4 Percent Rule: Test Early Spending Against a 30 Year Plan
Learn how the 4 percent rule sets a first year withdrawal, adjusts for inflation, and fits your plan with scenario tests and behavioral support.
It is a widely used rule of thumb built on historical returns for a roughly 30-year retirement, so treat it as a starting point, not a guarantee. Below, we show how to compute it, test it, and adapt it to your situation.
TL;DR:
Withdraw 4% of your initial portfolio in year one, then raise that dollar amount with inflation each year, regardless of market performance.
The historical benchmark assumes a diversified stock and bond portfolio, a 30 year horizon, and steady real spending; it cannot guarantee future results.
An early market drop can force sales at low prices and shrink recovery potential; cash buffers, spending cuts, or partial annuities can reduce that pressure.
Early retirees or cautious savers can start at 3% to 3.5%, while guardrails or withdrawals based on current balance trade steadier income for flexibility.
Review the plan yearly and after major market or life changes, taking preemptive action if withdrawals rise 25% above the initial withdrawal rate.
Table of Contents
What assumptions and limits should you check before using 4 percent?
Why does asset allocation change how safe your withdrawals are?
How does the 4 percent rule work in practice?
The formula is simple: first-year withdrawal = portfolio value × 0.04. The SEC’s summary guidance describes the same approach: multiply the value of all your investments by 4% to get the first-year amount, then each year increase that dollar figure by the rate of inflation.
Say you retire with $800,000 (an illustrative figure). Year one: $800,000 × 0.04 = $32,000. If inflation runs at 3% (also illustrative), year two is $32,000 × 1.03 = $32,960. Year three, with 2% inflation, is $32,960 × 1.02 = $33,619.20.
Here is the part people get wrong. After the first withdrawal, the rule runs on inflation adjustments alone, regardless of what the market does.
To replicate this in a spreadsheet or calculator:
Add up your investable assets on the day you start withdrawing.
Multiply that total by 0.04 to get your year-one withdrawal.
Look up the inflation rate for the year that just ended.
Multiply last year’s withdrawal by one plus that rate.
Repeat step 4 every year and compare the result against your actual spending.
Track your balance alongside, so you can see whether the plan holds up.
Where did the 4 percent rule come from?
The rule traces back to financial planner William Bengen, who ran historical rolling-window tests on stock and bond returns. Bengen’s analysis, part of the lineage that led to the Trinity Study, used rolling 30-year periods.
The Trinity Study then brought the idea to a wide audience by testing withdrawal rates across different mixes of stocks and bonds. Since then, researchers have revisited the rule, offered refinements, and raised critiques.
Bengen’s work: rolling historical windows produced the 4% figure for a 30-year horizon.
Trinity Study: tested withdrawal rates against different asset mixes and made the benchmark famous.
Later research: refined the rule and questioned whether a fixed rate suits everyone.
Bengen’s own refinement: he later suggested pre-emptive action if your withdrawals climb substantially above the initial rate, a point we return to in the checklist below.
The data it rests on cover specific periods, specific portfolios and a specific time horizon.
What assumptions and limits should you check before using 4 percent?
Before you borrow the number, check that your situation looks like the one the studies modelled.
A diversified portfolio: the studies used mixes of stocks and bonds, not a single holding or all cash.
A 30-year horizon: if you retire early, you may need your money to last longer. The Social Security Administration’s longevity data and CDC mortality statistics show why horizon matters: people are living longer, and more of us reach advanced ages.
Constant real spending: the rule assumes you spend the same inflation-adjusted amount every year, with no big lumps for healthcare or home repairs.
No guaranteed outcome: the rule describes what worked historically, not what must happen next.
The biggest threat is sequence of returns risk. If markets fall hard in your first few years, you sell more shares at low prices to fund a fixed-dollar withdrawal. That leaves less invested to recover when markets rebound. Two retirees can earn the same average return over 30 years and end up in very different places, simply because of the order in which the good and bad years arrived.
Critics also point to low bond yields, which could make the historical mix less generous going forward. On the other side, the rule can be inefficient: in many historical scenarios, retirees finished with a large leftover balance, meaning they could have spent more.
Pro Tip: Run your own plan against a bad early stretch, not just the average. If the plan survives that, you can retire with more confidence.
How do you calculate 4 percent for your own portfolio?
Let’s put numbers on it, using illustrative portfolios and an illustrative 3% inflation rate.
Illustrative portfolio: multiply its value by 0.04 for the first-year withdrawal, then adjust that amount by inflation for the next year.
Illustrative portfolio: multiply its value by 0.04 for the first-year withdrawal, then adjust that amount by inflation for the next year.
Constant real dollars versus 4% of the current balance: suppose the portfolio falls after year one. Under the standard rule, the next withdrawal is based on the initial withdrawal adjusted for inflation. If you took 4% of the current balance instead, your income would move with the market. The first approach protects your lifestyle but drains the portfolio faster. The second protects the portfolio but makes your income swing with the market.
Run it yourself: our free FIRE calculator lets you test scenarios with your own numbers, and our Social Security calculator shows how guaranteed income reduces how much you must pull from savings.
If you are still deciding on a savings target, our guide on how much you really need to retire helps you reconcile a withdrawal rate with your overall goal. For extra context on early retirement, the ExpressPlanner early retirement guide is a useful read.
Why does asset allocation change how safe your withdrawals are?
Sequence risk is easiest to see in a short example. Imagine two retirees who each start with the same illustrative portfolio value and withdrawal. One experiences a market drop early, while the other sees it later, after years of growth. The same average return can produce a very different result for the first retiree, because she had to sell low.
In the historical studies, higher equity exposure generally improved the odds that withdrawals would last, but it also meant bigger swings along the way. A portfolio that is too conservative can run short because it does not grow enough, while one that is too aggressive can force you to sell at bad moments.
Practical mitigations include:
A short-term buffer: hold some spending in cash or short bonds so you are not forced to sell stocks in a downturn.
Phased withdrawals: trim spending after a bad year and restore it when markets recover.
Partial annuitization: turn part of your savings into guaranteed lifetime income to cover essential bills.
Regular rebalancing: keep your mix on target. Our rebalancing schedule guide shows a simple routine.
For help choosing a mix, see our guide to asset allocation by age.
What are the alternatives when 4 percent looks risky?
If a fixed rule feels too rigid, several adaptations keep the spirit of the rule while letting you respond to markets.
Percent-of-portfolio: withdraw a set share of the current balance each year. Your income moves with the market, but you cannot run out of money outright.
Guardrails: set bands around your withdrawal. If the portfolio rises past the upper band, you give yourself a raise. If it falls past the lower band, you trim spending.
Performance-linked spending: tie discretionary spending to how the portfolio has done.
A lower starting rate: begin at 3% to 3.5% if you retire early or want more margin.
Cash or bond buffers and partial annuities: cover essentials with steadier income.
For readers who want more rigour, research on probability-of-failure decision rules argues that withdrawal safety is time-dependent. It suggests rule-based or dynamic approaches can capture retiree risk better than one fixed initial percentage.
Pro Tip: Decide your guardrail rules before retirement, while you are calm. Choosing under pressure in a downturn is when people make the costliest decisions.
How do you choose a withdrawal rate that fits you?
Work through these steps and write down your answers.
Identify your horizon. Subtract your retirement age from a realistic planning age, and lean longer if you are healthy or retiring early.
List guaranteed income. Count pensions and Social Security, plus Canadian benefits such as CPP and OAS if they apply to you. The more essential spending they cover, the less you need from the portfolio.
Set an acceptable failure probability. Decide how much risk of running short you can live with.
Choose your asset allocation. Match it to your horizon and your nerves.
Model scenarios. Test a strong market, a weak one, and a bad early stretch.
Set monitoring triggers. Bengen’s analysis suggests taking pre-emptive action when withdrawals rise 25% above the initial withdrawal rate.
Check your plan at least once a year, and again after any big market move or life change. If your numbers look tight, a financial planner or a scenario tool can help you test options before you commit.
Why numbers alone do not protect your retirement
We see the same pattern again and again: the maths is rarely what breaks a withdrawal plan, behaviour is. Early retirement feels like a victory lap, and spending runs ahead of the plan before anyone notices. A good withdrawal rate fails quietly if the spending habits behind it do not match. That is why we pair real-time coaching with personalized insights to help you stay on track. Plan the numbers, then build supports that keep you on them.
— Maanya
Test your withdrawal plan with Psyfiapp
We built tools to help you model the 4% rule and then stay disciplined with it:
Free US finance calculators for withdrawal and retirement scenarios
Personalized insights to help you stay on track
Account linking so your numbers reflect your real spending
Personalised nudges when spending drifts from your plan
Start with our free finance calculators, or explore Premium Monthly at 9.99 USD per month or Premium Annual at 69.99 USD per year to see whether your plan holds up.
This article is general information, not a substitute for advice from a qualified financial advisor. Consult a qualified financial professional about your own circumstances before acting on anything here.
FAQ
How long will my money last with the 4% rule?
In the historical data Bengen examined, a 4% first-year withdrawal with inflation adjustments generally lasted through 30-year windows. Your results depend on your asset mix, market returns and how long you actually need the money.
How much money do you need to retire with $100,000 a year income?
Divide your desired annual income by 0.04 to estimate the portfolio amount before counting guaranteed income. Pensions or Social Security reduce the amount you need to draw from savings.
Why is the 4% rule considered outdated?
Critics say it relies on past returns, assumes a fixed 30-year horizon, and ignores sequence risk and low bond yields. It can also be inefficient, leaving large balances unspent. Many planners prefer flexible rules or a lower starting rate.
Can you retire at 62 with $400,000?
Retiring early also means a potentially long horizon, so a lower starting rate and guaranteed income matter. Model your own numbers before deciding.
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This content is provided for general informational and educational purposes only and does not constitute financial, investment, tax, or legal advice. PsyFi provides financial coaching tools and behavioral insights, not regulated advisory services. Always consult with a qualified financial advisor or tax professional regarding your personal situation before making financial decisions.
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