Does Coast FIRE mean I can retire now?

No. It means that under the selected assumptions, today's invested savings could reach a retirement target by a future age without new contributions. You still need income for spending before that age.

Should I use a 4% withdrawal rate?

Treat 4% as an assumption to test, not a guaranteed safe rate. The appropriate rate depends on the retirement length, asset mix, spending flexibility, fees, taxes, and the market paths that occur.

Should Social Security reduce the target?

Dependable retirement income can reduce what the portfolio must fund, but its claiming age and tax treatment belong on the same timeline as spending and withdrawals.

Guide

What Coast FIRE tells you, and what it misses

Coast FIRE asks whether the money already invested could grow to a retirement target without another contribution. The answer is useful only when its assumptions stay visible.

By Steven, Founder · Updated September 3, 2026

Short answer

Coast FIRE means current savings could reach a future retirement target without new contributions; it does not mean retirement can start today.
The number is driven by spending, other income, withdrawal rate, real return, and years to retirement.
Run ranges, then test taxes, income timing, and market sequences in a full projection before changing course.

Illustrative projection

NowRetirementAge 95

Coast FIRE is an accumulation milestone

You reach a Coast FIRE number when today's invested retirement savings could compound to a chosen retirement target by a chosen age without new contributions. It does not mean you can stop working now. It means future earnings would no longer have to fund retirement contributions under the assumptions you entered.

That distinction makes the milestone especially relevant to people decades from retirement. It can frame choices such as reducing hours, changing careers, or redirecting some future cash flow, but it is not a complete retirement plan.

The calculation has two halves

First estimate the annual spending the portfolio must fund at retirement. Subtract dependable income such as Social Security or a pension, then divide the remaining annual need by a withdrawal rate. A $50,000 portfolio-funded spending gap at 4% implies a $1.25 million target in today's dollars.

Then discount that target back to today using the inflation-adjusted return and the years until retirement. With 7% nominal return and 3% inflation, the exact real return is about 3.88%, not 4%. Over 25 years, the $1.25 million target discounts to roughly $482,000 today.

The inputs matter more than the label

A higher expected return, later retirement age, lower spending target, or higher dependable income all reduce the Coast FIRE number. A lower withdrawal rate, higher inflation, or earlier retirement increases it. Small changes compound across decades.

There is no universally correct return or withdrawal rate. Use a range of plausible inputs and keep the result in today's dollars so inflation is not counted twice.

A smooth return is the largest blind spot

The Coast FIRE formula compounds one steady annual return. Real markets do not arrive that way. During accumulation, a poor early sequence can leave the portfolio below the smooth path; around retirement, losses combined with withdrawals can matter even when the long-run average looks acceptable.

Taxes, account types, fees, healthcare, income start dates, and changing spending are also outside the one-number calculation. A whole-life projection puts those events on the timeline and tests many return paths rather than treating the milestone as a finish line.

Related free calculators

Coast FIRE Calculator

Frequently asked

Does Coast FIRE mean I can retire now?: No. It means that under the selected assumptions, today's invested savings could reach a retirement target by a future age without new contributions. You still need income for spending before that age.
Should I use a 4% withdrawal rate?: Treat 4% as an assumption to test, not a guaranteed safe rate. The appropriate rate depends on the retirement length, asset mix, spending flexibility, fees, taxes, and the market paths that occur.
Should Social Security reduce the target?: Dependable retirement income can reduce what the portfolio must fund, but its claiming age and tax treatment belong on the same timeline as spending and withdrawals.

Sources

Compound Interest Calculator — U.S. Securities and Exchange Commission
The future-value compounding relationship used to carry today's portfolio to retirement age.
Accessed September 3, 2026
Determining Withdrawal Rates Using Historical Data — Journal of Financial Planning
Why a withdrawal rate is an assumption grounded in historical sequences, not a guaranteed safe rate.
Accessed September 3, 2026

This is an educational estimate, not tax or financial advice. Figures reflect the law year shown and the inputs you provide. Consult a qualified professional before acting.