Retirement Calculator — 401k & FIRE

The most widely used benchmark is 25× annual expenses — a target built on the Trinity Study's 4% safe withdrawal rate over a 30-year horizon. A household spending $60,000 per year in retirement needs roughly $1.5 million invested; spending $80,000 needs $2 million; spending $100,000 needs $2.5 million. These targets assume Social Security replaces a separate portion of income — typically 30-40% for median earners, less for high earners.

Age-based milestones from Vanguard and Fidelity research: at age 30, roughly 1× annual salary saved; at 40, 3×; at 50, 6×; at 60, 8×; at 67 (full retirement age), 10×. These are median-investor benchmarks — earlier savers, higher savers, and FIRE (Financial Independence / Retire Early) targets all diverge upward.

Contribution rate is the primary driver. The 2026 IRS 401(k) employee contribution limit is $23,500 ($31,000 age 50+ with catch-up). IRAs cap at $7,000 ($8,000 age 50+). Employer match is free money that effectively raises the contribution rate — capturing the full match (typically 3-6% of salary) is the minimum baseline.

Time horizon compounds the effect. A $10,000 annual contribution starting at age 25 grows to roughly $1.5 million by age 65 at a 7% real return; starting at age 35 reaches only $740,000; starting at 45 reaches $340,000. Asset allocation matters less than contribution rate and time — a target-date fund at the appropriate retirement year provides age-appropriate risk without manual rebalancing. Fees compound in reverse: a 1% expense ratio reduces a 40-year balance by roughly 20%.

Social Security benefits are calculated from the 35 highest-earning years, indexed to wage growth. Full retirement age is 67 for everyone born 1960 or later. Claiming early at age 62 reduces the monthly benefit by roughly 30%; claiming late at age 70 increases it by 24% (to 32% depending on birth year). The break-even age for delayed claiming is approximately 80-82 — claimants expecting to live past 80 typically gain lifetime income by waiting.

Maximum 2026 monthly benefit at full retirement age is approximately $4,018; maximum at age 70 is approximately $5,108. Average retired worker benefit in 2026 is roughly $1,900 per month. Social Security is partially taxable: up to 50% of benefits are federally taxable if combined income exceeds $25,000 single / $32,000 married, and up to 85% above $34,000 single / $44,000 married. Twelve states still tax Social Security in 2026; the rest do not.