Coast FIRE Calculator
Coast FIRE (Financial Independence, Retire Early) is a milestone where your current savings, growing at your expected investment return, will compound to your full retirement number by the time you retire, with no further contributions required. If your current balance already exceeds your Coast FIRE number, you have officially "coasted." This calculator shows your Coast FIRE number, compares it to your current savings, and projects what your current savings will grow to by retirement, helping you determine whether you can stop or reduce retirement contributions.
Coast FIRE formula
Coast FIRE number = FIRE number / (1 + r)^n
Projected savings = current savings * (1 + r)^n
Reached Coast FIRE: current savings >= Coast FIRE number
The Coast FIRE number is the present value of your FIRE number: how much you need today, growing at rate r for n years, to hit your full retirement target without saving another dollar. If your current savings exceed this number, you have coasted to FIRE.
Coast FIRE milestones and strategy
- Younger investors reach Coast FIRE earlier because they have more compounding time: a 30-year-old with 35 years to retirement needs far less saved today than a 45-year-old with 20 years.
- Coast FIRE gives you freedom to take lower-paying or more fulfilling work knowing your retirement is "on track" from compound growth alone.
- The 4% withdrawal rule comes from academic research suggesting a 4% annual withdrawal from a diversified portfolio has historically survived 30-year retirements. Some use 3.5% or 3% for longer retirements.
- Coast FIRE is a personal milestone, not a regulatory or government concept. The math is straightforward compound growth.
- SSA benefits reduce your FIRE number: if Social Security will cover part of your expenses, your personal portfolio needs less.
Frequently asked questions
What is Coast FIRE?
Coast FIRE is the point at which you have saved enough that, if left to grow without additional contributions, your investments will reach your target retirement number by your planned retirement age. Once you hit Coast FIRE, you only need to earn enough to cover current living expenses, not save for retirement.
How is Coast FIRE number calculated?
Coast FIRE number = FIRE number / (1 + r)^n, where r is the expected annual return and n is the number of years until retirement. This is the amount you need today, growing at rate r for n years, to reach your full FIRE number at retirement without adding another dollar.
What is a FIRE number?
Your FIRE number is the total nest egg that generates enough passive income to cover your annual expenses indefinitely. The most common formula is annual expenses times 25, based on the 4% safe withdrawal rate rule: a portfolio withdrawing 4% per year historically survives 30+ years.
What return rate should I use?
A real (inflation-adjusted) return of 5-7% is commonly used for a diversified stock/bond portfolio. If you use a real return, your FIRE number and Coast number should also be in today's dollars. Using nominal returns requires adjusting all figures for inflation.
What happens after reaching Coast FIRE?
After reaching Coast FIRE, you can reduce or stop retirement savings and work less stressful or lower-paid work that covers only your current expenses. Your portfolio handles itself from that point. Some people use Coast FIRE as a milestone before transitioning to part-time work, freelancing, or a career change.
Official sources
- SSA: my Social Security: Retirement Benefit Estimates
- DOL EBSA: Top 10 Ways to Prepare for Retirement
Reviewed by the CalculatorHub team, edited by James Graham, 15 June 2026. See our methodology.