# Sambokoll

> Sambokoll is a Swedish household finance web app for couples ("sambos"), families and shared households: a joint budget, fair cost sharing between members, savings goals and FIRE planning, all in Swedish kronor (SEK). It also offers a free, public FIRE calculator that works without an account.

Key facts:

- Language: Swedish by default, English available with `?locale=en`.
- Currency and formats: SEK, Swedish number and date formats.
- Pricing: free at the moment. A paid subscription will most likely be introduced later, announced in advance.
- Hosting: the application and database run on servers in Sweden.
- Sign-in: passwordless magic link by email. No bank credentials are ever asked for; transactions are imported from bank export files (CSV/Excel).
- Operator: Rendly AB, Sweden. Data export as CSV, JSON or an encrypted copy.

## Pages

- [Home](https://sambokoll.se/): what Sambokoll does — budget, cost sharing (50/50, percentage, income-weighted and more), goals, benchmarks and FIRE planning.
- [Forum](https://sambokoll.se/forum): a public discussion board about household finances in Sweden — budgets, cost sharing between partners, savings and FIRE. Anyone can read; posting and replying needs a (free) account. Posts carry admin-managed tags, 50 posts per page, newest activity first.
- [FIRE calculator](https://sambokoll.se/fire-kalkylator): free, no login. Work out how many years until you are financially independent from current capital, monthly savings, annual spending today, the planned yearly withdrawal in retirement (set directly or via a lean/regular/fat lifestyle), expected real return and a target multiple (default 30×, a ~3.3 % withdrawal rate). Can also plan one or more part-time periods before full retirement (Barista FIRE) and periods of higher or lower income (a raise, leave). Includes an optional Monte Carlo simulation and an FAQ. Scenarios are shareable via query parameters, e.g. https://sambokoll.se/fire-kalkylator?portfolio=500000&savings=10000&spending=360000&return=5&multiple=30
- [Terms of service](https://sambokoll.se/legal/terms)
- [Privacy policy](https://sambokoll.se/legal/privacy)

## FIRE calculation method

- Annual withdrawal in retirement = today's annual spending × lifestyle factor (lean 0.7, regular 1.0, fat 1.3), unless an explicit withdrawal amount is given. The lifestyle never changes today's spending.
- Target portfolio = annual withdrawal × multiple. Multiple defaults to 30 (25 corresponds to the 4 % rule).
- Portfolio after t years: FV = PV·(1+r)^t + PMT·((1+r)^t − 1)/r, where PV is current capital, PMT is annual savings (12 × monthly) and r is the real (inflation-adjusted) annual return.
- Years to financial independence: the smallest t where FV ≥ target (solved to a fraction of a year); "not reachable" if that takes over 100 years.
- Safe annual withdrawal = target ÷ multiple (equal to the planned withdrawal).
- Part-time / Barista FIRE (optional): periods of part-time work given as years × working share. Pay = today's net income (spending + 12 × monthly savings) × working share; spending stays at today's level and the portfolio covers the difference (or receives the surplus). Reports the earliest point to go part-time such that the portfolio never runs out and reaches the target when the last period ends, and the resulting year of full financial independence.
- Income changes (optional): periods given as start (years from now) × length × percent change of today's net income. Spending is unchanged, so the difference is added to or taken from savings while working (part-time pay included).
- Monte Carlo (optional): 1,000 paths with normally distributed yearly returns (mean r, 15 % volatility); reports the success rate and 10th/50th/90th-percentile years.

## API

- [FIRE calculation API](https://sambokoll.se/api/fire): `GET https://sambokoll.se/api/fire?portfolio=500000&savings=10000&spending=360000&return=5&multiple=30&lifestyle=regular&monte_carlo=false` returns JSON (target portfolio, annual and monthly withdrawal, years to FI, FI year, safe withdrawal, optional Monte Carlo percentiles). No authentication, CORS enabled, read-only. All parameters are optional and default to the values shown; add `withdrawal=300000` to plan for a specific yearly withdrawal instead of the lifestyle factor, and `parttime=10x75` (comma-separated `years`x`percent`, up to 5 periods, e.g. `10x75,5x50`) to plan part-time periods before full retirement, and `income=0x5x20` (comma-separated `start`x`years`x`percent`, percent may be negative, up to 5) for periods of higher or lower net income. Amounts in SEK; `return` in percent.
- [OpenAPI description](https://sambokoll.se/api/openapi.json)

## Optional

- Everything under /app requires an account and is private household data; it is not crawlable and not available through any public API.