401k Calculator

The 401(k) calculator projects a retirement account balance from a starting age to a planned retirement age, then converts that balance into a retirement income figure. Age, current salary, existing 401(k) balance, and contribution rate anchor the projection, and because the contribution rate applies to a salary that grows every year, the dollar amount contributed rises over time even at a fixed percentage. Employer match and match limit set how much of that growth comes from company money rather than personal deposits, and life expectancy sets how long the final balance has to last. Investment return and inflation rate together separate the nominal projection from what the balance is actually worth in today's dollars.

The projection runs as a yearly schedule and a stacked chart that track employee contributions, employer match, and investment growth separately, alongside a final balance figure. Purchasing power restates that final balance in today's dollars using the inflation rate, so a large nominal figure can still represent a smaller real one. Three withdrawal models turn the final balance into retirement income: a fixed purchasing power monthly income that holds its real value across retirement, a fixed monthly amount that does not adjust for inflation, and a fixed annual amount.

The model compounds annually: each year adds employee contributions, employer match, and investment growth to the running balance until retirement. Salary rises every year by the chosen growth rate, and the contribution percentage applies to that updated, higher salary, so later years contribute more in dollar terms even at a constant contribution rate. The annual return then compounds on top of the growing balance to represent market growth over the full working period.

Results appear in both future value and inflation-adjusted terms, since a large nominal balance decades away buys less than the same number today. At retirement, standard time-value-of-money formulas convert the final balance into three withdrawal scenarios: a fixed purchasing power monthly income that stays level in real terms, a fixed monthly amount, and a fixed annual amount, each sized to remain payable across the chosen retirement horizon.

• Plan contributions by testing different employee contribution rates and employer match structures.
• Compare retirement ages to see how additional working years change the final balance and income.
• Test market assumptions by adjusting investment return and inflation to assess sensitivity.
• Set income targets by modeling monthly or annual withdrawals against a retirement budget.
• Present a savings strategy to a partner or advisor using the yearly schedule, chart, and purchasing power figures as supporting detail.

The final balance is the gross amount projected to be available at retirement, before taxes. Purchasing power restates that figure in today's dollars using the inflation rate, so it reflects real buying power rather than a nominal total. The contribution summary separates employee deposits, employer match, and investment returns, showing how much of the balance came from each source. The yearly schedule shows how a change to any single input, such as contribution rate or return, compounds differently depending on how many years remain until retirement.

Raising the contribution rate from 8 percent to 12 percent increases both the final balance and the monthly income it can support. Raising the annual return from 5 percent to 7 percent shows how much compounding accelerates growth over a long horizon. Shifting retirement age from 62 to 67 estimates the benefit of five more years of contributions and market growth. Lowering inflation from 3 percent to 2 percent shows how price changes affect real purchasing power for the same nominal balance.

Does this calculator include IRS contribution limits? No, the calculator uses the contribution percentages entered by the user. Check the current IRS contribution limits for 401(k) plans and keep inputs within the legal limits.

How realistic are the investment return assumptions? Investment returns vary significantly over time. The calculator applies a constant average return, but actual results may differ. Conservative estimates tested across several scenarios give a more realistic range of outcomes.

Can I include Roth 401(k) contributions? The calculator models pretax contributions and growth. It can still estimate balances for Roth accounts, but Roth withdrawals are tax-free under qualified conditions, which this projection does not distinguish. A financial advisor can compare Roth and traditional strategies in more detail.

What happens if my employer changes the match policy? Updating the employer match percentage and limit and recalculating shows the effect of a different policy on long-term retirement savings.

Does the tool account for taxes during retirement? No, the calculator shows gross balances and withdrawals before taxes. Actual income may be lower depending on tax rates in retirement, so the results serve as a planning baseline rather than a net figure.

How should I set my inflation rate? Long-term averages or personal expectations both work as a basis; 2 to 3 percent is a commonly used planning range, and testing more than one rate shows how sensitive the projection is to cost-of-living assumptions.

Can I use this for other retirement accounts like IRAs? Yes, the same principles apply to IRAs, SEP IRAs, and other defined contribution accounts. Setting employer match inputs to zero models accounts that do not offer matching contributions.

What if I retire earlier or later than planned? Changing the retirement age shows how retiring earlier reduces compounding and retiring later increases both contributions and growth. The projection recalculates immediately for the new age.

How often should I update my inputs? At least once a year, or whenever salary, contribution rate, or investment strategy changes. Regular updates keep the projection aligned with current financial circumstances.