Coast FIRE Number by Age: How Much You Need at 25, 30, 35, 40
Your Coast FIRE number depends heavily on your current age; the younger you are, the less you need invested today because compound interest has more time to multiply your money.
What is the Coast FIRE math behind these numbers?
Assuming a $1 million target retirement portfolio at age 65 and a conservative 7% inflation-adjusted (real) annual return, we can calculate exactly what you need invested at various ages to stop contributing.
The formula for determining your Coast FIRE target at any given age is:
Target Amount / (1 + Real Return)^(Years to Retirement)
For our baseline calculations in this article, we will use the following assumptions:
- Retirement Age: 65
- FI Target Amount: $1,000,000
- Real Return Rate: 7% (historical stock market return adjusted for inflation)
Here is a quick summary table of the required investment at each age milestone:
| Current Age | Years to Grow | Coast FIRE Number | Total Out of Pocket | Compound Interest Earned |
|---|---|---|---|---|
| 25 | 40 years | $66,780 | $66,780 | $933,220 |
| 30 | 35 years | $93,661 | $93,661 | $906,339 |
| 35 | 30 years | $131,367 | $131,367 | $868,633 |
| 40 | 25 years | $184,249 | $184,249 | $815,751 |
| 45 | 20 years | $258,419 | $258,419 | $741,581 |
How much do you need to Coast FIRE at age 25?
At age 25, you have 40 years for your investments to grow before age 65. Using the 7% real return assumption, you would only need $66,780 invested today.
Compound interest is incredibly powerful when given 4 decades to operate. If you manage to save $66k by age 25, a staggering 93% of your ultimate retirement wealth will come from compound interest, not your own contributions. This is why aggressive saving early in your career is the ultimate financial cheat code.
How much do you need to Coast FIRE at age 30?
At age 30, you have 35 years of growth remaining. You would need $93,661 invested today to coast to $1,000,000.
For the average professional, hitting roughly $94k by age 30 is a very realistic goal. It requires saving roughly $800 to $1,000 a month starting at age 22. Once you cross this threshold at 30, you can drop your retirement contributions to $0 and spend that extra $1,000 a month on housing, starting a family, or travel.
How much do you need to Coast FIRE at age 35?
At age 35, with 30 years left, your Coast FIRE number jumps significantly to $131,367.
As you can see, waiting just 5 years from age 30 requires you to save nearly $40,000 more out of pocket. The exponential curve of compound interest means that the later you start, the steeper the climb. However, $131k at 35 is still an incredibly achievable milestone for dual-income households or dedicated savers.
How much do you need to Coast FIRE at age 40?
At age 40, with 25 years until traditional retirement, you need $184,249 invested.
By age 40, you are entering your peak earning years. While the Coast FIRE number is higher, your ability to save large amounts of capital is likely also much higher than it was in your 20s. Achieving this number at 40 means you can safely transition to a lower-stress career for the second half of your working life.
Calculating Your Personal Number
The numbers above assume a generic $1M target and a 7% return. Your personal situation will look different based on your desired spending and risk tolerance.
To find your exact personalized numbers, use our interactive Coast FIRE Calculator. You can adjust the inflation rate, investment returns, and retirement age to build a customized Coast FIRE projection report.