What return rate should I use in a Coast FIRE calculator?

Most planners use a 5–7% real (inflation-adjusted) annual return. The long-term US stock market averages ~10% nominal, ~7% after inflation. Use 5% for a conservative estimate, 7% as a middle ground. This calculator lets you compare 5%, 7%, and 9% scenarios side by side.

Is Coast FIRE realistic?

For many high savers it is the most realistic FIRE milestone. Example: a 32-year-old targeting $1.25M by 65 at 7% real returns needs only ~$134,000 invested today to coast. The catch: you must leave the money invested and untouched, and actual returns will vary.

Do I stop investing completely after reaching Coast FIRE?

You stop needing to invest for retirement — your portfolio is on autopilot. You still need income to cover current living expenses. Many people switch to lower-stress or more meaningful work at that point, since every dollar earned only needs to fund today, not the future.

Coast FIRE Calculator — Find Your Coast Number

Your numbers

Current age

Target retirement age

Current invested savings $

Annual savings (going forward) $

Used to estimate how many years until you reach Coast FIRE.

Annual expenses in retirement $

Expected real return %

Withdrawal rate %

Your Coast FIRE number

$—

Full FIRE number$—

Years of compounding left—

Coast age—

Years until Coast FIRE—

Shortfall$—

Projected at retirement (coasting)$—

What coasting looks like

Portfolio growth from today to your retirement age — coasting (no more contributions) vs. keep saving.

Coast — no more contributions Keep saving /yr Full FIRE number

How sensitive is your number?

Same inputs, different real returns. This is why the return assumption matters more than precision anywhere else.

Coast FIRE numbers by age

Based on your inputs above. Younger = more compounding = smaller number.

Coast FIRE milestone numbers by age based on your retirement expenses, withdrawal rate, and expected return
Age	Years to retirement	Coast FIRE number	Full FIRE number

What is Coast FIRE?

Coast FIRE is the point where you've invested enough that compound growth alone will carry your portfolio to your full retirement number by your target retirement age — even if you never contribute another dollar. After that, your paycheck only needs to cover today's bills, not your future.

The math is a present-value calculation:

Coast FIRE Number = FIRE Number ÷ (1 + r)ⁿ

FIRE Number = annual retirement expenses ÷ withdrawal rate (e.g. $50,000 ÷ 4% = $1,250,000)
r = expected real (inflation-adjusted) annual return
n = years until your target retirement age

Example: $1,250,000 ÷ (1.07)³³ ≈ $134,000. A 32-year-old with $134,000 invested can stop saving for retirement entirely and still hit $1.25M by 65 at 7% real returns.

Methodology & Assumptions

This calculator determines your Coast FIRE number using the standard present-value discount formula above, calculated entirely in today's dollars. The "years until Coast FIRE" estimate projects how long your current annual savings will take to close any gap, assuming contributions and growth compound at your chosen return rate.

Key Assumptions

Real (inflation-adjusted) returns: The return input represents your expected annual return after inflation. Because calculations are run in real terms, retirement expenses and target portfolio sizes remain denominated in current purchasing power, avoiding the need to predict speculative nominal inflation rates. This input is fully user-adjustable; historical broad-market equity benchmarks provide context, but future returns cannot be guaranteed.
Safe withdrawal rate: The default 4% withdrawal rate is a common planning convention used to estimate the portfolio size required to fund annual living expenses. It is user-adjustable rather than a guarantee.
Taxes and fees: The calculator does not model taxes, account type, advisory fees, fund expenses, or other investment costs. These can reduce the amount available to spend or lower realized returns, so adjust your assumptions accordingly.
Sequence of returns risk & asset allocation: Realized market returns do not arrive in smooth, steady annual increments. Early market downturns, asset allocation choices, and volatility can materially alter retirement readiness and timeline projections.

Estimates are for educational and illustrative purposes only — not individualized financial, tax, or investment advice. Consider consulting a fiduciary financial advisor for personal retirement planning.

Sources & Background

William P. Bengen, "Determining Withdrawal Rates Using Historical Data," Journal of Financial Planning (1994). Bengen analyzed historical retirement periods and found that initial withdrawal rates near 4% were historically sustainable across the scenarios he studied.
Philip L. Cooley, Carl M. Hubbard, Daniel T. Walz, "Retirement Savings: Choosing a Withdrawal Rate That Is Sustainable," AAII Journal (1998). Known as the Trinity Study, analyzing portfolio survival rates across different asset allocations and withdrawal rates.

Neither study proves or guarantees that 4% will always work under all future market conditions.

Last updated: September 27, 2026

Frequently asked questions

What is my Coast FIRE number?

It's the amount you need invested today so that, with zero further contributions, compound growth reaches your full FIRE number by your target retirement age. Enter your numbers above for an instant answer.

How is Coast FIRE different from regular FIRE?

Regular FIRE means saving ~25× annual expenses and fully retiring. Coast FIRE is an earlier milestone: you save enough that compounding finishes the job, then keep working — but only to cover current expenses. You reach freedom decades sooner, without quitting work entirely.

What return rate should I use?

Most planners use 5–7% real (inflation-adjusted). The US stock market has averaged ~10% nominal, ~7% after inflation, over the long term. Use 5% to be conservative. Compare all three scenarios in the sensitivity section above.

Do I stop investing completely after Coast FIRE?

You stop needing to invest for retirement. You still need income for living expenses. Many people downshift to lower-stress or more meaningful work, since each paycheck only has to fund today.

Is Coast FIRE the same as Barista FIRE?

No. Coast FIRE describes how much you've saved (enough to coast). Barista FIRE describes how you live after — working a low-stress part-time job, often for health insurance, while a smaller portfolio compounds. Barista FIRE calculator (coming soon)