,000,000 ÷ 1.07^35 ≈ $93,663. Someone with $50,000 invested at 30 is therefore not yet at Coast FIRE on these assumptions, but continuing to add $500 a month projects to roughly $1,475,835 by 65 — comfortably past the target, if the assumptions hold.
Coast FIRE and dividend income
Coast FIRE is about portfolio size, not income source. Many people pair it with a dividend target for the spending phase: use the dividend income goal calculator to translate a monthly income wish into the capital that would produce it.
Frequently asked questions
What is Coast FIRE?
Coast FIRE is the point where the money you have already invested is projected to grow, with no further contributions, into your full retirement number by your retirement age. After that point, in theory you only need to cover your current living costs.
How is the Coast FIRE number calculated?
First work out your FIRE number: annual retirement spending divided by your safe withdrawal rate. Then discount it back over the years until retirement at your assumed return. That discounted figure is your Coast FIRE number.
What safe withdrawal rate should I use?
4% is the commonly quoted starting point from US retirement research, but it is not a guarantee and may not fit other countries, longer retirements or different asset mixes. Testing 3.5% gives a more cautious target.
Does Coast FIRE mean I can stop saving completely?
Only under the assumptions entered: the return actually materialises, spending stays as planned and no withdrawals are made. Most people treat Coast FIRE as flexibility — the option to earn less or work differently — rather than a finish line.
Does this include pensions or social security?
No. If you expect a pension, subtract its expected annual amount from your retirement spending before entering it here, or treat any pension as an extra safety margin.