How the Mortgage Calculator Builds the Full Payment
AnyTool Mortgage Calculator assembles a complete PITI monthly payment in the browser. It first derives the loan amount as home price minus down payment, then computes the principal-and-interest portion with the standard reducing-balance formula P × r × (1 + r)ⁿ ÷ ((1 + r)ⁿ − 1), where r is the monthly rate and n the term in months, reusing the same unit-tested loan engine as the EMI tool. On top of P&I it adds escrowed costs — annual property tax ÷ 12, annual homeowners insurance ÷ 12, monthly HOA dues — and private mortgage insurance ÷ 12 when applicable. The headline figure is the sum of all five components, shown with a stacked breakdown bar.
- Loan amount = home price − down payment
- P&I via reducing-balance EMI = P × r × (1 + r)ⁿ ÷ ((1 + r)ⁿ − 1)
- Monthly = P&I + tax ÷ 12 + insurance ÷ 12 + PMI ÷ 12 + HOA
- Down payment and property tax accept a dollar amount or a percent
- All math is client-side JavaScript — no server round-trip
