Calculator Panel
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Enter your values above and click Calculate.
What This Calculator Does
This calculator lets you model and compare two primary withdrawal methodologies: the classic Constant Dollar (inflation-adjusted) method and the Variable Percentage method.
How to Use This Calculator
Enter your initial retirement portfolio value, desired annual withdrawal amount, inflation adjustment preference, expected inflation, and retirement duration to compare strategies.
How the Calculation Works
The underlying math engine processes your inputs using exact formulas. This systematic approach ensures professional, institutional-grade calculation precision:
Mathematical Formula
Formula Legend:
- · SWR_Rate = The safe withdrawal percentage selected (e.g. 4%).
- · Constant Dollar adjusts the initial amount for inflation, regardless of market performance.
- · Variable % adapts withdrawals to portfolio changes, preserving capital but causing fluctuating income.
Practical Example
Suppose you start retirement with a $1,000,000 portfolio, desire an initial annual withdrawal of $40,000 (4.0% SWR), adjust for inflation, and expect a 2.5% inflation rate:
Step-by-Step Mathematical Walkthrough:
- 1 In year 1, your withdrawal is $40,000.
- 2 In year 2, you adjust for inflation: $40,000 * 1.025 = $41,000 withdrawal, regardless of whether your portfolio went up or down.
- 3 In year 3, you adjust again: $41,000 * 1.025 = $42,025.
- 4 Over 30 years, you will withdraw a total of $1,756,024 under this constant-dollar method.
Important Assumptions & Notes
- Inflation occurs at a stable rate throughout the retirement period.
- The portfolio remains invested in a diversified mix of assets.
Common Mistakes or Considerations
- Rigidly following the 4% rule during a severe multi-year market crash instead of making minor, temporary spending adjustments to preserve capital.
Frequently Asked Questions
What is the 4% rule?
Derived from the Trinity Study, the 4% rule says that you can safely withdraw 4% of your portfolio in the first year of retirement, and adjust that dollar amount for inflation every year after, with a near-zero chance of running out of money over 30 years.
Should an early retiree use a lower withdrawal rate?
Yes. Because early retirement can last 40 or 50 years instead of 30 years, early retirees should aim for a lower initial withdrawal rate of 3.0% to 3.5% to ensure safety.