Free Retirement Savings Calculator — Future Value + 4% Rule + FIRE Number

What This Calculator Does

This tool projects how much money you will have at retirement given your current savings, annual contributions, years remaining, and expected return. It then converts that future balance into three numbers people actually need: the 4% rule annual income (how much you can safely withdraw each year), the FIRE number(the savings target that lets you retire indefinitely), and — if you enter a target spending amount — how many years your portfolio will last. The math is the standard future-value-of-an-annuity formula used by every 401(k) plan provider, actuary, and financial planner, applied with monthly compounding so projections match how real accounts actually grow.

Most retirement calculators stop at the raw balance. This one goes further: it asks what can you spend from that balance?That translation — from a pile of dollars to an annual income stream you can sustain for 30 or more years — is where most retirement planning fails. A $1.5M balance sounds comfortable until you realize it supports only $60,000 per year under the 4% rule, before taxes, before inflation adjustments, and before sequence-of-returns risk takes its cut.

The Future-Value Formula Explained

Your projected retirement balance is the sum of two compounding streams: the lump sum you already have, and the contributions you will add over time. Each follows a slightly different formula; added together, they give your total projected balance.

FV = P × (1 + r/12)^(12t) + PMT × [((1 + r/12)^(12t) − 1) ÷ (r/12)]
where P = current savings, PMT = monthly contribution (annual ÷ 12), r = annual return rate (decimal), t = years to retirement

The 4% rule translates the future balance into annual income. Divide the projected balance by 25 to find the safe annual withdrawal, or multiply your desired annual spend by 25 to find the FIRE number you need to accumulate. Both operations are the same arithmetic flipped: a 4% withdrawal rate on a $2M portfolio is $80,000/year; a $80,000/year spending goal requires a $2M portfolio.

Annual income = FV × 0.04       FIRE number = annual spend × 25
The 0.04 withdrawal rate (4%) was calibrated on 1926–2015 US market data. The 25× multiplier is its direct algebraic inverse.

Three Worked Examples

Three realistic scenarios computed with the same formula this calculator uses. Copy any set of inputs into the fields above to reproduce the full result card, then experiment with your own numbers.

Contribution Rate by Scenario — What Does It Take?

The most practical question is not what you will have, but what you need to contribute to reach a specific goal. The table below holds the retirement age at 65, the return at 7%, and varies only the starting age and current savings. Each row shows the annual contribution needed to accumulate $1.5M — a target that supports roughly $60,000/year under the 4% rule.

How to Use This Calculator

1. Enter your current age and retirement age. The gap between them is the compounding horizon — the single most powerful input in the formula. Every extra year compounds on the previous year’s growth; at 7%, a 35-year horizon is worth roughly twice as much as a 25-year horizon per dollar contributed.
2. Enter your current retirement savings— the total balance across every account you earmark for retirement: 401(k), Traditional IRA, Roth IRA, Roth 401(k), taxable brokerage, HSA. Do not include emergency funds or cash you plan to spend in the next decade. Include your current 401(k) balance at its statement value, not any estimate of future contributions.
3. Enter your annual contribution — the total you and your employer will add this year. For a 401(k) with a 50% employer match on the first 6% of a $100,000 salary, that is $18,000 of your own contributions plus $3,000 of match = $21,000 total. The calculator divides by 12 internally; monthly cadence is correctly captured.
4. Enter your expected annual return. The default of 7% reflects the long-run real return of a diversified 70/30 stock-bond portfolio. For a more conservative stress test, use 5%. For an optimistic scenario (heavier equity allocation, younger investor), 8–9% is defensible. See the section below on realistic return assumptions.
5. Optionally, enter a target annual withdrawal— what you plan to spend per year in retirement (in today’s dollars). The calculator returns your FIRE number (25× that amount), whether your projected balance clears it, and approximately how many years the portfolio will sustain that withdrawal before depletion.

What Is a Realistic Expected Return?

The 7% default is a deliberate compromise. The S&P 500’s nominal return from 1928–2024 averages approximately 10%; subtract 3% long-run inflation and you get roughly 7% real. A balanced 70/30 stock-bond portfolio has historically delivered 6.5–7% real over rolling 30-year windows. But three forces push the honest planning number lower:

• Starting valuations matter.Historical research consistently shows that high CAPE ratios (cyclically adjusted price-to-earnings) predict below-average forward returns. Most major asset managers — Vanguard, BlackRock, Research Affiliates — project US equities at 4–6% real over the coming decade from 2026 starting valuations, not 7%.
• Glide-path drag.A portfolio that starts 90% equity at 30 will typically drift toward 40–50% equity by 65 as you reduce risk. Bond returns are structurally lower than stock returns; as the equity share declines, so does the blended return. The calculator uses a single constant rate — but reality is a declining return as you age. Model the last decade at 1–2% below your accumulation assumption.
• Fee drag compounds mercilessly. A 1% advisory fee plus 0.5% fund expense ratio (typical in actively managed products) removes 1.5%/year from your return. Over 35 years at 7% nominal, a 1.5% fee drag reduces the ending balance by roughly 40%. Index funds with 0.03–0.10% expense ratios make the full return available.

A defensible practice: plan around the 5% real scenario (conservative), treat the 7% real scenario as the most likely outcome, and note the 9% real scenario as the upside. Build your savings rate around the 5% scenario; if returns are better, you retire earlier.

Sequence-of-Returns Risk: Why Order Matters

The future-value formula assumes a single constant return every year. Real markets deliver a sequenceof returns — some years +30%, others −40% — and in retirement, the order of those returns matters enormously. This is sequence-of-returns risk.

Consider two retirees, each with a $1M portfolio withdrawing $40,000/year at 4%. Retiree A experiences a 30% loss in year 1 of retirement (portfolio drops to $700,000, then they withdraw $40,000 — $660,000 left). Even if the market averages 7% from year 2 onward, the portfolio must compound from a permanently reduced base. Retiree B experiences the same 30% loss in year 20 instead of year 1 — by then, 19 years of 7% growth have built a large enough cushion that the same loss barely dents the long-run trajectory. The math is identical in terms of average returns; the outcome is wildly different based on timing.

Two practical mitigations: hold 2–3 years of spending in cash or short-term bonds at retirement so you never sell equities into a crash, and consider starting with a 3.5% withdrawal rate instead of 4% in the first five years. The second adjustment alone eliminates most historical failure scenarios. For a rigorous probability-based stress test, pair this calculator with the FIRE Monte Carlo calculator, which runs 500 historical sequence simulations to show the probability distribution around your specific plan.

The 4% Rule Scenarios: What Your Balance Actually Buys

Common Mistakes When Planning Retirement Savings

• Using nominal returns instead of real returns.A 10% nominal return becomes roughly 7% real after 3% inflation. If you enter 10% and interpret the output in future-dollar terms, the projected balance is accurate — but $2M in nominal future dollars is not $2M in today’s purchasing power. Use real returns (post-inflation) to get results in today’s dollars, which is what this calculator’s default reflects.
• Omitting the employer match. A 50% match on the first 6% of a $100,000 salary is $3,000 in free money. Leaving it out of the annual-contribution field understates the projection by 10–20% depending on salary and match terms. Always include the full match-eligible contribution and the match itself.
• Assuming contributions stay constant in nominal dollars. Real careers see salary rise 3–5% per year. A $12,000 contribution today is likely $20,000 in 15 years in nominal terms. The calculator uses the fixed value you enter; re-run it every few years with updated contribution levels to stay accurate.
• Forgetting taxes on traditional account withdrawals.A traditional 401(k) or IRA balance is fully pre-tax. A $1.5M traditional balance typically produces only $1.05–1.2M in after-tax retirement income at a 20–30% effective marginal rate. Roth account balances are fully post-tax — what you see is what you spend. A mixed portfolio needs the traditional balance haircut. The calculator does not model taxes; subtract your expected effective retirement rate from the withdrawal for a realistic net-income number.
• Not running a stress test at 5% return. The single most dangerous mistake is building a retirement plan that only works at 7%+. Run every scenario at 5% as a conservative floor. If the 5% scenario still clears your FIRE number, you have genuine margin of safety. If only 7% clears it, you are one bad decade from working longer.
• Confusing the FIRE number with the annual savings target. The FIRE number is the total balance you need at retirement. Your annual savings target is whatever contribution rate accumulates that total from your current balance over your remaining working years. If you enter the FIRE number as the annual contribution, you will project a wildly incorrect result.
• Ignoring Social Security’s role.Social Security is additive to the 4%-rule income and substantially reduces the FIRE number you actually need from savings alone. A household expecting $30,000/year in combined Social Security benefits and targeting $75,000/year in total retirement income only needs $45,000/year from savings — a FIRE number of $1,125,000, not $1,875,000. Check your Social Security estimate at the SSA website before building your target.

When This Calculator Decides For You

The calculator’s output almost always maps to a concrete choice. The five that come up most often:

1. Whether to contribute beyond the employer match. Run two scenarios: one with match-level contributions, one with the IRS annual 401(k) limit ($23,500 for under-50s in 2026). The future-value difference is your lifetime cost of stopping at the match. For most savers in their 30s, that gap exceeds $400,000 by retirement.
2. Whether you can retire 5 years earlier than planned. Enter your target age; then enter target minus 5. The earlier scenario simultaneously shortens the compounding window and lengthens the withdrawal years. If the earlier balance still clears the 4% FIRE number comfortably, the early retirement is mathematically supported. If it does not, the gap tells you the required extra savings rate to close it.
3. How much the side income is actually worth.If a side project adds $10,000/year of investable income, enter it as additional annual contribution for the years you plan to run it. At 7% real and a 20-year remaining horizon, an extra $10,000/year adds roughly $440,000 to the retirement balance — equivalent to nearly 6 years of additional work in some scenarios.
4. Whether the Roth conversion makes sense.A Roth conversion affects your current-year taxable income but converts pre-tax savings to post-tax. The calculator does not model the conversion itself, but you can compare two scenarios — the current trajectory versus a trajectory where a converted lump is included in after-tax investments (adjusted for the tax owed) — to see whether the long-run difference justifies the current-year tax hit.
5. Whether the current pace is on track. Enter your numbers and compare the projected balance to your FIRE number. If the balance clears it at 7% and at 5%, you are solidly on track. If it only clears at 7%, you have meaningful risk exposure. If it misses at both, the calculator tells you the size of the gap, which you close by contributing more, retiring later, or targeting a lower withdrawal rate.

Retirement Savings Glossary

Eight terms that appear in every retirement planning conversation. Skim the snippet for the one-line definition; expand the card for the full explanation.

Related Planning Tools

Retirement savings is the accumulation phase; several tools cover the surrounding decisions. Use the compound interest calculator to model any single account without the retirement-specific framing — useful for Roth IRAs or taxable brokerage. Use the Roth vs Traditional 401(k) calculator to see whether pre-tax or post-tax contributions produce a better outcome given your current and expected future tax rates. For the Social Security claim-age decision (which year to start claiming benefits), use the Social Security break-even calculator. And once you have a target balance, the inflation calculator translates the real-return number into the nominal future-dollar balance, useful for setting expectations with a financial advisor who works in nominal terms.