Most people think about retirement in two phases: working and saving, followed by stopping and spending. But there is a highly sought-after middle phase that changes everything.
It's called **Coast FIRE**.
What is Coast FIRE?
Coast FIRE is the exact moment your investment portfolio is large enough that, if you never contributed another dollar, it would grow into your full retirement target by age 65 entirely through compound interest.
Once you hit your Coast FIRE number, you don't have to invest for retirement anymore. You can take a lower-paying job, work part-time, or switch to a less stressful career. You just need to 'coast'—earning enough to cover your current living expenses while your retirement portfolio grows on autopilot.
How to calculate your Coast FIRE number
The math requires working backward. You need three things:
- 1Your standard FIRE number (usually 25 times your annual expenses).
- 2Your expected annual return rate (e.g., 7%).
- 3The number of years until you turn 65.
Let's say you spend $40,000 a year, so your FIRE number is $1,000,000. You are 35, so you have 30 years until 65. At a 7% return, a single dollar invested today becomes roughly $7.61 in 30 years.
To find your Coast FIRE number, divide your FIRE target by that growth factor.
| Target (FIRE Number) | Years to 65 | Coast FIRE Number |
|---|---|---|
| $1,000,000 | 20 years | $258,000 |
| $1,000,000 | 30 years | $131,000 |
| $1,000,000 | 40 years | $67,000 |
If you are 35 and aiming for a $1M portfolio, you only need to save $131,000. Once you hit $131,000, you can stop contributing entirely. By 65, at 7%, that $131,000 will have grown into $1,000,000.
Why it's so powerful
Coast FIRE is powerful because it combats burnout. Aggressive saving toward standard FIRE can take 15 to 20 years. But Coast FIRE usually takes just 7 to 10 years.
Hitting that milestone gives you a psychological breakthrough. You no longer need to chase the highest salary. You can take more risks, prioritize flexibility, or spend more time with family.
Standard FIRE is about buying your time back. Coast FIRE is about buying your peace of mind back—years earlier.
The risks
The primary risk is sequence-of-returns risk. If the market performs poorly over the next 30 years, your portfolio might not grow as much as expected. Because you aren't contributing anymore, you can't buy the dip.
To combat this, most people aim to hit Coast FIRE and then continue making small, occasional contributions, or build a larger cash buffer to weather downturns.
Run your own numbers
Where is your Coast FIRE point? Use the calculator below. Enter your current age, target age, expenses, and current savings. Watch the timeline shift as you adjust your savings rate. The moment the portfolio curve crosses the target line is the moment you can stop saving for the future and start living for the present.
Try the mechanism
FIRE Calculator
Enter your own numbers and see the mechanism in action.
Open calculatorEducational information only. This article explains how a mechanism works. It isn't financial advice, a recommendation, or a plan tailored to your situation. Speak with a licensed professional before making any financial decision.