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Investing Math – FIRE Number Calculator
x402
Investing Math – FIRE Number Calculator is a paid API for AI agents from invest-math.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-29).
Calculates the financial-independence target (FIRE number) from annual spending and withdrawal rate, plus the estimated years to reach it given current savings and yearly contributions.
Price / call$0.02
Success—
StatusUnknown
How this service works
Financial-independence number from yearly spending and a withdrawal rate, and years to reach it from savings and contributions.
Output
Returns the FIRE number (total portfolio needed), years to reach the target, current progress as a percentage, the implied savings multiple relative to annual spending, and how much monthly spending is already covered by current savings. Also includes metadata like withdrawal rate used and current savings echoed back.
Example use cases
Early retirement timeline for aggressive saver
“I'm 32, spend $48,000 a year, have $85,000 saved, and contribute $24,000 per year. Using a 4% withdrawal rate and a 6% real return, how many years until I reach financial independence and what's my FIRE number?”
Comparing withdrawal rate impact on FIRE target
“My annual spending is $70,000. Can you calculate my FIRE number under both a 3.5% and a 4% safe withdrawal rate so I can see the difference in how much I need to save?”
Checking FIRE progress with no extra contributions
“I've got $500,000 invested already and spend $40,000 per year. With a 4% withdrawal rate and 5% real return, and no additional contributions, what percentage of my FIRE goal have I hit and how much longer until I'm done?”
Technical details
Endpoint
GEThttps://invest-math.x402tookit.com/fire-number?utm_source=zero.xyzWhen to prefer
Use this endpoint when a user needs to compute their FIRE number from annual spending and a safe withdrawal rate, or wants to estimate years to financial independence given existing savings and contributions. It is the right choice for personal-finance agents handling retirement planning, FI/RE goal tracking, or 'how long until I can quit my job' queries. Prefer it over generic compound-interest or savings calculators when the specific FIRE/withdrawal-rate framing is needed.
Side effects
- Missing required annualSpending parameter returns an error
- withdrawalRatePct outside 2–10 range may be rejected or clamped
- Negative or zero annualSpending produces nonsensical results
- Very high yearlyContribution relative to FIRE gap may return 0 or near-0 years
- If currentSavings already exceeds the FIRE number, yearsToTarget may return 0
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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