Mortgage Calculator Methodology
All calculators use the same tested engine and the versioned rules listed below.
Payments
Fixed-rate payments use semi-annual compounding: the periodic rate is (1 + j/2)^(2/k) − 1 for an annual rate j and k payments a year, and the payment is P·i / (1 − (1 + i)^−n). Accelerated bi-weekly and weekly payments are half and a quarter of the monthly payment.
Qualification
The qualifying rate is the higher of the contract rate plus 2 points or 5.25%. GDS uses the payment at the qualifying rate plus property tax, heating and half of condo fees; TDS adds other debts.
Insurance
Premiums use CMHC's homeowner rates by loan-to-value. Provincial sales tax on the premium is treated as a cash closing cost.
Rules in use
| Rule | Version | In effect from | Status | Official source |
|---|---|---|---|---|
| fcac.min_down_payment | v2 | 2024-12-15 | Active | FCAC |
| osfi.fcac.minimum_qualifying_rate | v1 | 2021-06-01 | Active | FCAC / OSFI |
| fcac.debt_service_ratios | v1 | 2021-06-01 | Active | FCAC |
| cmhc.homeowner_premiums | v2 | 2024-12-15 | Active | CMHC |
| fcac.max_amortization | v1 | 2024-12-15 | Active | FCAC |
| cra.fhsa_limits | v1 | 2023-04-01 | Active | CRA |
| cra.home_buyers_plan | v2 | 2024-04-16 | Active | CRA |
| fcac.renewal_statement_notice | v1 | 2010-01-01 | Active | FCAC |
| fcac.heloc_limits | v1 | 2012-07-09 | Active | FCAC |
| fcac.prepayment_privileges | v1 | 2010-01-01 | Active | FCAC |
| cmhc.closing_cost_items | v1 | 2026-11-12 | Active | CMHC |
| cmhc.affordability_standard | v1 | 2026-11-12 | Active | CMHC |
| cra.gst_new_housing_rebate | v1 | 2008-01-01 | Active | Excise Tax Act, s. 254(2); CRA guide RC4028 |
| cra.fthb_gst_rebate | v1 | 2025-03-20 | Active | Excise Tax Act, s. 254(2.1); CRA guide RC4028 |
| cra.home_buyers_amount | v1 | 2022-01-01 | Active | CRA (line 31270) |
| fcac.prepayment_penalty | v1 | 2026-11-12 | Active | FCAC |
| fcac.blend_and_extend | v1 | 2026-11-12 | Active | FCAC |
| on.land_transfer_tax | v1 | 2017-01-01 | Active | Ontario Ministry of Finance |
| toronto.municipal_land_transfer_tax | v1 | 2026-04-01 | Active | City of Toronto |
| bc.property_transfer_tax | v1 | 2024-04-01 | Active | Government of British Columbia |
| mb.land_transfer_tax | v1 | 2020-01-01 | Active | Government of Manitoba (C.C.S.M. c. T2, s. 112) |
| nb.real_property_transfer_tax | v1 | 2016-04-01 | Active | Government of New Brunswick (Real Property Transfer Tax Act, s. 2(1.03)) |
| pe.real_property_transfer_tax | v1 | 2005-01-01 | Active | Government of Prince Edward Island (Real Property Transfer Tax Act) |
| nl.registration_of_deeds_fees | v1 | 2007-04-26 | Active | Government of Newfoundland and Labrador, Registry of Deeds |
| ab.land_titles_fees | v1 | 2026-10-01 | Active | Government of Alberta, Land Titles |
| sk.land_titles_fees | v1 | 2026-04-15 | Active | Information Services Corporation (Saskatchewan Land Registry) |
Sources
Rules are summarized in our own words from official publications. Check the source and talk to your lender or a licensed professional before making a decision.
Informational only, not financial advice. Data as of the release snapshot generated 2026-11-12.