# 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.
- [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). 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).
- 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. 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.