Mamble Calculators

Educational debt service coverage ratio from user-entered rent, vacancy, operating expenses, and financing. Modeled DSCR = annual NOI ÷ annual P&I debt service (debtServiceBasis: pi). Returns NOI, debt service, debt yield, and break-even occupancy context. Not loan approval, lender underwriting, or investment advice.

calculate_dscr

Calculates front-end (housing-only) and back-end (all-debt) debt-to-income ratios given gross monthly income and monthly debt obligations. Returns whether the borrower likely qualifies for conventional financing (back-end DTI ≤ 43%) and remaining monthly debt capacity. Use when a user wants to know their DTI, whether they qualify, or how much additional debt they can take on.

calculate_dti

Analyses how monthly and one-time extra principal payments affect a fixed-rate mortgage. Returns interest saved, months and years saved, illustrative payoff dates, and effective interest reduction versus the baseline schedule. Use when a user asks about paying off a mortgage early, extra payments, prepayment impact, or mortgage prepayment vs investing (educational only).

analyze_extra_payments

Compares FHA (program A) and conventional (program B) loans on the same property and down payment. Returns monthly loan payments, total monthly housing (with tax/insurance), upfront cash, and estimated loan cost over the user's expected ownership years. FHA UFMIP and annual MIP rates and conventional PMI rate are user assumptions — not live lender pricing or an approval decision. Identifies lower monthly loan payment and lower loan cost over ownership; optional break-even ownership years when cumulative loan costs intersect.

compare_fha_vs_conventional

Compares two mortgage loan options (Loan A vs Loan B) on the same property. Returns monthly payment, total interest, upfront costs, and total lifetime cost for each loan, plus the difference in monthly payment, upfront cost, and lifetime cost between them. Identifies which loan has the lower lifetime cost. Supports comparing different rates, terms, points, and closing costs. Use when a user has two loan offers and wants to know which is better.

compare_loans

Calculates the full monthly mortgage payment breakdown including principal & interest, property tax, homeowners insurance, PMI, and HOA fees. Also returns total interest paid over the loan term. Use when a user wants to know their expected monthly housing cost, how down payment affects payment, or the total cost of a loan. Set includeSchedule=true to receive the full month-by-month amortization schedule.

calculate_mortgage_payment

Calculates monthly PMI cost, LTV ratio, and the estimated month/year when PMI can be removed (accounting for principal paydown and home appreciation). Returns total PMI cost until removal and the payment difference with vs. without PMI. Use when a user wants to know their PMI cost, when they can cancel PMI, or whether to make a larger down payment to avoid PMI entirely.

calculate_pmi

Estimates a potential prepayment penalty from user-entered balance, prepayment amount, and penalty terms (none, percent of prepayment, percent of balance, months of interest, or flat fee). Returns separated remaining balance, prepayment, penalty, and estimated cash required to prepay. Optional comparison only when comparisonMode is set with user-supplied savings. Educational only — not legal interpretation.

calculate_prepayment_penalty

Educational modeled total return for a rental property over a user-chosen horizon. Combines cumulative modeled cash flow and projected equity at sale (from appreciation assumptions you enter). Returns modeled total return %, cash-on-cash (year-one), annual cash flow, equity at horizon, and projection rows. Not IRR/XIRR, not tax-adjusted, not investment advice or live market data.

analyze_roi

Educational refinance break-even: months to recover user-entered closing costs (and optional prepayment penalty) through modeled monthly P&I savings (monthlySavingsBasis: pi_only). Returns adjusted break-even, payment comparison, and modeled interest/cost differences. Not loan approval, live rates, or tax advice.

analyze_break_even

Analyses a mortgage refinance scenario by comparing the current loan against a proposed refinance. Returns monthly savings, break-even period (months/years to recover closing costs), total lifetime cost comparison, and a simple should-refinance heuristic. Supports rate-and-term and cash-out refinances. Use when a user asks "should I refinance?", wants to compare their current rate to a new offer, or wants to know the break-even point on closing costs.

analyze_refinance