Cash in, then cash back
Cash in is the purchase price, the rehab, buying closing costs, and a lump sum for costs while you renovate. The new loan is the after-repair value times the LTV you enter. LTV is capped at 100% of ARV inside the formula. Refinance proceeds are that loan minus refinance closing costs.
Cash left in the deal is cash in minus proceeds. A positive number is money you have not pulled out. A negative number is cash back: the refinance paid you more than the project cost. That is the BRRRR outcome people hope for, and it still depends on a refinance that actually funds.
Post-refinance cash flow uses the rental formulas from the DSCR calculator, with the new loan as the balance. Vacancy, taxes, insurance, HOA, and the monthly reserve all count. The purchase loan is assumed to be paid off by the refinance.
What this page will not pretend
It does not model seasoning, a prepayment penalty, or whether anyone will lend at the LTV and rate you typed. If you do not know the ARV yet, build one in the ARV estimator and then come back with a number you can defend. If you plan to sell instead of refinance, the flip calculator is the other path.