401(k) Withdrawal Calculator – How Long Will Savings Last

Once you stop working, your 401(k) turns from a savings vehicle into a paycheck replacement. The challenge is simple to describe but hard to solve in practice: how much can you safely withdraw each year without running out of money too soon. This 401(k) withdrawal calculator estimates how long your current plan may last, how it compares with your goal age, and what first year withdrawal might better match that goal.

How the 401(k) withdrawal calculator works

The calculator models your 401(k) as a single retirement account that grows with investment returns and shrinks with annual withdrawals. You enter your current age, a goal age for how long you would like your 401(k) to last, your current 401(k) balance, the amount you plan to withdraw in the first year, your expected annual investment return and how fast you expect withdrawals to grow each year.

Behind the scenes, the tool runs a year by year projection. Each year your balance grows by the investment return you entered, then your withdrawal for that year is deducted. Withdrawals start at your chosen first year amount and then increase at the percentage you entered for annual increases, which many people use as a rough inflation assumption.

The calculator then measures how long it takes for the projected balance to reach zero, up to an internal cap of 80 years of withdrawals. If the account never hits zero within that window, the results show that your 401(k) is not projected to be fully depleted within that time frame.

The main metrics you see include:

• Estimated time before savings are depleted: the projected number of years your 401(k) can support your withdrawal plan before running out, based on your inputs.
• Approximate age when 401(k) may run out: your current age plus the projected number of years until depletion. If the calculator does not project depletion within 80 years, you will see that the account is not expected to run out within that period.
• Total withdrawals before depletion or goal age: the total amount you may withdraw from the account by your goal age, or until the account runs out, whichever comes first.
• Estimated balance at goal age: the remaining 401(k) balance at your goal age if the account is not depleted before then, or zero if the model projects that you will run out before your goal age.
• Suggested first year withdrawal for this goal: a back solved first year withdrawal that would, under your return and inflation assumptions, aim to reach your goal age with little or no balance left.

This structure is similar to many retirement withdrawal frameworks that model portfolio longevity using a constant real or inflation adjusted withdrawal. Research on the so called 4 percent rule, for example, examines whether a given initial withdrawal rate adjusted annually for inflation can last through a 30 year retirement across many market histories.

What your results mean for your retirement plan

When you adjust the inputs, the first thing to look at is how your plan compares to your goal. If the estimated time before savings are depleted is shorter than the number of years between your current age and your goal age, the calculator is telling you that your current withdrawal plan may draw down the 401(k) too quickly under the assumptions you entered.

For example, suppose you are 65 years old with a 401(k) balance of 900,000 dollars, you plan to withdraw 60,000 dollars in the first year, expect a 5 percent annual return and increase withdrawals by 2.5 percent per year. The calculator may show that your current plan lasts just under 20 years, taking you into your mid 80s. If your goal age for your savings is 95, the tool will highlight that your plan could run out earlier than your goal age.

The suggested first year withdrawal gives you a reference point for how much you could withdraw in the first year if you wanted your 401(k) to last to your goal age with little or no balance left. In the example above, that amount might be meaningfully lower than 60,000 dollars. If you can accept a smaller withdrawal, the model suggests your money is more likely to last to your goal age, assuming the return and inflation inputs prove realistic.

You can also compare the withdrawal rates as a quick check. A first year withdrawal of 60,000 dollars on a 900,000 dollar balance is a 6.7 percent initial withdrawal rate. Many planners treat starting withdrawal rates in the 3 to 5 percent range as more conservative for a long retirement horizon, especially when expected returns are modest and inflation risk is present. Recent research suggests that a 4 percent initial withdrawal rate may not be safe in all market environments, particularly when bond yields are low and inflation is higher.

At the same time, if your plan already lasts at least to your goal age, the suggested first year withdrawal may be higher than you currently plan to take. That does not mean you should immediately increase your spending, but it does show that, under the calculator assumptions, you may have room to raise withdrawals while still targeting your goal age.

These comparisons help you see tradeoffs. Higher withdrawals feel better today but increase the risk of outliving your savings, while lower withdrawals give your portfolio more room to handle market downturns and inflation over a long retirement.

Ways to adjust if your 401(k) runs out too early in the projection

If the calculator shows that your withdrawals are likely to deplete your 401(k) before your goal age, you have several levers you can consider. The right mix depends on your broader financial picture, including Social Security, pensions, taxable investments, annuities, home equity and whether you plan to work part time.

First, you can reduce your planned withdrawal amount, either immediately or by making smaller inflation increases over time. Dropping your first year withdrawal from 60,000 dollars to 50,000 dollars and holding inflation increases at 2 percent instead of 3 percent can significantly extend the life of your portfolio in the model.

Second, you can adjust your goal age or retirement timing. If working even one or two more years is realistic, that can give your 401(k) more time to grow and reduce the number of years you need it to support withdrawals. Delaying Social Security benefits can also increase your guaranteed income later, which may let you rely less heavily on your 401(k) each year.

Third, you can revisit your investment mix. A portfolio that is too conservative may not grow fast enough to support your withdrawals, while one that is too aggressive may expose you to sharp losses that are hard to recover from once you start drawing income. Many providers publish model asset allocations for retirees and near retirees based on risk tolerance and time horizon, and a financial professional can help tailor this to your specific situation.

Finally, you can look at ways to smooth your withdrawals across different accounts and income sources. Some retirees use a higher 401(k) withdrawal rate in their early years while deferring Social Security benefits, then lower their 401(k) withdrawals once higher Social Security checks begin. Others build a small cash buffer or short term bond ladder to cover several years of expenses, reducing the need to sell investments after market declines.

Limitations of the calculator and when to get help

Like any retirement model, this calculator simplifies reality. It uses a single average return each year and a steady withdrawal pattern. Actual markets move unpredictably, and the order of returns can matter as much as the average return. A string of poor returns in the early years of retirement can reduce portfolio longevity even if later returns are strong, a risk often called sequence of returns risk.

The tool also looks only at one 401(k) account at a time and does not include the impact of required minimum distributions, taxes, Roth conversions, different account types, or changes in spending over time. In practice, many retirees do not increase their spending every year by inflation, and real world budgets can go up or down with health, travel plans and other life events.

For these reasons, you should treat the results as a starting point for conversations and planning rather than a precise forecast. If you are within ten years of retirement or already retired, it can be helpful to review your plan with a qualified financial planner or advisor who understands your full situation, including taxes, estate plans and healthcare costs.

Used thoughtfully, however, this 401(k) withdrawal calculator can help you see how sensitive your plan is to different withdrawal amounts, returns and inflation assumptions. Small changes to any of these inputs can meaningfully affect how long your savings may last, and that awareness is a key step toward building a retirement plan that feels both sustainable and flexible.