The Two Numbers That Matter
There are two ways to think about how much you need to retire, and they answer the same question from opposite ends:
- The 25× rule — your retirement number is roughly 25× your annual spending
- The 4% rule — a portfolio can sustainably support withdrawals of about 4% of its initial value per year
Both come from the same retirement-withdrawal research family (Bengen-style safe withdrawal studies and the Trinity Study), and they're algebraically the same: 1 ÷ 4% = 25.
If you spend $60,000/year, you need roughly $1.5M. If you spend $40,000/year, you need $1M. Cut your spending by 20% and your target drops by 20%.
See How Far You Are
Plug in your current savings, contribution, and timeline. The default scenario assumes 7% returns, 3% inflation, and retirement at 65:
What the 4% Rule Actually Says
The 4% rule is shorthand for: "a retiree who withdraws 4% of their starting portfolio in year one, then adjusts that dollar amount for inflation each subsequent year, would not have run out of money in any historical 30-year period."
It assumes:
- A 50–75% stock allocation
- A 30-year retirement
- Withdrawals from a tax-advantaged portfolio
It does not account for:
- Lifespans longer than 30 years (early retirement)
- Sequence-of-returns risk (a bad market in years 1–5 can break the rule)
- Spending changes (most retirees spend less in their 80s)
For early retirees (FIRE), many planners model a more conservative 3.25%–3.5% withdrawal rate, meaning 28–31× spending. For traditional retirees in their late 60s, 4% is still a useful starting point, and some plans can support 4.5–5% when the expected retirement horizon is shorter or spending is flexible.
Retirement Savings Benchmarks by Age
Fidelity publishes widely-cited age-by-age savings benchmarks as a multiple of annual salary:
| Age | Target multiple of salary |
|---|---|
| 30 | 1× |
| 35 | 2× |
| 40 | 3× |
| 45 | 4× |
| 50 | 6× |
| 55 | 7× |
| 60 | 8× |
| 67 | 10× |
So a 40-year-old earning $80,000 would use roughly $240,000 as a benchmark. These targets assume retirement at 67, a long-term stock-heavy mix, and contributions of about 15% of salary including employer match — which lines up with what the 401(k) calculator shows for the same inputs.
If you're behind, the fix isn't panic — it's increasing your savings rate by 1–2 percentage points and giving compounding more time. See the compound interest explainer for why even a few extra years of contributions matter so much.
Don't Forget Social Security
The Social Security Administration estimates the average retired-worker benefit after the 2026 COLA at about $2,071/month ($24,852/year). The maximum benefit for a worker retiring at full retirement age in 2026 is $4,152/month.
You can verify current figures in the SSA 2026 COLA fact sheet.
That income reduces what your portfolio has to cover. If you spend $60,000/year and expect $24,000/year from Social Security:
- Portfolio needs to cover $36,000/year
- 25× that = $900,000 target
That's a 40% reduction in your "number" — significant enough that ignoring Social Security can lead to over-saving, especially for middle-income workers whose benefits replace a meaningful share of pre-retirement income.
Inflation Is the Quiet Killer
A 30-year retirement at 3% inflation roughly doubles your cost of living. If you need $60,000/year today, the same lifestyle costs about $145,000/year in year 30.
This is why the 4% rule is inflation-adjusted — your withdrawal amount grows each year. Plans built on a fixed nominal number (e.g., "I'll spend $50,000/year forever") quietly run out of room.
A stock-heavy portfolio is the main inflation defense in retirement. Bonds, cash, and CD ladders are useful for sequence-of-returns risk and short-term spending, but the long-term growth has to come from equities.
FIRE: How the Math Changes
The Financial Independence / Retire Early movement uses the same math with two twists:
- Higher savings rate — often 40–70% of income, vs the traditional 15%
- More conservative withdrawal rate — 3.25–3.5% (28–31× spending) to handle longer retirement
A 30-year-old earning $100,000 and saving 50% can reach financial independence in ~17 years at 7% returns. The same earner saving 15% takes ~40 years. Savings rate matters far more than investment return in the accumulation phase.
Common Mistakes
- Targeting a round number with no math behind it. "I want to retire with $1M" is fine if your spending is $40k. It's not enough if it's $80k.
- Assuming a flat market. Plans that don't model sequence-of-returns risk break in the years they're tested.
- Ignoring healthcare costs before Medicare (age 65). Early retirees often underestimate this by $1,000–$2,000/month.
- Not increasing contributions with raises. A 1% bump in savings rate every raise can push your retirement age earlier by 3–5 years.
Key Takeaways
- The 25× rule and the 4% rule are the same equation
- Many people's actual number is lower than they think once Social Security is included
- For early retirement, use a more conservative 3.25–3.5% withdrawal rate (28–31×)
- Your savings rate matters more than investment returns
- Inflation roughly doubles your cost of living over a 30-year retirement
- Use the calculator above to test how saving 1–2% more changes your retirement age