Coast FIRE Calculator
Determine whether your current savings can grow to your FIRE target by retirement without additional contributions.
Key concepts
Coast FIRE
A milestone where your existing investments can grow on their own to reach your full FIRE number by retirement — you only need to cover current living expenses, not save aggressively.
Coast number
The amount you need today so that, with no further contributions, compound growth will reach your FIRE target by your chosen retirement age.
What this tool does
When Coast FIRE makes sense
If you have already saved enough that time and market returns can carry you to retirement, you may have "coasted" to financial independence. This calculator compares your current savings against that threshold.
Coast FIRE vs regular FIRE
Regular FIRE means your portfolio can support withdrawals now. Coast FIRE means you can stop new retirement contributions because existing assets, left invested, are projected to reach your FIRE number by a chosen retirement age — you still need income for living expenses until then.
Coast FIRE formula
FIRE number = Annual expenses ÷ (SWR / 100) Coast number = FIRE number ÷ (1 + r)^years_to_retirement
Unlike the FIRE calculator (which compounds monthly with contributions), Coast FIRE uses annual compounding with no further deposits: projected balance = current savings × (1 + r)^years. That keeps the coast threshold simple and transparent.
Worked example
Target retirement expenses $40,000/year at 4% SWR → FIRE number $1,000,000. If you have 25 years until retirement and assume a 6% annual return, the coast number is about $1,000,000 ÷ (1.06)^25 ≈ $233,000. If your current savings are above that coast number, this tool reports Coast FIRE achieved under those assumptions.
Common mistakes
- Confusing Coast FIRE with being able to quit work today.
- Using an aggressive return assumption without testing lower rates.
- Forgetting that living costs until retirement still need to be covered from income or other savings.
Methodology on this page
Coast projections use annual compounding and zero future contributions. FIRE number uses the same SWR formula as our FIRE calculator. Values are nominal.
Read the full FinTools4U methodology →Frequently asked questions
What is Coast FIRE?
Coast FIRE means your current portfolio can grow on its own to reach your FIRE target by retirement, so you only need to cover current living expenses.
Does this include inflation?
Not in this version. Values are nominal projections for educational comparison.
How is Coast FIRE different from regular FIRE?
Regular FIRE means you can stop working now. Coast FIRE means you can stop saving for retirement because your existing assets will grow to the target by retirement age.
Sources & further reading
- Investor.gov — Compound Interest — Why time and compounding matter for a coast number.
- William P. Bengen (1994) withdrawal-rate research — Context for the safe withdrawal rate used to define the FIRE target.