schedule Last updated: June 2026 | Strategy Ready

Coast FIRE Compounding Engine Calculator

Find your financial tipping point where existing capital naturally grows to full retirement limits.

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Financial Metrics

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Current Age

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Current Net Worth ($)

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Monthly Investment ($)

Monthly Expenses in Retirement ($)

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Expected Annual Return (%)

Safe Withdrawal Rate (%)

Your FIRE Projections

NovusTools FIRE Report

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Your Target FIRE Age

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Years to FI

Target Net Worth

Coast FIRE Number

The amount needed today to retire at 65 without ever investing another dime.

The Mechanics of Coast FIRE: Compounding Horizons Without Active Savings

Coast FIRE is a milestone achieved when you have front-loaded your investment engine so heavily at an early stage that your current portfolio will naturally compound to cover your traditional age-65 retirement target—without you ever adding another dollar of active savings. Once you cross this mathematical threshold, your current savings rate requirements permanently drop to absolute zero.

This structural shift completely alters your immediate income needs. Since you no longer need to violently save 30% to 50% of your paycheck for future retirement security, you can confidently downshift your career immediately. You only need to earn enough to cover your immediate monthly operational costs, opening the door to passion projects, low-stress contracting, starting a business, or extended travel.

Age Milestone	Years until Age 65	Required Capital Multiplier (7% Real Return)
Age 25	40 Years	~15.0x Growth Potential (Requires low initial capital)
Age 35	30 Years	~7.6x Growth Potential
Age 45	20 Years	~3.8x Growth Potential (Requires high initial capital)

Methodology & The Math Behind FIRE

The Trinity Study & 4% Rule

Our Safe Withdrawal Rate (SWR) logic is rooted in the widely cited 1998 Trinity Study. It dictates that withdrawing 4% of your portfolio annually, adjusted for inflation, historically yields a 95%+ success rate of never depleting your assets over a 30-year retirement period.

Inflation-Adjusted Growth

The default 7% expected return is a real return metric. We assume a historical S&P 500 average return of 10%, minus a 3% average inflation rate. This ensures your Target FIRE Number retains its true purchasing power in future decades.

Frequently Asked Questions

How do you calculate the exact Coast FIRE metric?

The algorithm first determines your absolute target retirement number at age 65 (using the 4% rule). It then reverse-compounds that final figure backward to your current age using an inflation-adjusted (real) expected annual market return rate (typically 5% to 7%). The resulting number is your Coast FIRE tipping point.

Is Coast FIRE risk-free?

It relies heavily on the assumption that global stock markets will continue to average historical returns over a multi-decade horizon. If you achieve Coast FIRE but experience a "lost decade" in the stock market, your trajectory could fall short. To mitigate this, many practitioners over-save by an additional 20% before officially shifting to Coast mode.