Calculator
Retirement guardrails calculator
Set your starting spending and your guardrails. We test the rules against every 30-year stretch since 1928 and show when you’d cut, when you’d raise, and how low spending would go.
68 of 69 past retirements, each starting in a different year from 1928 to 1996, lasted the full 30 years starting at $45,000 a year (4.5% of savings). In those starts, spending never fell below $36,000.
Your guardrails
| Rule | When | What to do |
|---|---|---|
| Lower guardrail | Your withdrawal tops 5.4% of savings. At $45,000 a year, that means savings below $833,000. | Cut spending 10%, but never below $36,000 |
| Upper guardrail | Your withdrawal falls under 3.6% of savings. At $45,000 a year, that means savings above $1,250,000. | Raise spending 10% |
| Any other year | Between the guardrails | Raise spending with inflation only |
The percentages stay fixed. The dollar amounts move as your spending changes: always compare this year’s withdrawal with this year’s savings.
- Guardrails
- Fixed spending
What this means
Starting at $45,000 a year from $1,000,000 (4.5%), these guardrails lasted 30 years in 99% of historical starts. The same spending held fixed lasted in 84%. The start that fell short was 1966, heading into the high inflation of the late 1960s and 1970s.
Guardrails let you start higher because you agree in advance to cut back if a bad stretch arrives. With these rules, the highest starting spending that lasted through every start was $44,500 a year (4.45%), against $37,000 (3.70%) for fixed spending. The price is a budget that moves: in a typical retirement you’d cut 3 times and raise 4 times.
Retiring in 2000, these rules cut spending in 2003, 2006 and 2009. The money lasted through 2025, with spending at its lowest $36,000.
Wider guardrails and smaller changes mean fewer, gentler adjustments but less protection. A higher floor protects your lifestyle but lets savings fall further in the worst starts. This is a test against past markets, not a forecast.
How retirement guardrails work
Guardrails are spending rules you agree to before you retire. Your starting withdrawal rate sits between two lines. If markets fall and your withdrawal grows too large a share of what’s left, you cross the lower guardrail and cut spending. If markets rise and it shrinks, you cross the upper guardrail and give yourself a raise. In every other year, spending simply keeps pace with inflation.
With the starting numbers above, $45,000 from $1 million is a 4.5% withdrawal. With 20% guardrails, you’d cut 10% if your withdrawal topped 5.4% of savings (savings below about $833,000) and raise 10% if it fell under 3.6% (savings above about $1.25 million). The table in the results shows the triggers for your own numbers.
Where the rules come from
Financial planners Jonathan Guyton and William Klinger published guardrail rules in the Journal of Financial Planning in 2006. Their insight: retirees willing to make modest, pre-agreed cuts after bad markets could start with a meaningfully higher withdrawal than the classic 4% rule.
This calculator keeps their core rules, a 20% band with 10% changes, and lets you change both. It adds a spending floor and leaves out one of their extra rules (skipping inflation raises after losing years), so the results are easy to follow. The assumptions below list every rule we apply.
Choosing your settings
- Guardrail width. 20% is the width Guyton and Klinger used. Narrower rails adjust more often; wider rails adjust rarely but let savings drift further first.
- Size of each change. 10% is the classic step. Smaller steps feel gentler but may need to repeat in a long downturn.
- Spending floor. Set it at the least you could really live on. A high floor protects your lifestyle, but in the worst starts it lets savings run lower.
- Replay a start year. Pick 1929, 1966 or 2000 to watch the rules work through a real crash, year by year.
Guardrails vs the 4% rule
With these default rules and 60% stocks, the highest starting spending that lasted through every 30-year start since 1928 was $44,500 a year per $1 million, against $37,000 for spending held fixed. That difference is the reward for accepting a budget that moves. See the 4% rule vs guardrails comparison for the two side by side.
Assumptions
- Each year, compare that year’s withdrawal with your savings. If the rate is more than 20% above where it started, cut spending 10%. If it is more than 20% below, raise spending 10%. Otherwise, raise spending with inflation only.
- Spending is never cut below 80% of the first year’s amount. If the money runs out, the start counts as falling short.
- This is a simplified version of the rules Jonathan Guyton and William Klinger published in 2006. It leaves out their extra rule of skipping inflation raises after losing years.
- 60% S&P 500 stocks and 40% 10-year Treasuries, rebalanced yearly. Every 30-year stretch since 1928 is tested. No taxes, fees or Social Security.
New to a term? See the retirement income glossary.
Common questions
What guardrail width should I use?
20% is the width Guyton and Klinger used and a common starting point. Narrower rails, such as 10–15%, adjust more often in smaller steps; wider rails, such as 25–30%, adjust rarely but let your savings drift further before acting. Try both in the calculator above.
What happens if I hit my spending floor?
Spending stops falling at the floor even if savings keep dropping, so in the very worst starts the money can still run out. Starting at $45,000 from $1 million with 20% guardrails and an 80% floor, that happened in 1 of 69 historical starts: 1966, in year 30.
How do I check my guardrails each year?
Once a year, divide this year’s planned withdrawal by your current savings and compare it with your two guardrail rates. If it is above the upper rate, cut; if below the lower rate, raise; otherwise adjust for inflation only. Our Live mode runs this check for you each January.
Related tools
How we calculate this
We replay your starting spending and guardrail rules through every 30-year stretch of U.S. market history since 1928. At the start of each year we check the withdrawal rate against your guardrails, adjust spending if one is crossed, take the withdrawal, then apply that year’s real return.
Data: S&P 500 total returns, 10-year Treasury and 3-month Treasury bill returns as compiled by Aswath Damodaran (NYU Stern), and CPI-U inflation from the U.S. Bureau of Labor Statistics, 1928–2025 (January 2026 update). Read the full methodology and limitations.