How Much Do You Need to Retire? The 25x Rule and Its Limits

"How much do I need to retire?" has no single answer, but it has a reliable method: estimate your spending, subtract income you can count on, and work out how large a portfolio is needed to fill the gap. This guide walks through the most widely used shortcut, the 25x rule, explains where it falls short, and shows how government pensions change the picture in different countries.

Step 1: Estimate your retirement spending

The key number is not your salary but what you will spend each year in retirement. Some costs typically fall, such as commuting. Others often rise, including healthcare and travel in early retirement.

Rules of thumb such as needing 70% to 80% of pre-retirement income exist, but building the estimate from your own expenses is usually more accurate.

Step 2: Subtract guaranteed income

Next, subtract income that does not depend on investment performance, such as government pensions, defined-benefit pensions or annuities. What remains is the gap your savings must cover.

Step 3: Apply the 25x rule

Multiply that annual gap by 25. This gives a portfolio from which you could withdraw 4% in year one, then adjust that amount for inflation each year.

The two ideas are the same calculation viewed from opposite directions: 25 × annual spending = portfolio target, and 4% × portfolio = first-year withdrawal.

Worked example

Imagine a couple who expect to spend 60,000 a year in retirement, in today's money. They estimate that government pensions will provide a combined 18,000 a year.

• Annual gap: 60,000 − 18,000 = 42,000
• Target at a 4% withdrawal rate: 42,000 × 25 = 1,050,000

Here is how the target changes with more conservative withdrawal rates:

The withdrawal rate moves the target by hundreds of thousands, which is why the rule's assumptions matter.

The caveats behind the 4% rule

It comes from US historical data

The 4% guideline grew out of research published in the 1990s, most notably by financial planner William Bengen and a later study by professors at Trinity University. They examined how portfolios of US stocks and bonds would have performed over rolling 30-year periods. The US had one of the strongest stock markets of the twentieth century, and studies using data from other countries have often found lower historically safe withdrawal rates. Past results are not a promise about the future.

Sequence-of-returns risk

The order of returns matters greatly once you are withdrawing money. A large market fall early in retirement forces you to sell more investments at low prices, leaving less to recover, so two retirees with the same average return can have very different outcomes. Common defences include a cash or bond buffer and spending less after poor years.

Longevity

The original research focused on 30-year retirements. Someone retiring at 45 might need their money to last 50 years or more, and longer horizons generally call for a lower withdrawal rate.

Fees, taxes and flexibility

The research largely ignored investment fees, and many withdrawals are taxable. On the other hand, flexible spending, such as skipping inflation increases after a bad year, can meaningfully improve the odds of success.

FIRE variants

FIRE (Financial Independence, Retire Early) uses the same 25x arithmetic, often with a lower withdrawal rate because early retirements can be very long.

Coast FIRE example

Suppose someone aged 40 wants the 1,050,000 target from the earlier example by age 65, measured in today's money. If their portfolio grows at an assumed 5% a year after inflation, they would need roughly 310,000 invested today and could then stop contributing. At an assumed 4% real return, the figure rises to roughly 394,000. These are illustrations only.

Barista FIRE example

If the same couple earned 20,000 a year from part-time work, their gap would fall from 42,000 to 22,000. At 25x, the portfolio needed falls from 1,050,000 to 550,000.

Government pensions vary by country

Government pensions can cover a large share of basic spending, so check your projected entitlement with the relevant agency. Rules and ages change over time.

United States

Social Security benefits are based on your highest 35 years of indexed earnings. You can claim from 62 at a reduced rate; full retirement age is 67 for people born in 1960 or later, and delaying up to 70 increases the monthly benefit.

Canada

The Canada Pension Plan (CPP), or the Quebec Pension Plan in Quebec, is based on contributions from employment. It can start between 60 and 70, with 65 as the standard age. Old Age Security (OAS) is based mainly on years of residence, typically starts at 65 and is partly recovered from higher-income recipients.

United Kingdom

The new State Pension depends on your National Insurance record. A full pension typically requires 35 qualifying years, with at least 10 needed to receive anything. State Pension age is rising from 66 to 67 between 2026 and 2028, with further increases planned later.

India

There is no universal state pension for most private-sector workers. Salaried employees in covered workplaces typically build savings through the Employees' Provident Fund (EPF), and part of the employer contribution goes to the Employees' Pension Scheme, which pays a modest monthly pension. The National Pension System (NPS) is open to most citizens, and part of the corpus is typically used to buy an annuity at retirement.

Australia

Compulsory employer superannuation contributions build most people's retirement savings, and super can generally be accessed once you reach preservation age, which is 60, and retire. The Age Pension, available from 67, is means-tested on both income and assets, so many retirees receive a part pension alongside their super.

Common mistakes to avoid

• Basing your target on current income instead of expected spending.
• Treating the 4% rule as a guarantee rather than a historical guideline.
• Assuming a government pension amount without checking your official record.
• Planning for a 30-year retirement when yours could last much longer.

Watch: a visual explainer

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Video by Ben Felix, embedded via YouTube. Private.Finance is not affiliated with the creator.

Frequently asked questions