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Guyton-Klinger Guardrails Calculator

Model dynamic retirement withdrawals. See how capital preservation and prosperity guardrails protect your portfolio while unlocking higher initial income.

$
Initial Income (4.5%)
$45,000/yr
$3,750/mo (+$5,000 vs 4% rule)
Capital Preservation Trigger
$833,333
If portfolio hits this, cut spending to $40,500/yr
Prosperity Raise Trigger
$1,250,000
If portfolio grows to this, raise spending to $49,500/yr

Not financial advice — a dynamic projection based on Guyton-Klinger rules.

How Guyton-Klinger Guardrails Work

Published by financial planner Jonathan Guyton and computer scientist William Klinger, the Guardrails framework replaces static spending with rules that respond to market cycles:

1. The Capital Preservation Rule (Downside Guardrail)

If a market drop pushes your effective withdrawal rate 20% above your starting rate (e.g. from 4.5% to 5.4%), you cut spending by 10%. This single adjustment prevents drawing down capital in bear markets.

2. The Prosperity Rule (Upside Guardrail)

If strong market gains reduce your effective withdrawal rate 20% below your starting rate (e.g. from 4.5% to 3.6%), you increase spending by 10%, giving you permission to enjoy portfolio gains.

Beyond a one-time estimate

Dynamic drawdowns require real-time tracking.

Connect your accounts and Fire Horizon monitors your effective withdrawal rate against your guardrail triggers automatically.

Runs on your real money

Link a brokerage with SnapTrade or Plaid, or drop in a CSV, and this exact chart tracks your actual balances — updating as markets move and you invest. No more re-typing estimates.

Tells you if you’re on track

Your Readiness score re-runs this Monte Carlo on your real net worth and answers what matters: on track for your age, will it last, is your emergency fund covered.

Your whole net worth, in one place

Investments, cash, property and debts together — with a savings rate pulled from your real deposits and your dividend income counted. All free.

Same math here and inside — every formula is hand-checkable on the methodology page.

Guardrail calculator questions

What is the Guyton-Klinger Guardrails withdrawal strategy?
The Guyton-Klinger Guardrails approach is a dynamic withdrawal strategy for retirement. Instead of withdrawing a fixed inflation-adjusted amount every year (like the traditional 4% rule), you adjust spending based on market performance using Capital Preservation (cutting spending when portfolio falls) and Prosperity rules (raising spending when portfolio grows).
Why do Guardrails allow a higher initial withdrawal rate?
Because you commit to making small spending cuts if a severe bear market hits, you significantly reduce sequence-of-returns risk. This safety net allows retirees to safely start with a 4.5% to 5.2% initial withdrawal rate instead of being restricted to 3.5%–4.0%.
How does the Capital Preservation Rule work?
If market losses cause your current withdrawal rate to rise more than 20% above your initial rate (e.g., rising from 5.0% to 6.0%), you reduce your annual spending by 10%. This prevents portfolio exhaustion during deep downturns.
How does the Prosperity Rule work?
If strong market gains cause your current withdrawal rate to fall 20% below your initial rate (e.g., dropping from 5.0% to 4.0%), you increase your annual spending by 10%, letting you enjoy your wealth during good times.

Set your dynamic withdrawal guardrails.

Free to start, no card required — link accounts via SnapTrade or Plaid, or import a CSV.

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