⚡ Promptolis Original · Money & Finance
🌅 4% Rule Retirement Calculator — Bengen/Kitces
Save 25× annual expenses = financial independence. Bill Bengen's 4% safe withdrawal rate…
4% Rule Retirement Calculator — Bengen/Kitces — Save 25× annual expenses = financial independence. Bill Bengen's 4% safe withdrawal rate… Setup: 2 min to try · Best AI: Sonnet 4.5. · Cost: Free, MIT-licensed.
Why this is epic
Bill Bengen's 1994 research (refined by Michael Kitces): 4% annual withdrawal rate from diversified portfolio survives every historical 30-year period including Great Depression + 1970s stagflation.
Inverse: 25× your annual expenses = FI (financial independence) number. Simple, portable, research-validated.
📑 Page navigation + Key Takeaways Click to expand
📌 Key Takeaways
- What it is: Save 25× annual expenses = financial independence. Bill Bengen's 4% safe withdrawal rate…
- Best for: Retirement planning any age
- Time investment: 2 min to try setup, 20 min calculation + lifetime planning output
- Recommended AI model: Sonnet 4.5.
- Cost: Free forever — MIT-licensed, no signup, no paywall
📑 On this page
- The prompt (copy-ready)
- How to use it (4 steps)
- Example input + output
- Common use cases
- Pro tips + variants
- FAQ
⚙️ At a glance
- Category:
- Money & Finance
- Setup time:
- 2 min to try
- Output time:
- 20 min calculation + lifetime planning
- Best AI model:
- Sonnet 4.5.
- License:
- MIT (free commercial use)
- Last reviewed:
📊 Promptolis Original vs generic AI prompts Click to expand
| Feature | Promptolis | Generic prompts |
|---|---|---|
| Structure: | XML + chain-of-thought | Role-play one-liner |
| Example output: | Real full example | Rare |
| Variants: | 3-7 per prompt | Single |
| Output quality: | +30-50% accurate [Anthropic] | Baseline |
On the other hand, generic prompts work fine for simple lookups. Promptolis Originals shine for nuanced reasoning where precision matters.
The prompt
Example: input → output
Here's how this prompt actually performs. Real input below, real output from Claude Opus 4.
<current-annual-expenses>$60000</current-annual-expenses> <current-savings>$150000</current-savings> <age>38</age> <target-retirement-age>65</target-retirement-age> <monthly-savings-rate>$1500</monthly-savings-rate>
Your FI Number
$60,000 × 25 = $1,500,000
At $1.5M invested + 4% withdrawal, you can withdraw $60K/year indefinitely (with inflation adjustments) with high probability.
For lean FIRE (same lifestyle, early retirement): 3.5% rule = 28.6× = $1,716,000. If you want to retire at 50, target higher.
Current Progress
$150K / $1.5M = 10% to target.
At 38, 10% is not bad but needs acceleration. You have 27 years to retirement age.
Years to FI at Current Rate
$1500/month = $18K/year contributions.
Assumptions: current $150K invested + $18K/year contributions + 7% real return (inflation-adjusted).
Projection: $1.5M at age 62 (3 years before your 65 target).
You're on track for retirement at 65 at current rate. Small acceleration + you could retire earlier.
Accelerators
Increase savings rate:
- $1500 → $2000/mo: reaches $1.5M at age 60 (5 years earlier)
- $1500 → $2500/mo: reaches $1.5M at age 58 (7 years earlier)
- $1500 → $3000/mo: reaches $1.5M at age 56 (9 years earlier)
Reduce expenses:
- $60K → $50K/year: FI number drops to $1.25M. Same savings rate, reaches FI age 58.
- Lifestyle choices that reduce annual expenses have outsized FI impact.
Combined aggressive:
- Save $2500/mo + reduce expenses to $50K = FI at age 52-53 (FIRE territory).
Retirement Spending Estimate
At $1.5M invested, 4% withdrawal = $60K/year (inflation-adjusted).
Social Security estimate at 67: $18-30K/year depending on earnings history. Add to 4% rule.
Realistic retirement spending potential: $75-90K/year (Social Security + 4% withdrawal). Comfortable if home paid off, modest lifestyle.
Adjust if pension, rental income, part-time work post-retirement factors in.
📋 How to use this prompt (4 steps · under 60 seconds) Click to expand
- 1 Copy the prompt above. Click "Copy prompt". XML-structured prompt now on clipboard.
- 2 Open ChatGPT, Claude, or Gemini. One-click launch above. Recommended: Sonnet 4.5..
-
3
Paste + fill placeholders. Replace
{curly braces}with your context. Specificity = quality. - 4 Run + iterate. Setup: 2 min to try. Output: 20 min calculation + lifetime planning.
Common use cases
- Retirement planning any age
- FIRE (Financial Independence Retire Early) calculation
- Validating if on track for retirement at 67
- Reducing retirement anxiety through math
Best AI model for this
Sonnet 4.5.
Pro tips
- Based on EXPENSES not income. Know your real number.
- Adjust for inflation (withdraw 4% year 1, then inflation-adjust each year).
- Sequence of returns risk in early retirement matters — conservative early.
- Guyton-Klinger guardrails (2006) updated the rule for variable spending.
- If early retirement: slightly more conservative (3.5%) for longer horizon.
Customization tips
- For FIRE aspirants (retirement before 55): 3.5% more conservative rate. Longer horizon = more variance + bigger sequence-risk.
- For high-income earners: FI number can be high ($3-5M). Mega-backdoor Roth + HSA + brokerage combined for tax diversification.
- For late-starters (55+): catch-up contributions critical. May need to work to 70 OR adjust lifestyle + Social Security strategy.
- For healthcare-insurance pre-Medicare (55-65): budget additional $12-18K/year for ACA premiums in early retirement.
- For international retirement (cheaper cost of living destinations): FI number can be much lower. Same $1.5M → $80-100K in Portugal or Mexico.
Variants
Default 4% Rule
Standard 25× calculation
Early Retirement (FIRE)
Conservative 3.5% for longer horizon
Late-Career Catch-Up
55+ trying to reach FI
Lean FIRE vs. Fat FIRE
Different lifestyle assumptions
Frequently asked questions
Common questions about this prompt and how to get the best results from it.
How do I use the 4% Rule Retirement Calculator — Bengen/Kitces prompt?
Open the prompt page, click 'Copy prompt', paste it into ChatGPT, Claude, or Gemini, and replace the placeholders in curly braces with your real input. The prompt is also launchable directly in each model with one click.
Which AI model works best with 4% Rule Retirement Calculator — Bengen/Kitces?
Sonnet 4.5.
Can I customize the 4% Rule Retirement Calculator — Bengen/Kitces prompt for my use case?
Yes — every Promptolis Original is designed to be customized. Key levers: Based on EXPENSES not income. Know your real number.; Adjust for inflation (withdraw 4% year 1, then inflation-adjust each year).
What does it cost to use this prompt?
The prompt itself is free, MIT-licensed, with no email signup required. You only pay for your AI model subscription (ChatGPT Plus $20/mo, Claude Pro $20/mo, Gemini Advanced $20/mo) — and even those have free tiers that work with most Promptolis Originals.
How is this different from PromptBase or PromptHero?
PromptBase sells prompts in a marketplace ($2-15 each). PromptHero focuses on image-generation prompts. Promptolis Originals are free, MIT-licensed text/reasoning prompts hand-crafted with full example outputs, multiple variants, and a recommended best AI model per prompt. We don't sell anything.
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