What is the FIRE number?

Your FIRE number is the total investment portfolio needed to retire and sustain your spending indefinitely. It is calculated as your annual spending divided by your safe withdrawal rate — typically 4%, giving a FIRE number of 25× annual spending.

What is the 4% safe withdrawal rate?

The 4% rule (from the Trinity Study) states that withdrawing 4% of your portfolio annually has historically been sustainable for 30+ years based on US stock market data. Many early retirees use 3–3.5% for longer retirement horizons or more conservative markets.

How does savings rate affect time to FIRE?

Savings rate has a dramatic effect. Saving 10% of income takes approximately 40 years to reach FIRE; saving 25% takes about 32 years; saving 50% takes around 17 years; saving 75% takes only 7 years. Both higher income and lower spending reduce your FIRE timeline.

FIRE Calculator — Years to Financial Independence & Early Retirement

How the 4% rule works

The 4% rule (from the Trinity Study) states that a diversified portfolio can sustain annual withdrawals of 4% indefinitely. This means your FIRE number is simply 25× your annual spending. A portfolio of $1M supports $40,000/year; £500k supports £20,000/year.

Your savings rate is the single most powerful lever. Moving from a 20% to a 30% savings rate doesn't just add 10% more money — it dramatically reduces your timeline because you're simultaneously building wealth faster and demonstrating you need less of it to retire.

FIRE-lommeregner — Finansiel uafhængighed, tidlig pension

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How the 4% rule works