budget-tools/fire at main · karmanyaahm/budget-tools

fire: a day-by-day FIRE simulator How many years at a big salary before you can coast, retire, or retire and never shrink your nest egg. Heads up: this is a vibe-coded FIRE tool. It was built in a conversation with Claude (an AI): someone described what they wanted, and Claude wrote the code, the tests and the design log. No financial professional has reviewed it. It is not financial advice. Use it to explore ideas, and check anything important with a real human who does this for a living. What is this? It answers one question: how long do I need to work at a high salary before I can stop, coast, or retire? To find out, it simulates your money day by day to age 112 in real (today's) dollars. Each day, wages arrive net of income tax, the day's expenses go out, and any surplus is invested. When there's a shortfall, it sells from the portfolio and pays the tax on that sale. Every expense is padded by a safety factor (1.1×). A bisection solver then finds the shortest stretch at the high salary (the X in your income plan) that keeps the balance at or above $0 on every single day. Each plan is solved for three goals: retire to $0 (the money lasts until 112), coast until 60 (a job that pays your core expenses until 60), and flat from 100 (the portfolio never shrinks after 100). What you get out: For each goal, the stop age (to the day) and the portfolio at that age. An income-plan table (every salary segment, gross and after tax) and terminal charts (net worth, expenses by category, cash flow). What-if tables: how many weeks sooner you could stop if you saved an extra $A at age Y. Moving cities: live in one city's plan until an age, then another's; expenses and taxes switch at that age (plan.move_to(other, at_age); example sf_to_austin: earn in SF, move to Austin at 35). Grid sweeps across plans, income ladders, partner incomes, tax setups and account types, in one table. 401(k) + Roth + 529 accounts, on by default; the summary also shows the answer without them (--no-accounts turns them off). What it looks like uv run fire.py --plan sf_family (a shipped example: SF, one kid, a 120 → 175 → 230k ladder): What-if table and cash flow Regenerate these with uv run docs/screenshots.py (it only uses the shipped example plans). Using it with Claude Code The plans are plain Python, so Claude Code works well as the interface. Describe your life in plain English ("I make $180k, want two kids in my early 30s, might move somewhere cheaper at 35; when can I coast?") and have it write the plan in custom_plans/, run fire.py / grid.py, and put the results side by side. It's also good for questions like "what if my partner stops working?" or "does insurance really double for a couple?", for sanity-checking expense estimates, and for keeping a log of the assumptions you chose. Keep personal numbers in custom_plans/ (gitignored) so they stay out of the repo. Quickstart Requires uv. Dependencies are just rich and plotext. uv sync # install uv run fire.py --list # plans and grids you can run uv run fire.py --plan sf_family # solve every goal: summary, what-ifs, charts uv run fire.py --plan sf_family --no-plot --no-whatif # summary and income plans only (about 1 s) uv run fire.py --plan austin_family --budget # print every expense line and exit uv run fire.py --plan sf_to_austin # SF until 35, then Austin prices and Texas taxes uv run grid.py grid_cities # sweep SF/Austin × ladders × partners × accounts Main fire.py flags (--help for all). uv run grid.py [NAME] runs a grid (default DEFAULT_GRID). Flag What it does --plan NAME, -p Which plan to run (default: DEFAULT_PLAN) --no-accounts Taxable brokerage only: no 401(k) / Roth / 529 (config.NO_ACCOUNTS) --budget, -b Print every expense line ($/mo, $/yr) and exit --compare-taxes Solve under each TAX_VARIANTS entry and compare --whatif A@AGE, -w How much sooner if you save an extra $A at AGE (repeatable) --x N Skip solving: simulate this one X and print the year-by-year table --sweep Also show the whole-year X sweep table and chart -s NAME Only run goals whose name contains NAME (repeatable) --table, -t Print the year-by-year table for each solution --no-plot / --no-whatif Skip the charts / the what-if grid Make it yours default_plans/ holds the shipped examples. Your own plans go in custom_plans/, which is gitignored, is searched first, and wins over a same-name default. mkdir -p custom_plans cp default_plans/sf_family.py custom_plans/my_plan.py # then edit the numbers cat > custom_plans/__init__.py <<'EOF' DEFAULT_PLAN = "my_plan" DEFAULT_GRID = "my_grid" EOF custom_plans/ needs that __init__.py to be found. After that, a bare uv run fire.py runs your plan. A grid (e.g. custom_plans/my_grid.py) is a module with a GRID dict of axes, each {label: value}.

Per year while at the career job, before the ×1.1 safety factor: Category Main lines Age 25 Age 35 (kid is 2) housing rent $1,900/mo, utilities, internet, renters insurance $24,900 $24,900 kids + term life daycare $2,250/mo, extra bedroom $1,800/mo, baby costs, coverage – $59,340 food groceries $90/wk, eating out $70/wk $8,320 $8,320 travel trips $600/mo $7,200 $7,200 health employer plan, dental + vision, gym $3,600 $3,600 everything else social $60/wk, tech, clothes, gifts, phone, personal care, ... $8,900 $8,900 transport transit + rideshare $180/mo, bike $2,560 $2,560 Total $55,480 $114,820 Other lines switch on later: an individual health plan from RETIRE to 65 (stepping up at 50 and 58), weekday groceries once the office stops feeding you, Medicare at 65, late-life care $3,000/mo from 88, UC at $45k/yr. austin_family reuses all of this and overrides only the lines in its AUSTIN dict (rent $950, daycare $1,650, UT Austin instead of UC, cheaper health insurance, ...). It adds paid preschool at 4 (no free TK in Texas) and extra rideshare with kids, and uses TX, MFJ after wedding. That's about $45k/yr at 25.