Retirement / 401(k) Calculator

How it works

A retirement calculator helps you answer the most important financial question most people face: will I have enough to retire? It works by compounding your current savings forward at an assumed rate, while adding your annual contributions and any employer match. The result is an estimated balance at retirement age and an estimated annual income using the well-known "4% safe withdrawal rule".

The 4% rule, originally derived from the Trinity Study, suggests that a retiree can withdraw 4% of their portfolio in the first year and adjust that amount for inflation each subsequent year, with very high probability of the portfolio lasting 30 years. It is a guideline, not a guarantee — modern researchers debate whether 3.5% or 4.5% is more appropriate depending on market conditions and retirement length — but it is a reasonable starting point for planning.

The biggest lever in retirement planning is your savings rate. Maximizing your employer match is essentially free money: if your company matches 100% of the first 4% you contribute, that 4% match is an instant 100% return on those dollars. Beyond the match, financial planners often recommend saving 10–20% of gross income for retirement, depending on your starting age and goals.

Time also dominates: starting at 25 vs. 35 with the same contribution can roughly double your retirement balance because the early dollars compound for the longest. Even small differences in expected return have outsized effects: a 7% vs. 6% return over 35 years adds nearly 50% to the final balance.

This calculator does not model taxes, Social Security, or sequence-of-returns risk. For comprehensive planning, talk to a fee-only fiduciary advisor and stress-test your plan with Monte Carlo simulation.