FIRE Number Calculator

Calculate your FIRE number — the total savings needed to retire early. Uses the 4% rule. See years to FIRE based on your

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Enter Your Details

What you spend per month in retirement
SA equity average ~10–12% long-term before inflation

Your Results

Your FIRE Number
R6,000,000
Monthly Income in Retirement
R20,000
Annual Expenses
R240,000
Years to FIRE
FIRE Age (if 30 now)
Still Need to Save

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What Is a FIRE Number?

Your FIRE number is the total amount of savings and investments you need to retire early and sustain your lifestyle indefinitely — without ever running out of money. FIRE stands for Financial Independence, Retire Early, a global movement of people who choose to save aggressively so they can stop working decades before traditional retirement age.

The 4% Rule — Where Does It Come From?

The 4% rule comes from the Trinity Study, a landmark 1998 research paper by three professors at Trinity University in Texas. They analysed decades of US stock market and bond data and found that a portfolio invested in a mix of stocks and bonds could support a 4% annual withdrawal rate indefinitely — surviving even the worst historical market downturns, including the Great Depression.

In simple terms: if you withdraw 4% of your portfolio each year, historical data suggests your money will last 30+ years in most scenarios. Many FIRE practitioners use 3% or 3.5% for extra security, especially if retiring very early.

How to Calculate Your FIRE Number

The formula is simple: FIRE Number = Annual Expenses ÷ Safe Withdrawal Rate

For example: R20,000/month × 12 = R240,000/year. At 4%: R240,000 ÷ 0.04 = R6,000,000. That is your target — R6 million in invested assets.

South African Considerations

South African investors need to account for rand depreciation, local inflation (historically 5–7%), and the JSE's long-term returns (roughly 10–14% nominal, 5–8% real). Many SA FIRE practitioners invest in a mix of JSE-listed assets and offshore exposure via TFSA and RA contributions for tax efficiency. Our SA FIRE calculator (RA + TFSA) handles these specifics in detail.

Frequently Asked Questions

The 4% rule states that you can withdraw 4% of your portfolio annually without running out of money over a 30+ year retirement. It comes from the 1998 Trinity Study. Many early retirees use 3–3.5% for added safety.

The calculator uses standard financial mathematics and your inputs. It cannot predict future market returns or inflation. Use it as a planning guide, not a guarantee. Conservative assumptions are always safer.

The 4% rule was based on US data. South African investors face higher inflation and currency risk. Many SA FIRE practitioners use 3–3.5% to be safe, and invest offshore to reduce rand risk.

Focus on what you can control: your savings rate and your expenses. Reducing monthly expenses by R2,000 reduces your FIRE number by R600,000 at a 4% rate. Small spending cuts have a massive impact on your target.

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⚠️ Disclaimer: All calculations are estimates based on your inputs. They are not financial advice. Consult a qualified financial advisor before making any investment or retirement decisions.
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