Retirement Calculator Guide: The 4% Rule & Safe Withdrawals
Retirement planning is two questions: How much will I have? and How much can I spend? The first is a compound-interest problem; the second is the famous "4% rule." This guide explains both, plus how inflation quietly erodes the answer.
Part 1 — Building the Nest Egg
- FV — future value at retirement
- P — current savings
- PMT — annual contribution
- r — expected real return (after inflation)
- t — years to retirement
Using a real return (e.g. 5% instead of 8%) already accounts for inflation, so FV is in today's dollars.
Example: $50,000 saved, $10,000/year contribution, 5% real return, 30 years: FV = 50,000 × 4.32 + 10,000 × 66.4 ≈ $880,000 in today's purchasing power.
Part 2 — The 4% Safe Withdrawal Rate
The "4% rule" comes from the Trinity Study: withdrawing 4% of your starting portfolio in year one, then adjusting that dollar amount for inflation each year, sustained a 30-year retirement through nearly every historical market — including retiring just before a crash.
This is a guideline, not a guarantee. Many advisors now suggest 3.5% for longer retirements or conservative portfolios.
Our $880,000 nest egg × 4% = $35,200/year retirement income, on top of Social Security.
Inflation Is the Silent Thief
$35,200 in 2056 dollars buys far less than $35,200 today. At 3% inflation, purchasing power halves in ~24 years. Always plan in real (inflation-adjusted) terms, and ensure your portfolio's growth outpaces inflation.
If the market crashes in your first 2–3 retirement years, you're forced to sell at low prices, depleting the portfolio faster. A 2-year cash buffer helps you avoid selling during a downturn.
Don't Forget Taxes
Withdrawals from traditional 401(k)/IRA are taxed as ordinary income; Roth withdrawals are tax-free. So $35,200 from a traditional account might net only ~$30,000 after federal tax. Mix account types (taxable + Roth) for flexibility.
Put It Into Practice
Enter your current age, savings, contributions, and expected return to project your nest egg and estimate annual retirement income.
退休规划就是两个问题：我届时能有多少退休金？和我每年能花多少钱？第一个是复利问题；第二个就是著名的"4% rule"。本指南将详细解释两者，以及 inflation 如何悄然侵蚀你的退休金。
第一部分 — 建立 retirement nest egg
- FV — 退休时的未来值
- P — 当前储蓄
- PMT — 每年投入金额
- r — 预期实际回报（扣除 inflation 后）
- t — 距退休的年数
使用实际回报（例如 5% 而非 8%）已经考虑了 inflation 因素，因此 FV 是以当前美元计价。
示例：已储蓄 $50,000，每年投入 $10,000，实际回报率 5%，30 年：FV = 50,000 × 4.32 + 10,000 × 66.4 ≈ $880,000（以当前购买力计）。
第二部分 — 4% 安全 withdrawal rate
"4% rule"源自 Trinity Study：在第一年提取起始投资组合的 4%，之后每年根据 inflation 调整该金额，这种策略在几乎所有历史市场中都能维持 30 年的退休生活——包括在市场崩盘前夕退休的情况。
这是一个指导原则，而非保证。许多顾问现在建议对于更长的退休期或保守型投资组合使用 3.5%。
我们的 $880,000 retirement nest egg × 4% = $35,200/年的退休收入，此外还有 Social Security。
Inflation 是无声的窃贼
2056 年的 $35,200 购买力远不及今天的 $35,200。以 3% 的 inflation 计算，购买力约在 24 年内减半。务必以实际（经 inflation 调整后的）金额规划，并确保投资组合的增长速度超过 inflation。
如果在退休的前 2–3 年市场崩盘，你将被迫以低价卖出资产，加速消耗投资组合。持有 2 年的现金储备可以帮助你在市场低迷期避免卖出。
别忘了税款
从传统 401(k)/IRA 提取的资金按普通收入征税；Roth 账户的提取则免税。因此，从传统账户提取 $35,200，扣除联邦税后实际到手可能只有约 $30,000。建议混合使用不同类型的账户（应税账户 + Roth）以增加灵活性。
付诸实践
输入你当前的年龄、储蓄、投入金额和预期回报，来预测你的 retirement nest egg 并估算每年的退休收入。
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