How to Retire in 15 Years: Calculator + FIRE Roadmap

A 15-year FIRE plan is where serious accumulation meets the final optimization phase. You likely have real money already working for you — $200,000 to $750,000 saved — and compound growth is providing meaningful tailwind. Unlike the 5- or 10-year sprint where you're trying to close a large gap quickly, the 15-year plan is where many savers discover they've already hit Coast FIRE: their current portfolio will compound to their FI number on its own with zero additional contributions.

For most 15-year planners — typically 40 to 50 years old targeting retirement at 55 to 65 — Rule of 55 is the dominant bridge strategy. If you separate from your employer in the calendar year you turn 55 or later, you can draw any amount from your current employer's 401(k) without the 10% penalty, with no fixed schedule and no multi-year commitment. This makes the 15-year plan far simpler from an access perspective than earlier retirement targets.

Retire in 15 Years: Calculator

Enter your situation. The calculator shows your FI number for your specific retirement age and horizon, whether your current trajectory closes the gap in 15 years, and whether your existing portfolio has already reached Coast FIRE.

The 15-year FIRE equation

A 15-year plan sits between the full compounding power of the 20-year marathon and the sprint urgency of the 10-year plan. At 5% real return over 15 years, your money grows 2.08×. That means your starting balance matters considerably — a $500,000 portfolio at 5% real produces $1,039,500 in 15 years, covering more than half a typical FI number before you contribute another dollar. But ongoing contributions still dominate for savers starting below $500K.

The key insight for 15-year planners: many of you are already at Coast FIRE and don't know it. A 42-year-old targeting a $1,867,000 FI number (retiring at 57 on $70K/yr at 3.75% SWR) needs only $898,000 today at 5% real to be fully coasted. A dual-income household in their early 40s who has been maxing 401(k)s and IRAs for 12+ years may already be there.

Required annual savings: starting portfolio × real return (for $70,000/yr retirement spending)

The table below assumes $70,000/yr spending at a 3.75% SWR (35-year horizon — a 42-year-old retiring at 57) = $1,866,667 FI number. Adjust with the calculator above for your own spending.

FI number = $70,000 / 3.75% = $1,866,667. FV formula: FV = PV×(1+r)¹⁵ + PMT×((1+r)¹⁵−1)/r. "On track" means projected FV exceeds FI number with $0 additional savings (Coast FIRE). Adjust in calculator above for your spending and SWR.

At 7% real return, $750K is already coasted — every dollar added is pure buffer. At 5% real, the coast threshold is about $900K. If you're between $400K and $750K with 15 years left, you're in the final push — and likely need only modest incremental savings to close the gap.

The Rule of 55: your 15-year plan's best tool

Most 15-year planners are in their 40s targeting retirement at 55 to 60. If you separate from your employer in the calendar year you turn 55 or later, you can withdraw any amount from that employer's 401(k) penalty-free. No 10% early distribution. No fixed schedule. No multi-year commitment. ¹

This makes the 15-year plan fundamentally simpler than earlier retirement scenarios. Your pre-59½ access strategy:

1. Build your 401(k) aggressively over 15 years — it's your primary Rule-of-55 asset.
2. Do NOT roll the 401(k) to an IRA before taking all the Rule-of-55 distributions you need. Rolling permanently eliminates the exception. This is the single most expensive mistake in a Rule-of-55 plan.
3. Use Rule of 55 draws for the bridge to 59½ (typically 0.5 to 4.5 years if you retire at 55–59).
4. Supplement with taxable brokerage and seasoned Roth conversion draws as needed.

Coast FIRE: most 15-year planners are closer than they think

Coast FIRE means your current portfolio will compound to your FI number on its own — you no longer need to save new money, though continuing builds a buffer or accelerates your timeline.

For a 42-year-old targeting a $1,867,000 FI number by age 57:

• At 5% real return, the coast threshold today is $1,867,000 / 2.079 = $898,000
• At 6% real return: $1,867,000 / 2.397 = $779,000
• At 7% real return: $1,867,000 / 2.759 = $677,000

A diligent dual-income household in their early 40s who has been maxing 401(k)s and IRAs for 12–15 years may have $700,000–$900,000 already — right at the coast threshold. Use the calculator above. If the Coast FIRE flag appears, you have options you may not have known existed: reduce savings, take a lower-stress role, fund a sabbatical, or simply keep saving and retire 3–5 years earlier than 15 years out.

See the Coast FIRE calculator for a dedicated model showing the exact coast threshold at different return assumptions.

Building tax-advantaged accounts: the 15-year math

At 6% real return over 15 years, $1 grows to $2.40. Max out every tax-advantaged vehicle in this order:

1. 401(k)/403(b) to employer match: Free money first. In 2026: $24,500 basic; $32,500 at ages 50–59; $35,750 at ages 60–63 (SECURE 2.0 super catch-up). ²
2. HSA to limit (if on HDHP): $4,400 self-only / $8,750 family in 2026. Triple tax advantage — deductible going in, tax-free growth, tax-free medical draws. HSA strategy guide. ³
3. Backdoor Roth IRA: If income exceeds the Roth phase-out ($153K–$168K single / $242K–$252K MFJ in 2026), use the backdoor Roth: $7,500/yr under 50, $8,600/yr at 50+. Backdoor Roth guide. ²
4. 401(k) to limit: Max out above the match.
5. Mega backdoor Roth (if plan allows): An additional $37,500+ annually into Roth via after-tax 401(k) contributions. Mega backdoor Roth guide.
6. Taxable brokerage: Your pre-59½ bridge (especially for retiring before 55) and LTCG harvesting platform. Taxable brokerage guide.

The Roth conversion ladder: start Year 1, not Year 13

If you plan to retire before 59½, each Roth conversion requires a 5-year seasoning clock before you can draw it penalty-free. A 42-year-old starting a 15-year plan who begins converting $20,000/yr in 2026 gets penalty-free draws from those conversions starting in 2031 — well before retirement at 57. This eliminates any need for a SEPP commitment and gives you a tax-efficient secondary draw alongside Rule of 55.

Don't wait until year 13 of your plan to start converting. A 42-year-old who starts at age 54 has no seasoned Roth conversions available when they retire at 57. Start now, even with small tranches, and let the clocks run in parallel with accumulation. Roth conversion ladder calculator.

Pre-59½ access by retirement age

Healthcare: a 7–10 year bridge

Retiring at 55–58 means a 7–10 year bridge before Medicare at 65. Three key points: ⁴

• Below the ACA cliff ($63,840 single / $86,640 MFJ in 2026): Subsidized marketplace coverage is available. The challenge is that Roth conversions and LTCG harvesting both count toward MAGI and can push you over the cliff — coordinate them carefully.
• Above the cliff: Budget $12,000–$20,000+/yr in unsubsidized premiums for a 55–60-year-old. Managing income via Roth sourcing and tax-loss offsetting can dramatically reduce this cost.
• COBRA transition: Leaving an employer mid-year? COBRA covers 18 months at 102% of the group premium — often cheaper than ACA until marketplace enrollment. Full healthcare guide.

Tax sequencing in a 15-year retirement

Traditional vs Roth during accumulation

If your current marginal rate is 22–24% and you plan to retire on $60K–$90K/yr (likely in the 10–12% bracket or lower), pre-tax 401(k) contributions during the 15-year accumulation phase beat Roth contributions. You defer tax at 22%+ now and pay at 10–12% in retirement — a spread that compounds over time. Roth vs traditional break-even calculator. ⁵

The Roth conversion golden window

Once retired and before Social Security begins, your taxable income may be very low. The 12% federal bracket tops out at $50,400 single / $100,800 MFJ in 2026. That window — between retirement and when SS and RMDs begin — is your best opportunity to convert traditional IRA balances to Roth at the lowest marginal rate you'll see. The 15-year planner who retires at 57 has a 16-year conversion window before RMDs at 73. Start converting in year 1 of retirement. Withdrawal order and four-constraint framework. ⁵

Social Security: the 15-year planner's zero-earnings impact

Social Security benefits are computed from your 35 highest-earning years. A 42-year-old who retires at 57 has worked roughly 20 years, leaving 15 zero-earning years in the 35-year calculation. Each zero-earning year reduces your eventual SS benefit by roughly 1/35th of what a full high-earning year would contribute to your AIME. For most 15-year planners, this reduces the eventual full-retirement-age benefit by 15–25% versus working to 67.

The practical approach: model SS as a bonus, not as part of your FI number. If it shows up, it reduces sequence-of-returns pressure or extends portfolio longevity — it's upside, not a dependency. The SS timing guide has a zero-earnings impact table and break-even analysis for claiming at 62 vs 67 vs 70.

15-year FIRE milestones

15-year FIRE mistakes to avoid

• Rolling the 401(k) to an IRA at separation. If you retire at 55–58 and roll the 401(k) to an IRA first, you permanently lose Rule-of-55 access. Leave it in the plan until you've drawn everything you need. Rule of 55 guide.
• Not starting Roth conversions in Year 1. A 42-year-old who waits until age 54 to start converting has no penalty-free Roth tranche available at retirement at 57. Start now, even with small amounts. Roth ladder calculator.
• Underestimating the ACA MAGI challenge. Roth conversions and LTCG harvesting both count toward MAGI. A plan assuming $60K/yr spending is below the ACA cliff can blow past it with $15K of annual Roth conversions. Model MAGI, not just spending. Healthcare before 65.
• Using a 30-year SWR for a 35–40 year retirement. Retiring at 55 with a 4.0% SWR (correct for 30 years) underfunds a 40-year plan by ~14%. Use 3.5% for 40yr, 3.75% for 35yr. SWR calculator.
• The calendar-year Rule-of-55 timing trap. Rule of 55 requires you to separate from the employer in the calendar year you turn 55 or later. Separating in December of the year you turn 54 means you must wait until next January, or age 55 by year-end, for the exception to apply. Plan the separation date carefully. Full timing guide.

Related calculators and guides

• How to Retire in 10 Years — if your timeline is tighter and the gap to close is larger
• How to Retire in 20 Years — if compound growth is still your primary lever and savings rate is the dominant variable
• How to Retire in 5 Years — the final sprint: proximity to FI is everything
• FIRE Number Calculator — FI number and years-to-FI from any starting point
• Coast FIRE Calculator — have you already crossed the coast threshold?
• FIRE Savings Rate Calculator — how savings rate determines your retirement date
• Rule of 55 Guide — penalty-free 401(k) access if you retire at 55+
• Roth Conversion Ladder Calculator — start your seasoning clocks now, not in year 13
• Safe Withdrawal Rate for Early Retirement — correct SWR for 30–40 year horizons
• Healthcare Before 65 — ACA bridge cost and MAGI coordination
• Taxable Brokerage Account Strategy — pre-59½ bridge for those retiring before 55
• 72(t) SEPP Calculator — if retiring at 52–54 and Rule of 55 doesn't apply
• Withdrawal Order Guide — four-constraint framework for tax-efficient draws
• Asset Allocation for Early Retirement — bond tent entry timing for the final 3 years
• Social Security Timing — zero-earnings impact and break-even analysis
• First Year of Early Retirement — the transition-year decision cluster
• Early Retirement Readiness Checklist — 20-item audit for the final year