# How the Mortgage Payment Calculator Works

> Semi-annual compounding, the amortization schedule, payment frequencies, and the 25- versus 30-year trade.

Category: Calculator Guide
Last verified: 2026-08-02
Source: https://ratellow.com/mortgages/payment-calculator/guide

## TL;DR
- Periodic rate: i = (1 + r/2)^(1/6) − 1. That is the Canadian fixed-rate convention behind every payment on the parent tool.
- A longer amortization lowers the payment and raises lifetime interest — it is a cash-flow tool, not a savings tool.
- Worked examples and frequency comparisons live on this guide; the interactive engine stays on the parent calculator.