Finnlight · Free retirement calculator
Coast FIRE calculator
When could you stop saving for retirement and let your investments do the rest? Estimate your Coast FIRE number and the age you could reach it.
Your numbers
Sample values · no sign-up neededExclude home equity and money set aside for other goals.
Today’s dollars, including healthcare.
Today’s dollars; assumed to rise with inflation.
Before inflation, after investment fees.
4% means a target of 25× annual spending.
Your Coast FIRE estimate
All amounts in today’s dollars, before income tax.
- Amount you need invested today to coast
- $478,294
- With your annual contributions, you could coast
- Not by your retirement age
- Retirement savings target
- $1,500,000
- At 65, with no more saving
- $470,422
You are $328,294 below today’s coast target. Future saving and growth could close the gap.
Growth after inflation: 3.88% per year. This is a constant-growth estimate, not a guarantee or a simulation of market risk.
No sign-up to explore. Saving or connecting a bank requires sign-in. The full plan uses its own spending projection, not this withdrawal-rate rule.
Your savings and the coast threshold
The coast threshold rises as retirement gets closer. Where savings with contributions meets it is your estimated coast age; that line assumes you keep contributing until retirement.
Horizontal axis: age · Vertical axis: invested savings in today’s dollars
What is Coast FIRE?
Coast FIRE means you have enough invested that growth alone could reach your retirement savings target, without more contributions. You keep working or use other income to pay today’s bills. It is not the same as being ready to retire now.
FIRE stands for Financial Independence, Retire Early. Coasting can offer more flexibility before full retirement, but future returns, inflation, and spending can change the picture.
How the calculator works
Your retirement target is annual spending divided by your starting withdrawal rate. Your coast number is that target divided by inflation-adjusted growth compounded over the years until retirement.
Real growth = (1 + investment growth) ÷ (1 + inflation) − 1. Contributions are added at each year’s end in today’s dollars. Your estimated coast age is the first whole year your invested balance meets that year’s coast threshold.
Before you stop contributing
A 4% starting withdrawal rate is a rule of thumb, not a promise. Longer retirements, poor early market returns, and higher spending can require more savings. Try lower growth, higher inflation, or a lower withdrawal rate to see how sensitive your estimate is.
This calculator excludes Social Security, pensions, taxes, changing spending, and market volatility. Include healthcare in your spending input. Figures are before income tax — talk to a tax professional about yours. Finnlight is an educational planning tool, not financial, tax, or legal advice.
Content and examples checked · Educational, not personalized advice
Walking through a Coast FIRE number
For a 35-year-old targeting retirement at 65 and $60,000 annual spending, a 4% starting withdrawal rate gives a $1.5 million target in today's dollars. At 7% nominal growth and 3% inflation, real growth is about 3.88%, not exactly 4%. Discounting the target over 30 years gives a coast threshold of about $478,000 today. $150,000 invested without further contributions would grow to about $470,000 in today's dollars under those assumptions, below the target.
Future contributions change when you could reach the coast threshold, not today's threshold itself. The chart's contribution line assumes continued saving through retirement; it is not the path after you stop saving at the coast age. Compare lower growth, higher spending, and a later retirement before changing contributions. Coast FIRE excludes Social Security and does not simulate the withdrawals that follow retirement; use the full plan for that next question.
Continue with How to retire early to explore the next part of this decision.
Common questions
Does the coast number include future contributions?
No. It is the amount needed today without future contributions. Contributions help estimate the first future age you could reach that threshold.
Are the amounts inflation-adjusted?
Yes. Targets and chart balances are in today's dollars. Real growth is calculated by dividing one plus nominal growth by one plus inflation, then subtracting one.
Can I safely stop contributing when the target is reached?
The estimate is not a safety guarantee. Review uncertainty, benefits, spending, and your full retirement projection before changing your saving plan.
Sources and model details: Finnlight assumptions · SSA claiming ages · SSA delayed credits