4% Rule / Safe Withdrawal Rate Calculator

4% Rule / Safe Withdrawal Rate Calculator for educational purposes.

Reviewed 2026-08-27

Methodology and sources

This safe-withdrawal planning result is derived only from five visible user-entered scenario inputs: portfolio value, withdrawal rate, planned annual spending, expected annual return, and planning horizon. It supplies no default safe withdrawal rate, market return, tax rate, life expectancy, portfolio path, or financial recommendation.

Planning answer

This page answers what the entered inputs produce under the calculator's documented assumptions. It does not answer what a local provider will charge, approve, diagnose, finance, or guarantee.

Use the result to compare like-for-like scenarios, then replace placeholders with current project records, bids, supplier quotes, authority requirements, or qualified professional review before acting.

Formula in plain English

The calculator multiplies portfolio value by the entered withdrawal rate divided by 100 for annual withdrawal, divides that amount by 12 for monthly withdrawal, and subtracts it from entered annual spending for the spending gap. Portfolio longevity separately uses portfolio value, annual spending, and expected return: when spending is zero or less it returns 100; at an effectively zero return it uses portfolio value divided by annual spending; at a positive return it uses the positive-return sustaining branch or the existing closed-form depletion expression; and at a negative return it uses the same closed-form expression, with a nonnegative floor and final 100-year cap. When years is positive, horizon coverage is the minimum of 1 and longevity divided by years; otherwise it is 1. When withdrawal rate is positive, the spending-capitalized amount is annual spending divided by that rate as a decimal; otherwise it is zero, and its gap is floored at zero after subtracting portfolio value.

Visible assumptions

Portfolio value, withdrawal rate, planned annual spending, expected annual return, and planning horizon are visible user-entered scenario values; none is looked up or inferred from the page title.
The longevity branch assumes one constant nominal annual return and one constant nominal annual spending amount for the entire modeled period.
The 4% in the worked example is a user-entered example value, not a default, endorsed, recommended, or universally safe withdrawal rate.
Withdrawal outputs and the longevity output are separate scenarios: withdrawal uses the entered withdrawal rate, while longevity uses entered spending and expected return.

Worked example

Example user-entered safe-withdrawal planning scenario

Portfolio value: $750,000
User-entered withdrawal rate: 4%
Planned annual spending: $36,000
User-entered expected annual return: 3%
Planning horizon: 30 years

Annual withdrawal = $750,000 x 4% = $30,000; monthly withdrawal = $30,000 / 12 = $2,500; spending gap = $36,000 - $30,000 = $6,000. The separate constant-return and constant-spending expression gives 33.18230708391784 modeled years, so 30-year horizon coverage is min(1, 33.18230708391784 / 30) = 1. The spending-capitalized amount is $36,000 / 4% = $900,000, and its gap over portfolio value is $150,000.

The modeled planning result is a $30,000 annual withdrawal, $2,500 monthly withdrawal, $6,000 annual spending gap, about 33.2 modeled longevity years, 100% horizon coverage, a $900,000 spending-capitalized amount, and a $150,000 gap for these entered assumptions.

Limitations

The deterministic longevity expression does not simulate volatility or sequence-of-returns paths and does not estimate a probability of success.
The model excludes inflation, taxes, investment fees, asset allocation, contributions, account rules, required distributions, pension, Social Security, health costs, and cash or spending shocks.
The 100-year result is a model cap, not evidence of perpetual sustainability, personal life expectancy, or a portfolio lasting for life.
The spending-capitalized amount is an arithmetic alias based on the entered withdrawal rate; it is not a recommended nest egg, suitability finding, or funding requirement.
The cited government sources support planning, disclosure, investment-risk, and longevity boundaries only; they do not support an entered rate, expected return, personal longevity, safe-rate conclusion, or modeled result.
The output is not a universal safe-withdrawal recommendation, retirement-success probability, investment forecast, tax calculation, personalized retirement plan, or financial advice.

Practical next steps

Reconcile portfolio value, planned spending, other retirement income, debt, taxes, fees, and account rules using current records before relying on any scenario.
Compare multiple user-entered withdrawal, spending, return, inflation, and horizon scenarios rather than treating one deterministic result as a forecast.
Use qualified fiduciary, tax, benefits, and legal professionals for decisions that require personal circumstances, account rules, or advice.

Source records

Investor Bulletin: Performance Claims

Publisher: U.S. Securities and Exchange Commission, Investor.gov
Dates: Source dated 2022-09-15; retrieved 2026-08-27
Supports: Official investor context for reviewing performance methodology, fees and expenses, taxes, market conditions, projections, and the limits of return guarantees.
Not price evidence: Does not support an entered withdrawal rate or return, a safe-rate recommendation, a portfolio-success probability, personal longevity, or any modeled result.

Planning for retirement

Publisher: Consumer Financial Protection Bureau
Dates: Source dated 2026-01-06; retrieved 2026-08-27
Supports: Official consumer context that retirement planning can involve debt, income, assets, pensions, Social Security, long horizons, and changing personal decisions.
Not price evidence: Does not support an entered withdrawal rate or return, a spending plan, an investment forecast, personal longevity, or any modeled result.

5 Online Tools You Can Use at Any Age To Plan for a Secure Retirement

Publisher: Social Security Administration
Dates: Source dated 2024-10-03; retrieved 2026-08-27
Supports: Official context that retirement may last decades and that an average life-expectancy estimate omits personal health, lifestyle, and family history.
Not price evidence: Does not support a personal life expectancy, an entered horizon, a safe withdrawal rate, a portfolio-success probability, or any modeled result.

4% Rule / Safe Withdrawal Rate Calculator FAQs

Treat the result as a planning scenario calculated from the values you enter and the configured formula. It is not a quote, approval, or tax or investment advice. Verify the terms that apply to you before making a decision.

Confirm amounts, rates, periods, fees, and eligibility details against dated provider disclosures or other primary documents. Check each value and unit because an incorrect assumption changes the result.

Use dated documents from the lender, provider, or responsible government agency. This calculator compares the values you enter; it does not establish which rate, limit, benefit, or program you qualify for.

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For Creators

CostSignals results are planning estimates based on the values you enter and the calculator’s configured assumptions. Verify current rates, rules, project scope, and quotes independently before making decisions.