Retirement Calculator 2026: 401(k), IRA, Roth + SECURE 2.0

The compounding asymmetry. A dollar contributed at age 25 has 40 years to compound; a dollar contributed at age 55 has 10. At a 7% nominal return, those dollars become $14.97 and $1.97 respectively — the early dollar is 7.6× more valuable. This is why every retirement framework starts with the same advice: capture employer match first, max contributions second, optimize tax structure third. The order isn't arbitrary. A 100% match on a 4% contribution is an instant 100% return; no investment strategy beats free money. The simulator lets you see exactly how much match you're leaving on the table — captured by running the live employer-match formulas against your inputs.

Pre-tax vs Roth: the bracket-arbitrage question. When you contribute to a Traditional 401(k), you skip federal/state income tax now and pay it at withdrawal. When you contribute to Roth, you pay tax now and skip it forever (qualified distributions). The decision reduces to one comparison: is your current marginal tax rate higher or lower than the rate you'll face in retirement? If meaningfully higher today (say, 32% now vs 22% in retirement), Traditional wins — you save 32¢ on every dollar deferred and only pay 22¢ later. If meaningfully lower today (22% now vs 32% in retirement, common for people early in their careers expecting promotions), Roth wins. When the rates are close, splitting contributions hedges against tax-rate uncertainty and provides flexibility around RMDs (which we'll get to).

Employer match patterns and vesting. Real-world employer match comes in four common patterns. The simplest is dollar-for-dollar match up to a cap (commonly 4% or 5% of salary). The most common is the Safe Harbor tiered structure: 100% on the first 3% of salary plus 50% on the next 2%, capping at an effective 4% match when the employee contributes 5% or more. A third pattern is straightforward 100% match up to 5% (more generous, used to attract talent in competitive industries). The fourth is custom — typically used by larger employers with profit-sharing components. The calculator implements all four; for custom, you can specify your own tier structure. Vesting matters because the employer match is technically conditional: cliff vesting (0% for 3 years, then 100%) and graded vesting (20% per year starting year 2, fully vested after 6) are both legal under ERISA. If you're 2 years into a cliff schedule, you have $0 of vested employer match — the entire balance forfeits if you leave. The calculator shows you the unvested figure so you can decide whether staying long enough to vest is worth the trade-off against a job change.

The 4% rule and its limits. William Bengen's 1994 paper found that a 50/50 stock-bond portfolio could sustain 4% annual withdrawals (inflation-adjusted) for 30 years across every historical sequence in US data. The rule was never meant as a guarantee — it was the worst-case-survivable rate from the 1968 retiree's perspective (the worst case in his data set). Modern critiques focus on three weaknesses: it doesn't account for sequence-of-returns risk in early retirement (a 30% drop in year 1 is much worse than the same drop in year 25), it assumes US-equity-heavy portfolios will continue producing 7% real returns (forward-looking estimates from Vanguard, BlackRock, and Research Affiliates as of 2026 are 4.5-6% real), and it ignores healthcare cost inflation that runs 1-2% above general inflation. Bengen himself updated to 4.5% with a more diversified portfolio in his 2006 follow-up. Conservative practitioners now use 3.3-3.5% with guardrails, or dynamic withdrawal strategies that flex spending based on portfolio performance. The calculator uses the original 4% as a baseline so the editorial example numbers track historical convention, but treats sustainability as a binary check (does the portfolio survive to your stated life expectancy?) rather than a precise income guarantee.

RMDs at age 73 and the Roth conversion strategy. Required Minimum Distributions kick in at age 73 (raised from 72 by SECURE 2.0 §107, scheduled to rise again to 75 in 2033). The first RMD is roughly 3.77% of the prior year-end balance (using the IRS Uniform Lifetime Table divisor of 26.5). On a $1,000,000 traditional balance, that's $37,736 of forced taxable income — whether you need it or not. Two consequences: you may be pushed into a higher tax bracket precisely when you have less control over income, and Social Security benefits become taxable at lower phase-out thresholds when combined with RMD income. The defensive strategy is partial Roth conversions in lower-income years (early retirement before Social Security claim, sabbaticals, gap years) — pay tax voluntarily at a lower rate today to reduce the RMD-forced taxable income later. Roth IRAs have no lifetime RMD for the original owner, and Roth 401(k) RMDs were eliminated entirely starting 2024 (SECURE 2.0 §325). This is part of why high earners often skew Roth even when current-vs-retirement bracket math suggests Traditional.

IRA phase-outs are sneakier than they look. The Roth IRA contribution phase-out starts at $153,000 for single filers and $242,000 for MFJ in 2026, ending at $168,000 and $252,000 respectively. Within the range, contribution capacity phases down linearly. Above the upper bound, direct Roth IRA is closed (though backdoor Roth via non-deductible Traditional contribution + immediate conversion remains a strategy for those with no pre-tax IRA balance — the calculator doesn't model it because the implementation depends on factors outside the contribution decision). Traditional IRA deductibility has its own three-flavor phase-out: filer covered by workplace plan ($81-91k single, $129-149k MFJ), filer not covered but spouse covered ($242-252k MFJ-only special range), or neither covered (fully deductible regardless of income). The calculator assumes you're covered if you have any 401(k) activity, which catches most working filers correctly.