# How the Mortgage Renewal Calculator Works

> Balance at maturity, remaining amortization, payment shock, the stay-switch-refinance decision, and the 180-day renewal timeline.

Category: Calculator Guide
Last verified: 2026-08-29
Source: https://ratellow.com/mortgages/renewal-calculator/guide

## TL;DR
- A renewal is not a new mortgage. The calculator derives balance at maturity and remaining amortization, then re-prices that balance.
- Canadian fixed-rate payments use semi-annual compounding.
- Changing loan amount, remaining amortization, or payment schedule turns a straight switch into a refinance — full MQR applies.
- The 180 / 120 / 90 / 45 / 21-day timeline is on this page; the live tool stays on the parent calculator URL.