Finance · 5 min read

How Much Do I Need to Retire? The 4% Rule Explained

Written by Muhammad Ajmal · Last reviewed 2026-08-19

The simplest way to answer "how much do I need to retire" is to multiply your expected annual spending by 25. That comes from the 4% rule, a widely used guideline for how much you can safely withdraw from savings each year without running out of money over a typical retirement. Run your own numbers through our retirement calculator to see how contributions and time affect that target, then use the math below to check the result.

Where the 4% rule comes from

The rule traces back to research by financial planner William Bengen in the 1990s, later expanded by a group of professors at Trinity University in what became known as the Trinity study. Both looked at historical US stock and bond returns and asked a specific question: if a retiree withdrew a fixed percentage of their portfolio in year one, then adjusted that dollar amount for inflation every year after, what withdrawal rate would have survived the worst 30-year stretches in the historical data without the portfolio hitting zero? The answer that held up across most historical periods was close to 4%.

The 25x shortcut

If 4% of your savings should cover one year of spending, your full savings target is your annual spending divided by 0.04, which is the same as multiplying by 25. Someone who expects to spend $40,000 a year in retirement would target $1,000,000 saved. Someone spending $60,000 a year would target $1,500,000. The 25x figure is just the 4% rule written the other way around, and it is the version most people find easier to hold in their head while checking progress.

A worked example

• Annual retirement spending goal: $50,000
• Target portfolio (25x): $1,250,000
• Year-one withdrawal (4%): $50,000
• Year-two withdrawal, assuming 3% inflation: $51,500

The withdrawal amount rises with inflation each year regardless of how the portfolio performed, which is what makes the rule simple to apply but also what creates its biggest weakness.

What the rule assumes

The 4% figure was built around a specific portfolio, roughly 50 to 75% stocks and the rest bonds, held over a 30-year retirement. It assumes withdrawals rise with inflation on a fixed schedule regardless of market conditions, and it does not account for taxes, since a taxable brokerage account, a traditional IRA and a Roth IRA all produce different after-tax income from the same withdrawal amount.

Where it can break down

A retirement that starts right before a market downturn is in a worse position than one that starts right before a rally, even if both portfolios average the same return over 30 years. This is called sequence of returns risk, and it is a bigger factor than the average return itself. Withdrawing a fixed, inflation-adjusted amount from a portfolio that has just dropped 30% locks in losses that a more flexible approach could avoid. Retirements longer than 30 years, early retirement being the common cause, also call for a more conservative rate, since the original research was not built to stretch that far.

A more flexible approach

Many retirees do not spend a flat inflation-adjusted amount every single year in practice. Spending often runs higher in the early years of retirement, eases off in the middle years, and can climb again later as healthcare costs increase with age. Some planners suggest skipping the inflation increase in years that follow a market decline, which lowers the odds of running out of money without permanently cutting your lifestyle. The 4% rule works well as a starting point for that conversation. It was never meant to be followed mechanically for three decades straight.

Using it alongside your own numbers

Multiplying spending by 25 gives you a target to work toward, but how you get there, through contributions, employer matching and years of growth, is where the real planning happens. Enter your current savings, monthly contribution and timeline into the retirement calculator to see whether your current pace lines up with your 25x number, and adjust your contribution rate if there is a gap.

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