Coast Retirement · Research

Safe withdrawal rate explained

A safe withdrawal rate is the percentage of a retirement portfolio withdrawn in the first year of retirement (then adjusted for inflation) while aiming to avoid depleting the portfolio over a long horizon.

What this means

SWR turns annual spending into a portfolio target (FIRE number) and guides drawdown in retirement.

How it works

Annual withdrawal (year 1) = Portfolio × SWR
FIRE Number ≈ Annual spending ÷ SWR

Classic research: Bengen (1994), Trinity Study (1998).

Example

$2M portfolio × 4% = $80k year-one withdrawal. At 3.5% SWR, same spending needs ≈ $2.29M.

Assumptions

Diversified US-heavy portfolio in historical studies
30-year horizon in classic Trinity work
Inflation adjustments on withdrawals

Limitations

Early retirees face longer horizons and sequence risk. Past success ≠ future guarantee.

Common mistakes

Using 4% while retiring at 40 with 50+ year horizons
Ignoring fees and taxes on withdrawals
Confusing SWR with expected return

Related tools

FAQ

What is the 4% rule?

Withdraw 4% in year one of retirement, adjust for inflation thereafter.

Is 4% still valid?

Debated — many FIRE planners use 3–3.5% for longer retirements.

How does SWR relate to Coast FIRE?

SWR sets the FIRE number; discounting sets the Coast number.

What about dynamic spending?

Guardrails and flexible spending can improve outcomes but aren't in the basic rule.

Where to model drawdown?

Drawdown optimizer and full planner.

Explore withdrawal assumptions →

CoastRetirement.com provides educational calculators and planning models. It does not provide individualized financial, investment, tax, or legal advice. Calculator outputs depend on user-provided assumptions and are not guarantees of future results. Consult a qualified professional before making financial or tax decisions.