The Math To Reach CoastFIRE In Every Decade

Key Concepts

Coastfire: A financial strategy involving aggressive early saving to reach a portfolio value where future investment growth alone will fund retirement, eliminating the need for further savings.
4% Withdrawal Rate: A commonly used guideline suggesting retirees can withdraw 4% of their portfolio annually without depleting the principal, adjusted for inflation.
Compounding Growth: The process where earnings from an investment generate further earnings, accelerating wealth accumulation over time.
Lifestyle Creep: The tendency for spending to increase as income rises, potentially hindering savings goals.
Inflation Adjustment: Accounting for the decreasing purchasing power of money over time, typically using an assumed annual inflation rate.

Coastfire: A Stage-Based Approach to Financial Independence

This video details the Coastfire strategy – achieving financial independence by front-loading savings and allowing investment growth to cover retirement expenses without further contributions. The analysis breaks down the required portfolio size to achieve Coastfire at different life stages, factoring in inflation, income replacement, and withdrawal rates.

Understanding the Core Assumptions

The calculations presented are based on several key assumptions:

Inflation: A consistent 2% annual inflation rate, aligning with the Federal Reserve’s long-term target. Income projections are adjusted for inflation based on the time horizon to retirement.
Income Replacement: The goal of replacing 80% of pre-retirement income.
Withdrawal Rate: Utilizing a 4% withdrawal rate, a figure supported by extensive portfolio research and considered a “safe” rate to avoid depleting funds during retirement.
Lifestyle Costs: The assumption that lifestyle costs will only increase with inflation. Adjustments are necessary if wage growth exceeds inflation or lifestyle upgrades occur.

Coastfire Targets by Age

The required investment to reach Coastfire varies significantly depending on age and current income. The following details the calculations for ages 25, 35, 45, and 55. All figures are approximate and based on the stated assumptions.

Age 25:

Median Income: $45,000 (adjusted to $99,362 at age 65 with 2% inflation).
Retirement Income Target (80%): $79,489 per year.
Retirement Portfolio Goal (4% Withdrawal): Approximately $1.99 million.
Coastfire Investment Needed Today: $45,126.
Assumed Rate of Return: 9-12%.
Key Takeaway: Time is the biggest asset at this age, allowing compounding to significantly contribute to wealth accumulation. Avoiding lifestyle creep is crucial.

Age 35:

Median Income: $64,000 (adjusted to $115,927 at age 65 with 2% inflation).
Retirement Income Target (80%): $92,742 per year.
Retirement Portfolio Goal (4% Withdrawal): Approximately $2.32 million.
Coastfire Investment Needed Today: $182,670.
Assumed Rate of Return: 8.5%.
Key Takeaway: The window for maximizing compounding is narrowing, requiring a larger initial investment. Balancing life milestones with financial goals is essential.

Age 45:

Median Income: $70,000 (adjusted to $104,000 at age 65 with 2% inflation).
Retirement Income Target (80%): $83,213 per year.
Retirement Portfolio Goal (4% Withdrawal): Approximately $2.08 million.
Coastfire Investment Needed Today: $466,000.
Assumed Rate of Return: 7-12%.
Key Takeaway: Compounding is less forgiving, requiring a larger upfront investment. Risk tolerance may shift, influencing portfolio allocation.

Age 55:

Median Income: $65,720 (adjusted to $80,000 at age 65 with 2% inflation).
Retirement Income Target (80%): $64,000 per year.
Retirement Portfolio Goal (4% Withdrawal): Approximately $1.6 million.
Coastfire Investment Needed Today: $838,000.
Assumed Rate of Return: 6-12%.
Key Takeaway: Limited time for growth necessitates a portfolio size closer to the retirement goal. Honest assessment of current financial standing is critical.

The Role of Compounding and Risk Tolerance

The video emphasizes the power of compounding, particularly in earlier stages of life. As time progresses, the required initial investment increases, and the assumed rate of return may decrease to reflect a more conservative risk tolerance. The presenter notes that lower assumed returns are not necessarily pessimistic, but rather a realistic adjustment to risk appetite.

Important Considerations & Conclusion

The presenter stresses that these figures are guidelines and should be tailored to individual circumstances. Continuous monitoring and adjustments to the plan are recommended. Saving beyond the Coastfire minimum is encouraged to create financial margin and flexibility.

As stated by the presenter, “While personal finance is personal…the exercise builds clarity and coastfire isn't a finish line. So keep checking your plan and saving beyond the minimum to create margin and flexibility.”

Ultimately, Coastfire offers a compelling framework for achieving financial independence by leveraging the power of early saving and long-term investment growth. However, successful implementation requires careful planning, realistic assumptions, and ongoing adjustments based on individual circumstances and market conditions.