About
Trinity Study (1998): a 4% initial withdrawal, adjusted for inflation, lasted 30 years in 95% of historical 30-year periods (60/40 portfolio). Critics: no future return guarantee; sequence risk in early years; healthcare inflation higher than CPI.
The shorthand is the 25x rule: multiply your target annual spending by 25 and that is the portfolio number. A household that needs $80,000 a year needs $2.0 million; $120,000 a year needs $3.0 million. Bill Bengen, who first published the 4% number in 1994, later revised his own work to 4.7% after expanding the asset mix to include small-cap value and international equities. Morningstar's 2025 update lowered the starting safe rate to 3.7% for retirees who want a 90% success rate over 30 years with current bond yields.
Common pitfalls
- Forgetting taxes. The 4% is gross. A taxable brokerage withdrawal of $60,000 may net closer to $50,000 after federal and state tax in a high-cost state. Build your spending target around the after-tax number.
- Ignoring sequence-of-returns risk. A 30% market drop in years one to three of retirement is far more damaging than the same drop in year 20, because withdrawals lock in the loss on a shrunken base.
Formula
Frequently asked questions
How accurate is the 4% Rule Calculator?
It applies the standard formula. Accuracy is limited only by your input precision. For decisions with material consequences (taxes, medical, legal, structural), use the result as a starting point and verify with a qualified professional in the relevant field.
Is the 4% Rule Calculator free to use?
Yes. 100% free, no signup, no payment, no API key. The site is funded by display ads around the tool but not inside the calculation flow.
Are my inputs saved anywhere?
No. All inputs stay in your browser tab. Closing the tab discards them. The site uses Google Analytics for traffic measurement (anonymized) but the analytics never see what you type into the form.
Can I use the 4% Rule Calculator on my phone?
Yes. The tool is responsive and tested on iOS Safari, Android Chrome, and major desktop browsers. Touch targets meet Apple's 44pt and Google's 48dp minimum.
Does the 4% Rule Calculator work offline?
Yes. Once the page has loaded, it works without internet. The calculation runs in JavaScript on your device.
How do I report a bug or suggest improvement to the 4% Rule Calculator?
Email hi@3tej.com with the URL of this page and a description of what you saw vs expected. We typically respond within 72 hours.
Can I share results from the 4% Rule Calculator?
Take a screenshot or copy the output. The page doesn't generate shareable URLs for specific calculations - inputs stay in your browser only.
Why are the results different from another 4% rule tool?
Most likely: different formula assumptions, different default values, different rounding rules, or different applicable rates. Check the methodology if both tools document it. Both can be valid for different scenarios.
Is the 4% Rule Calculator accurate?
The 4% Rule Calculator applies the standard formula for 4% rule. Accuracy is limited only by your input precision. For decisions with material consequences, use the result as a starting point and verify with a qualified professional or the relevant official source.
Is the 4% Rule Calculator free?
Yes. 100% free, no signup, no payment, no API key. The site is funded by display ads that appear around the tool but not inside the calculation flow.
Are my inputs saved?
No. Inputs stay in your browser tab. Closing the tab discards them. The site uses Google Analytics for traffic measurement (anonymized) but does not see what you type into the form.
How to use the 4% Rule Calculator
The 4% Rule Calculator is a browser-based tool that runs entirely on your device. Inputs you enter never reach a server - all calculations happen client-side in JavaScript. This means:
- Privacy: nothing is logged, sent, or stored by 3Tej. Inputs disappear when you close the tab.
- Speed: results update as you type. No network round trip.
- Offline use: once the page is cached, it works without internet.
- No signup: no account, no email, no rate limits.
Step by step
- Enter your inputs in the form above. Each field is labeled with its unit (currency, percent, kg, etc.) and the expected range.
- Read the result as it updates. The number reflects the formula commonly accepted in 4% Rule-related calculations.
- Adjust to see sensitivity: change one input at a time and watch how the output moves. This is the fastest way to understand which variable matters most.
- Copy or screenshot the result for later reference. The page state persists for the session if your browser allows it.
When you would use this
- Quick estimates: when you need a number now and don't want to open a spreadsheet.
- Sensitivity analysis: testing how a result changes as inputs vary, before committing to a real-world decision.
- Comparison: running the same calculation with different inputs to compare options side by side.
- Learning: building intuition for how the underlying math behaves.
- Documentation: capturing a snapshot of inputs and outputs at a point in time.