Validation report
Mortgage Calculator Validation Report
A permanent test report for the usecos.app Canadian mortgage calculator covering payment math, CMHC premium estimates, stress-test payment math, and provincial land-transfer tax outputs.
Verified on 2026-07-29. These are calculator-validation scenarios, not lender quotes.
Direct answer
Across 50 published test cases, 50 passed. The largest pre-rounding payment difference between usecos.app and the independent Canadian mortgage formula is $0.00. CMHC premium, stress-test payment, and land-transfer tax differences are also shown below.
Payment max diff
$0.00
CMHC max diff
$0.00
Stress max diff
$0.00
LTT max diff
$0.00
Published validation cases
| Case | Price | Down | Rate | Freq | usecos.app | Independent | Diff | Pass |
|---|---|---|---|---|---|---|---|---|
| M-01 | $325,000.00 | $16,250.00 | 3.95% | monthly | $1,667.82 | $1,667.82 | $0.00 | Pass |
| M-02 | $350,000.00 | $35,000.00 | 4.30% | biweekly | $813.03 | $813.03 | $0.00 | Pass |
| M-03 | $375,000.00 | $56,250.00 | 4.65% | weekly | $424.85 | $424.85 | $0.00 | Pass |
| M-04 | $400,000.00 | $80,000.00 | 5.00% | biweekly_acc | $930.57 | $930.57 | $0.00 | Pass |
| M-05 | $425,000.00 | $106,250.00 | 5.35% | weekly_acc | $538.81 | $538.81 | $0.00 | Pass |
| M-06 | $450,000.00 | $22,500.00 | 5.70% | monthly | $2,765.78 | $2,765.78 | $0.00 | Pass |
| M-07 | $475,000.00 | $47,500.00 | 6.05% | biweekly | $1,216.38 | $1,216.38 | $0.00 | Pass |
| M-08 | $500,000.00 | $75,000.00 | 3.95% | weekly | $527.62 | $527.62 | $0.00 | Pass |
| M-09 | $525,000.00 | $105,000.00 | 4.30% | biweekly_acc | $1,376.73 | $1,376.73 | $0.00 | Pass |
| M-10 | $550,000.00 | $137,500.00 | 4.65% | weekly_acc | $579.40 | $579.40 | $0.00 | Pass |
| M-11 | $575,000.00 | $28,750.00 | 5.00% | monthly | $3,304.10 | $3,304.10 | $0.00 | Pass |
| M-12 | $600,000.00 | $60,000.00 | 5.35% | biweekly | $1,546.08 | $1,546.08 | $0.00 | Pass |
| M-13 | $625,000.00 | $93,750.00 | 5.70% | weekly | $726.17 | $726.17 | $0.00 | Pass |
| M-14 | $650,000.00 | $130,000.00 | 6.05% | biweekly_acc | $1,671.23 | $1,671.23 | $0.00 | Pass |
| M-15 | $675,000.00 | $168,750.00 | 3.95% | weekly_acc | $662.32 | $662.32 | $0.00 | Pass |
| M-16 | $700,000.00 | $35,000.00 | 4.30% | monthly | $3,751.30 | $3,751.30 | $0.00 | Pass |
| M-17 | $725,000.00 | $72,500.00 | 4.65% | biweekly | $2,051.28 | $2,051.28 | $0.00 | Pass |
| M-18 | $750,000.00 | $112,500.00 | 5.00% | weekly | $879.59 | $879.59 | $0.00 | Pass |
| M-19 | $775,000.00 | $155,000.00 | 5.35% | biweekly_acc | $1,719.78 | $1,719.78 | $0.00 | Pass |
| M-20 | $800,000.00 | $200,000.00 | 5.70% | weekly_acc | $933.13 | $933.13 | $0.00 | Pass |
| M-21 | $825,000.00 | $41,250.00 | 6.05% | monthly | $5,827.94 | $5,827.94 | $0.00 | Pass |
| M-22 | $850,000.00 | $85,000.00 | 3.95% | biweekly | $1,904.98 | $1,904.98 | $0.00 | Pass |
| M-23 | $875,000.00 | $131,250.00 | 4.30% | weekly | $957.03 | $957.03 | $0.00 | Pass |
| M-24 | $900,000.00 | $180,000.00 | 4.65% | biweekly_acc | $2,022.63 | $2,022.63 | $0.00 | Pass |
| M-25 | $925,000.00 | $231,250.00 | 5.00% | weekly_acc | $963.12 | $963.12 | $0.00 | Pass |
| M-26 | $950,000.00 | $47,500.00 | 5.35% | monthly | $5,647.45 | $5,647.45 | $0.00 | Pass |
| M-27 | $975,000.00 | $97,500.00 | 5.70% | biweekly | $2,597.54 | $2,597.54 | $0.00 | Pass |
| M-28 | $1,000,000.00 | $150,000.00 | 6.05% | weekly | $1,296.14 | $1,296.14 | $0.00 | Pass |
| M-29 | $1,025,000.00 | $205,000.00 | 3.95% | biweekly_acc | $2,466.81 | $2,466.81 | $0.00 | Pass |
| M-30 | $1,050,000.00 | $262,500.00 | 4.30% | weekly_acc | $1,067.87 | $1,067.87 | $0.00 | Pass |
| M-31 | $1,075,000.00 | $53,750.00 | 4.65% | monthly | $5,448.34 | $5,448.34 | $0.00 | Pass |
| M-32 | $1,100,000.00 | $110,000.00 | 5.00% | biweekly | $2,739.87 | $2,739.87 | $0.00 | Pass |
| M-33 | $1,125,000.00 | $168,750.00 | 5.35% | weekly | $1,568.49 | $1,568.49 | $0.00 | Pass |
| M-34 | $1,150,000.00 | $230,000.00 | 5.70% | biweekly_acc | $2,861.58 | $2,861.58 | $0.00 | Pass |
| M-35 | $1,175,000.00 | $293,750.00 | 6.05% | weekly_acc | $1,416.13 | $1,416.13 | $0.00 | Pass |
| M-36 | $1,200,000.00 | $60,000.00 | 3.95% | monthly | $6,204.40 | $6,204.40 | $0.00 | Pass |
| M-37 | $1,225,000.00 | $122,500.00 | 4.30% | biweekly | $2,584.50 | $2,584.50 | $0.00 | Pass |
| M-38 | $1,250,000.00 | $187,500.00 | 4.65% | weekly | $1,416.17 | $1,416.17 | $0.00 | Pass |
| M-39 | $1,275,000.00 | $255,000.00 | 5.00% | biweekly_acc | $2,966.19 | $2,966.19 | $0.00 | Pass |
| M-40 | $1,300,000.00 | $325,000.00 | 5.35% | weekly_acc | $1,466.62 | $1,466.62 | $0.00 | Pass |
| M-41 | $1,325,000.00 | $66,250.00 | 5.70% | monthly | $9,254.10 | $9,254.10 | $0.00 | Pass |
| M-42 | $1,350,000.00 | $135,000.00 | 6.05% | biweekly | $3,716.26 | $3,716.26 | $0.00 | Pass |
| M-43 | $1,375,000.00 | $206,250.00 | 3.95% | weekly | $1,310.61 | $1,310.61 | $0.00 | Pass |
| M-44 | $1,400,000.00 | $280,000.00 | 4.30% | biweekly_acc | $3,037.49 | $3,037.49 | $0.00 | Pass |
| M-45 | $1,425,000.00 | $356,250.00 | 4.65% | weekly_acc | $1,705.63 | $1,705.63 | $0.00 | Pass |
| M-46 | $1,450,000.00 | $72,500.00 | 5.00% | monthly | $8,332.07 | $8,332.07 | $0.00 | Pass |
| M-47 | $1,475,000.00 | $147,500.00 | 5.35% | biweekly | $3,800.78 | $3,800.78 | $0.00 | Pass |
| M-48 | $1,500,000.00 | $225,000.00 | 5.70% | weekly | $1,830.36 | $1,830.36 | $0.00 | Pass |
| M-49 | $1,525,000.00 | $305,000.00 | 6.05% | biweekly_acc | $3,722.51 | $3,722.51 | $0.00 | Pass |
| M-50 | $1,550,000.00 | $387,500.00 | 3.95% | weekly_acc | $1,520.88 | $1,520.88 | $0.00 | Pass |
Formula and test code
The independent payment formula converts the Canadian semi-annual quoted rate to an effective monthly rate, then applies the standard amortizing-payment formula:
monthlyRate = (1 + annualRate / 100 / 2)^(2 / 12) - 1 payment = loan * monthlyRate / (1 - (1 + monthlyRate)^(-months))
Test-case generation and independent comparison code lives in lib/mortgage-validation-report.ts. The regression suite verifies every row stays within one cent for payment, CMHC premium, stress-test payment, and land-transfer tax.
Sources and verification
Verified July 29, 2026. The validation compares formulas and published test cases; it does not guarantee lender approval, exact closing costs, or eligibility for insured mortgage programs.