Calculating your FIRE number (4% rule) is straightforward once you know the FIRE Number formula and what each input means. This guide explains the method in plain language, walks through a manual calculation, and gives worked examples you can follow — then you can do it instantly with the FIRE Number Calculator.
What is FIRE Number?
The FIRE Number calculation tells you your FIRE number (4% rule) from a few simple inputs. The figure you are solving for here is the FIRE number (4% rule), expressed in INR.
The FIRE Number formula
The core formula is:
FIRE number (4% rule) = Annual expenses in retirement × 25Here is what each input means:
- Annual expenses in retirement — a money amount. Example: ₹6,00,000.
How to calculate it step by step
- Write down the annual expenses in retirement (for example, ₹6,00,000).
- Apply the formula above to get your FIRE number (4% rule).
- Double-check the result with the FIRE Number Calculator.
Worked examples
Example 1
| Input / Output | Value |
|---|---|
| Annual expenses in retirement | ₹6,00,000 |
| FIRE number (4% rule) | ₹1,50,00,000 |
| Conservative target (3% rule) | ₹2,00,00,000 |
With annual expenses in retirement of ₹6,00,000, the FIRE number (4% rule) works out to ₹1,50,00,000.
Example 2
With annual expenses in retirement of ₹12,00,000, the FIRE number (4% rule) works out to ₹3,00,00,000.
| Result | Value |
|---|---|
| FIRE number (4% rule) | ₹3,00,00,000 |
| Conservative target (3% rule) | ₹4,00,00,000 |
Example 3
With annual expenses in retirement of ₹3,00,000, the FIRE number (4% rule) works out to ₹75,00,000.
| Result | Value |
|---|---|
| FIRE number (4% rule) | ₹75,00,000 |
| Conservative target (3% rule) | ₹1,00,00,000 |
Tips for an accurate result
- Keep your units consistent — mixing, say, months with years or grams with kilograms is the most common source of error.
- Round only at the very end. Rounding inputs early can shift the final answer noticeably.
- Re-run the numbers whenever an input changes, rather than estimating from an old result.
- Annual rates must be converted to the period you are calculating for (for example, divide an annual rate by 12 for a monthly figure).
Prefer not to do the maths by hand? — the FIRE Number Calculator does it instantly, for free, with the formula and a worked example built in.
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