Coast FIRE Calculator
Check whether your current investments can grow, with no new contributions, to the portfolio you will need at your coast date, plus the coast number today.
Results · USD
On track?
Projected at coast
- Needed at coast
- $1,000,000.00
- Surplus / shortfall
- -$419,547.33
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Educational estimates · not financial advice · free, no signup
How this was calculated
Needed at coast = annual spend ÷ (SWR/100). Projected = savings × (1 + return)^years. On track if projected ≥ needed.
Want more detail? Full formula notes & FAQs ↓
Detailed guide
What it is, how to use it, how to read the numbers, common mistakes, a worked example, formulas, and FAQs.
What this calculator is
Coast FIRE means having saved enough that, even if you never contribute again, investment growth alone will carry the portfolio to your retirement target by the traditional retirement age. After reaching it you only need to earn enough to cover current living costs, which can allow a lower-stress job or a career change. The calculator projects your current savings forward at an assumed return, compares it with the portfolio needed for your retirement spending at your withdrawal rate, and reports whether you are on track and by how much you are short or ahead. A constant return is an assumption, not a promise, and inflation matters: use a real return or inflate your spending figure so the numbers are comparable.
When to use / who it helps
- You want to know whether you can slow your savings and still retire on time.
- You are considering a lower-paying but more enjoyable job.
- You want a target savings figure for your age.
- You want to test how sensitive the plan is to returns.
- You are comparing different retirement ages.
How to use
Steps
- Enter your current invested savings.
- Enter the expected annual return as a percentage.
- Enter the number of years until the coast date.
- Enter the annual spending you expect in retirement.
- Enter your safe withdrawal rate.
- Read the projected value, the needed value and the shortfall or surplus.
How to interpret results
- Projected is today's savings grown at the return rate.
- Needed is the retirement spending divided by the withdrawal rate.
- A negative surplus means you need more savings or time.
- Using a nominal return with today's spending overstates progress.
- Returns vary, so stress-test with lower rates.
Common mistakes & gotchas
- Using nominal returns with today's dollars.
- Assuming a constant return.
- Forgetting taxes and fees.
- Using an optimistic withdrawal rate.
- Ignoring healthcare costs.
Worked example
Worked example — $150,000, 7% for 20 years, $40,000 spending, 4% withdrawal
- Needed at coast: 40,000 ÷ 0.04 = $1,000,000.
- Projected: 150,000 × 1.07²⁰ ≈ 150,000 × 3.8697 = $580,452.67.
- Shortfall: 580,452.67 − 1,000,000 = −$419,547.33, so not yet on track.
- Coast number today: 1,000,000 ÷ 3.8697 ≈ $258,419, which is the amount that would grow to the target.
Result: At $150,000 the plan falls short by about $419,547; roughly $258,419 would be needed today at a 7% return.
To load the form's own demo values, tap Try example above the Calculate button.
How to calculate / formula
Needed at coast = annual spend ÷ (SWR/100). Projected = savings × (1 + return)^years. On track if projected ≥ needed.
Frequently asked questions
What is coast FIRE?
Having enough invested that growth alone will reach your retirement target.
Is the 7% return realistic?
It is an assumption; real returns vary and may be lower after inflation.
Should I use inflation-adjusted numbers?
Yes, use a real return or inflate your spending.
What does the coast number mean?
The savings needed today to grow to the target without more contributions.
Do I stop saving at coast?
You can, but you still need income for current expenses.
Is this financial advice?
No. It is a planning projection.