Question 1

How long will my 401k last?

Accepted Answer

It lasts until your withdrawals, rising with inflation, outpace what the balance earns and drain it to zero. A $750,000 pot earning 5% a year with $4,000 monthly withdrawals that rise 3% annually lasts about 27 years — to roughly age 92 if you start at 65. Lower withdrawals or higher returns extend it, sometimes indefinitely if you withdraw less than the balance earns; higher withdrawals shrink it faster each year as inflation lifts the amount you take. That $4,000-a-month example is about a 6.4% first-year withdrawal rate, well above the traditional 4% guideline. One caveat: this assumes a steady average return, so a poor sequence of returns early in retirement can drain the balance faster, and it ignores taxes, Social Security, and the required minimum distributions that begin at age 73.

Question 2

How much will my 401k pay me per month?

Accepted Answer

A common starting point is the 4% rule: withdraw 4% of the balance in the first year, then raise the dollar amount with inflation each year after. On a $750,000 balance that is $30,000 in year one, or about $2,500 a month, designed to last around 30 years. A more conservative 3% would draw $22,500 a year (about $1,875 a month) for extra safety, while a 5% rate lifts income to about $3,125 a month but raises the risk of running short. Your sustainable income depends on your balance, expected return, inflation, and how long the money must last. One caveat: these are pre-tax figures — traditional 401k withdrawals are taxed as ordinary income — and a market downturn in your early retirement years does far more damage than the same drop later, because you sell assets to fund withdrawals.

Question 3

How to calculate 401k payout?

Accepted Answer

For a quick estimate, multiply the balance by a sustainable withdrawal rate — often 4% — to get the annual payout, then divide by 12 for the monthly figure. On $600,000, 4% is $24,000 a year, or about $2,000 a month in the first year, rising with inflation thereafter. For a more accurate answer, simulate it month by month: grow the balance by the monthly return, subtract the withdrawal, and increase the withdrawal each year for inflation — which is what this calculator does. The result shows both your monthly income and how many years the balance lasts. One caveat: the payout is pre-tax for a traditional 401k, so your spendable income is lower after ordinary income tax, and required minimum distributions from age 73 can force withdrawals larger than a fixed-rate plan assumes.

Question 4

How to calculate how long your 401k will last?

Accepted Answer

Simulate the balance month by month: multiply it by the monthly return (annual return ÷ 12), subtract that month's withdrawal, and raise the withdrawal once a year for inflation. The number of months until the balance reaches zero, divided by 12, is how long it lasts. For example, $500,000 earning 5% with $3,000 monthly withdrawals rising 3% a year lasts roughly 18 years; cutting the withdrawal to $2,500 stretches it well beyond 25. If withdrawals stay below what the balance earns, it can last indefinitely. This calculator runs that simulation for you and reports the exact year the money runs out. One caveat: it uses a steady average return, so real-world volatility — especially a downturn early in retirement — can shorten the horizon, and it excludes taxes and required minimum distributions from age 73.

Question 5

What is a safe withdrawal rate for a 401k?

Accepted Answer

The traditional benchmark is the 4% rule: withdraw 4% of your starting balance in the first year, then adjust that dollar amount for inflation annually, aiming to make the money last about 30 years. On $750,000 that is $30,000 in the first year. More cautious retirees use 3% to 3.5% for a longer horizon or greater certainty, while a shorter retirement can support a higher rate. The right figure depends on your time horizon, expected returns, and how much flexibility you have to cut spending in bad years. One caveat: the 4% rule came from historical U.S. market data and is a guideline, not a guarantee — sequence-of-returns risk means a market drop in your first few retirement years is far more dangerous than a later one, and the rule ignores taxes and required minimum distributions from age 73.

How Long Will My 401k Last Calculator