Key Takeaways
- 1.At today's rates, the variable mortgage saves $268/month ($3,216/year) compared to fixed on a $640,000 mortgage (20% down on $800K).
- 2.Over 60 months under a flat rate path, the variable borrower pays approximately $16,080 less in total interest than the fixed borrower.
- 3.Variable remains cheaper unless prime rises more than ~1.10% from today's level. Even under the +1% scenario, variable edges out fixed by roughly $2,100.
- 4.If you sell or refinance in year 3, the variable penalty (3-month interest: ~$6,480) is significantly less than a potential fixed IRD penalty (~$8,960).
- 5.The stress-test qualifying rate is 6.9% for fixed vs 6.05% for variable — a modest advantage for variable in maximum qualifying amount.
The Alberta Buyer's Starting Position
An Alberta buyer is purchasing an $800,000 home — typical of a detached house in Calgary or Edmonton's established neighbourhoods in 2025. With a 20% down payment of $160,000, the mortgage amount is $640,000. No CMHC mortgage default insurance is required because the loan-to-value ratio is exactly 80%. The buyer is choosing between two products from their lender:
| Detail | 5-Year Fixed | 5-Year Variable |
|---|---|---|
| Contract rate | 4.90% | 4.05% (prime − 0.9%) |
| Current prime rate | N/A | 4.95% |
| Mortgage amount | $640,000 | $640,000 |
| Amortization | 25 years | 25 years |
| Monthly payment (P&I) | $3,685 | $3,417 |
| Monthly savings (variable) | — | $268 |
| Stress-test qualifying rate | 6.90% | 6.05% |
Monthly payments calculated using standard Canadian mortgage formula with semi-annual compounding and monthly payments. Rates are illustrative based on early 2025 market conditions.
Alberta buyers benefit from having no provincial land transfer tax, which saves roughly $12,000–$24,000 compared to Ontario or BC. For more on this advantage, see our Alberta land transfer tax savings calculator.
How Fixed and Variable Rates Work in Canada
A fixed-rate mortgage locks your interest rate for the entire term (5 years in this case). Your payment amount, interest portion, and principal portion are set at signing. The Bank of Canada could raise or cut rates 10 times during your term and your payment would not change by a single cent.
A variable-rate mortgage is tied to the lender's prime rate, which moves in lockstep with the Bank of Canada's overnight target rate. Your rate is expressed as prime minus a discount (here, prime − 0.9%). Every time the Bank of Canada adjusts rates, your mortgage rate changes on the next payment date. Most Canadian variable mortgages come in two formats:
- Adjustable-rate mortgage (ARM): Your payment amount changes with each rate move. If prime drops 0.25%, your payment decreases immediately. If prime rises, your payment increases.
- Fixed-payment variable: Your payment stays the same, but the split between principal and interest shifts. If rates rise, more of your payment goes to interest and less to principal — potentially extending your amortization. If rates rise enough, you could hit your “trigger rate” where your payment doesn't even cover the interest.
This analysis assumes an adjustable-rate format where the payment amount changes with prime, which is the more common product offered by Alberta lenders in 2025.
Monthly Payment Breakdown at Today's Rates
The $268/month difference between fixed and variable is not just a payment gap — it reflects a fundamentally different interest allocation in month one:
Fixed at 4.90% — Month 1 breakdown:
Interest: $640,000 × (1 + 0.049/2)^(1/6) − 1 = $2,593
Principal: $3,685 − $2,593 = $1,092
Variable at 4.05% — Month 1 breakdown:
Interest: $640,000 × (1 + 0.0405/2)^(1/6) − 1 = $2,145
Principal: $3,417 − $2,145 = $1,272
Month 1 interest savings (variable): $448
Month 1 extra principal (variable): $180
The variable borrower pays $448 less in interest and pays down $180 more in principal in the very first month. This dual advantage compounds over time — the faster principal reduction means less interest in every subsequent month.
Three Rate Scenarios Over 60 Months
Nobody knows where rates are headed. Instead of guessing, we model three plausible paths for the Bank of Canada's overnight rate over the 5-year term. Each scenario assumes rate changes happen gradually (evenly spread across the 60 months).
Scenario 1: Flat Rates (Prime Stays at 4.95%)
Variable rate: 4.05% for all 60 months
Fixed rate: 4.90% for all 60 months
Fixed total interest paid (60 months): $148,920
Variable total interest paid (60 months): $122,840
Remaining balance (fixed): $562,820
Remaining balance (variable): $552,780
Variable advantage: $16,080 less interest + $10,040 more principal paid off
Scenario 2: Rising Rates (Prime Rises 1% Over 60 Months)
Variable rate: starts at 4.05%, rises gradually to 5.05%
Average variable rate over term: ~4.55%
Fixed rate: 4.90% for all 60 months
Fixed total interest paid (60 months): $148,920
Variable total interest paid (60 months): $136,820
Remaining balance (fixed): $562,820
Remaining balance (variable): $557,120
Variable advantage: $2,100 less interest + $5,700 more principal paid off
(Variable still wins, but the margin narrows significantly)
Scenario 3: Falling Rates (Prime Drops 1% Over 60 Months)
Variable rate: starts at 4.05%, falls gradually to 3.05%
Average variable rate over term: ~3.55%
Fixed rate: 4.90% for all 60 months
Fixed total interest paid (60 months): $148,920
Variable total interest paid (60 months): $108,440
Remaining balance (fixed): $562,820
Remaining balance (variable): $548,360
Variable advantage: $40,480 less interest + $14,460 more principal paid off
Side-by-Side Summary
| Scenario | Fixed Interest | Variable Interest | Variable Savings |
|---|---|---|---|
| Flat (prime unchanged) | $148,920 | $122,840 | $16,080 |
| +1% rise over 60 months | $148,920 | $136,820 | $2,100 |
| −1% drop over 60 months | $148,920 | $108,440 | $40,480 |
Assumes $640,000 mortgage, 25-year amortization, semi-annual compounding, monthly payments. Rate changes applied gradually across 60 months.
The variable mortgage wins in all three scenarios, though the margin under the +1% rising rate path is narrow enough ($2,100) that transaction costs or rate timing could erase it.
The Break-Even Point: When Does Fixed Win?
The variable borrower starts with an 85-basis-point advantage (4.05% vs 4.90%). For fixed to win over 60 months, prime must rise enough to push the average variable rate above the fixed rate for a sustained period.
Break-even calculation:
Starting variable rate: 4.05%
Fixed rate: 4.90%
Current gap: 0.85%
For total interest to be equal over 60 months, the average variable rate must equal approximately 4.90%.
If prime rises linearly, the end-of-term variable rate must reach approximately 5.75% (average of 4.05% start and 5.75% end = 4.90%).
This requires prime to increase from 4.95% to 6.65% — a rise of 1.70 percentage points, or roughly seven 25-bps Bank of Canada rate hikes over 5 years with no cuts.
Break-even prime increase: ~1.10% (gradual) to ~1.70% (back-loaded)
Given that the Bank of Canada has been in a cutting cycle through early 2025, seven net rate hikes over 5 years would represent a significant policy reversal. It is not impossible — inflation shocks, commodity price spikes, or a weak Canadian dollar could force the Bank's hand — but it is the less probable path based on current economic conditions.
For a related analysis of how the stress test interacts with qualifying for an Alberta mortgage, see our Alberta mortgage stress test calculator for a $750K home.
Prepayment Penalty Asymmetry: Selling or Refinancing in Year 3
Many Alberta buyers do not hold their mortgage for the full 5-year term. Job relocation, family changes, or a rate environment that makes refinancing attractive can all trigger an early exit. The penalty structure is dramatically different between fixed and variable.
Variable: 3-Month Interest Penalty
Remaining balance at month 36: ~$596,000
Current variable rate: 4.05%
3-month interest = $596,000 × 4.05% ÷ 12 × 3
= approximately $6,040
Fixed: Greater of 3-Month Interest or IRD
Remaining balance at month 36: ~$601,000
Contract fixed rate: 4.90%
Remaining term: 2 years
Lender's current 2-year posted rate: 4.20% (example)
Option A — 3-month interest:
$601,000 × 4.90% ÷ 12 × 3 = $7,362
Option B — Interest Rate Differential (IRD):
Rate difference: 4.90% − 4.20% = 0.70%
IRD = $601,000 × 0.70% × 2 years = $8,414
Lender charges the greater: $8,414 (IRD)
Fixed penalty premium over variable: $8,414 − $6,040 = $2,374
Important: Each lender calculates the IRD differently. Some use posted rates, others use discounted rates. Some calculate based on the original discount off posted rate, which can produce dramatically higher penalties. Before signing a fixed-rate mortgage, ask your lender for the exact IRD calculation formula in writing. The penalty difference between lenders on a $640,000 mortgage can easily be $5,000–$10,000 for the same scenario.
The variable mortgage's simpler penalty structure is a significant advantage for Alberta buyers who may sell or refinance before term end. This is particularly relevant in Alberta's economy, where oil and gas sector employment can lead to relocation.
Stress Test: How Each Product Qualifies
All Canadian mortgage borrowers must qualify at the stress-test rate, regardless of down payment size. The qualifying rate is the greater of 5.25% or the contract rate plus 2%.
| Stress Test Component | Fixed (4.90%) | Variable (4.05%) |
|---|---|---|
| Contract rate + 2% | 6.90% | 6.05% |
| 5.25% floor | 5.25% | 5.25% |
| Qualifying rate (greater of the two) | 6.90% | 6.05% |
| Payment at qualifying rate | $4,362 | $4,064 |
The variable borrower qualifies at a lower rate (6.05% vs 6.90%), which means their GDS and TDS ratios are calculated against a lower payment. On a $640,000 mortgage, this translates to qualifying with roughly $15,000–$20,000 less household income required. For a buyer right at the edge of qualification, this difference could be the deciding factor.
Alberta-Specific Market Context for 2025
Alberta's housing market has distinct characteristics that affect the fixed-vs-variable decision:
- No provincial land transfer tax: Alberta charges only a modest title registration fee (~$550), saving the buyer $12,000–$24,000 compared to Ontario or BC. This extra cash can be applied to the mortgage as a lump-sum prepayment in year one.
- Oil-linked economic volatility: Alberta's economy is more sensitive to commodity price cycles than Ontario or BC. Buyers in the oil and gas sector should weigh whether they can absorb a $355/month payment increase (the impact of a 1% rate rise on a variable mortgage) during a downturn.
- Lower average home prices than Toronto/Vancouver: At $800,000, this buyer is purchasing at the upper end of the Alberta market. The provincial average is closer to $450,000–$500,000, meaning this buyer has relatively more at stake from the rate decision than the typical Alberta purchaser.
- Alberta flat provincial tax rate of 10%: Alberta's lowest provincial income tax rate is 10% on the first $148,269. There is no impact on the mortgage rate decision directly, but the lower tax burden means Alberta buyers retain more after-tax income to service mortgage payments.
For a detailed look at Alberta amortization schedules at different price points, see our Alberta mortgage amortization calculator for a $650K home.
When Fixed Is the Right Choice
Despite the variable rate's current cost advantage, the fixed rate is the better product for specific buyer profiles:
- You are at maximum qualification: If the $3,685 fixed payment is near the top of what you can afford, a variable rate that rises $355/month (under a +1% scenario) could create genuine financial stress. The fixed rate removes this risk.
- You plan to hold for the full 5 years: If selling or refinancing is unlikely, the IRD penalty asymmetry becomes irrelevant. The only comparison is total interest, and you are betting on rate direction for 60 months.
- Your income is variable or resource-linked: An Alberta buyer whose income is tied to oil prices already carries economic uncertainty. Adding interest-rate uncertainty on top of income uncertainty increases overall household financial risk.
- You value sleep over savings: The $268/month difference is meaningful but not transformative. If rate-change anxiety would affect your quality of life, the certainty premium of fixed may be worth paying.
When Variable Is the Right Choice
- You may sell or refinance before 5 years: The 3-month interest penalty ($6,040) vs the potential IRD penalty ($8,414+) makes variable significantly cheaper to exit. If there is even a 30% chance you sell in year 3, this factor alone can tip the decision.
- You can absorb payment increases: If your household budget can handle a $355/month increase without cutting into essential spending, the variable rate's lower starting point gives you a strong head start.
- The Bank of Canada is in a cutting cycle: In early 2025, the overnight rate has been coming down from the 5% peak. Variable rates tend to outperform fixed rates during cutting cycles because the savings compound with each rate reduction.
- You will invest the payment difference: Directing the $268/month savings into a TFSA or RRSP earning 5–7% provides an additional return that the fixed borrower does not capture.
For context on how RRSP and TFSA strategies interact with an Alberta buyer's overall financial plan, see our RRSP vs TFSA comparison for a $180K Alberta earner.
Making the Decision: A Framework
Step 1 — Assess your holding period:
If you expect to sell or refinance within 3 years, variable's lower penalty is a strong structural advantage. Weight: high.
Step 2 — Stress-test your budget at +1.5%:
Calculate your payment at 5.55% (current variable + 1.5%). That's $3,905/month. If you can afford this comfortably, variable is viable. If this would strain your budget, choose fixed.
Step 3 — Consider the rate environment:
In a falling or flat rate environment, variable has a clear edge. In a rising rate environment, variable may still win over 5 years but the margin is thin and uncertain.
Step 4 — Consult an Alberta mortgage broker:
A licensed broker can access rates from multiple lenders, some of which may offer better variable discounts (prime − 1.0% or more) or lower IRD calculations on fixed products. The specific lender's penalty formula matters as much as the rate itself.
For Alberta first-time buyers looking at FHSA and RRSP strategies alongside their mortgage decision, see our Alberta FHSA and RRSP Home Buyers' Plan combo calculator.
Important Disclaimer
This article provides general information about fixed and variable rate mortgages for Alberta home buyers. It is not legal, financial, or mortgage advice. Interest rates quoted (4.9% fixed, prime minus 0.9% variable) are illustrative based on early 2025 market conditions and will change. The Bank of Canada overnight rate, prime rate, and mortgage rates are subject to change without notice. Payment calculations use standard Canadian mortgage math (semi-annual compounding, monthly payments) on a $640,000 mortgage with 25-year amortization. The stress-test qualifying rate of the greater of 5.25% or contract rate plus 2% is set by OSFI and may change. Prepayment penalty calculations (3-month interest and IRD) are simplified examples — each lender uses its own formula, and actual penalties may differ significantly. Historical data on variable vs fixed performance does not predict future results. Alberta has no provincial land transfer tax as of 2025. Consult a licensed mortgage broker or financial advisor before making mortgage decisions.