## Formulas (BrrrCalculator.java)
- Acquisition loan = price × loan% (+ repair budget if financed)
- Holding interest = interest-only on the average balance (repair draws counted at 50%) × months
- Total cash invested = down payment + closing + repair paid in cash + loan fees + holding interest + holding costs
- New loan = ARV × LTV; Cash-out = new loan − payoff − refinance costs
- Cash left in deal = total invested − cash-out (≤ 0 → infinite cash-on-cash)
- Effective income = (rent + other) × (1 − vacancy); management on effective income; maintenance & CapEx on gross rent
- NOI = (effective income − operating expenses) × 12; Cash flow = effective income − opex − P&I
- Cap rate = NOI / ARV; DSCR = NOI / annual debt service (warning below 1.20)
- 70% rule: max offer = ARV × 0.70 − repair; 1% rule: rent / all-in cost ≥ 1%