fire-number-calc: Fire number and timeline math for early retirement planning

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The arithmetic behind a fire number: the balance a withdrawal rate has to support, the gap between today's balance and that target, and the years of saving it takes to close the gap when the portfolio compounds at a fixed return.

The timeline function also prices a growing budget: a spending target that rises each year before retirement pushes the crossing point out, and the difference between the flat and growing timelines is the working-year cost of that growth.

Companion to Firenomics, which publishes the withdrawal-rate and sequence-of-returns math these functions follow. Four pure functions on Doubles, no dependencies beyond base.


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Versions [RSS] 0.1.0
Change log CHANGELOG.md
Dependencies base (>=4 && <5) [details]
License MIT
Copyright 2026 Poket Dev LLC
Author Poket Dev
Maintainer hello@poketdev.com
Uploaded by PoketDev at 2026-11-02T00:22:04Z
Category Math
Home page https://firenomics.com
Bug tracker https://github.com/scrapertweeter3-prog/fire-number-calc-hs/issues
Source repo head: git clone https://github.com/scrapertweeter3-prog/fire-number-calc-hs
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Downloads 3 total (3 in the last 30 days)
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Status Docs available [build log]
Last success reported on 2026-11-02 [all 1 reports]

Readme for fire-number-calc-0.1.0

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fire-number-calc

Fire number and timeline math for early retirement planning.

A fire number is annual spending divided by a withdrawal rate. The honest version of the plan also counts the gap from today's balance to that target and the years of saving it takes to close the gap when the portfolio compounds at a fixed return.

The package follows the withdrawal-rate and sequence-of-returns math published on Firenomics. It depends only on base.

Example

With $48,000 of annual spending at a 4% withdrawal rate:

  • fire number: fireNumber 48000 0.04 = $1,200,000
  • gap from a $450,000 balance: gapToTarget 450000 1200000 = $750,000
  • years to close it saving $30,000 a year at a 6% return: yearsToTarget 450000 30000 1200000 0.06 0 = 10 years
  • the same plan with the spending budget growing 3% a year until retirement: 17 years

The last two numbers are the point. A budget that grows before retirement pushes the crossing point out by seven working years in this plan, and budgetCost returns both timelines so the comparison is one call.