Key Takeaways
- 1.The 5-year fixed at 4.99% costs $3,794/month. The variable starts at $3,670/month (prime 5.45% minus 0.75% = 4.70%) and drops to $3,375/month if prime reaches 4.50%.
- 2.Total 5-year interest: $147,400 fixed vs an estimated $128,700 variable under the projected rate path — a $18,700 saving on the variable.
- 3.The break-even point is ~14 months. Before that, the fixed rate is cheaper because the variable starts below its full discount. After month 14, cumulative variable savings overtake the fixed.
- 4.Breaking a fixed-rate mortgage after 2 years triggers an IRD penalty of approximately $14,350. The variable penalty is only ~$7,481 (three months' interest).
- 5.Over a full 25-year amortization, the interest gap widens to $34,800–$117,800 depending on the long-term average variable rate.
The Setup: Two Rate Scenarios on One Mortgage
Both scenarios use identical loan parameters. The only variable is the interest rate path.
Mortgage amount: $650,000
Amortization: 25 years (300 months)
Payment frequency: Monthly
Term: 5 years
Scenario A — Fixed: 4.99% for full 5-year term
Scenario B — Variable: Prime minus 0.75%
Months 1–6: Prime 5.45% → variable rate 4.70%
Months 7–12: Prime 4.95% → variable rate 4.20%
Months 13–60: Prime 4.50% → variable rate 3.75%
The rate path for Scenario B reflects consensus forecasts as of early 2025: the Bank of Canada cutting 50 basis points by mid-2025 and another 45 basis points by the end of 2025, then holding steady. This is a projection, not a guarantee. If the Bank of Canada cuts less aggressively, the variable savings shrink. If it cuts more, they grow.
Monthly Payment Comparison
The monthly payment is the number most borrowers feel first. Here is what each scenario looks like at each rate stage:
| Period | Fixed (4.99%) | Variable Rate | Variable Payment | Monthly Delta |
|---|---|---|---|---|
| Months 1–6 | $3,794 | 4.70% | $3,670 | -$124 |
| Months 7–12 | $3,794 | 4.20% | $3,461 | -$333 |
| Months 13–60 | $3,794 | 3.75% | $3,375 | -$419 |
Variable payments assume the lender adjusts the payment amount with each prime rate change. Some lenders hold the payment constant and adjust the principal/interest split instead — in that case, more of each payment goes to principal when rates drop, achieving a similar total-cost result.
By month 13, the variable-rate borrower is paying $419 less per month than the fixed-rate borrower. Over the remaining 48 months of the term, that adds up to $20,112 in payment savings alone. Even accounting for the first 12 months where the gap is narrower, the cumulative payment difference is substantial.
Total Interest Paid: 5-Year Term
Monthly payments include both principal and interest. The real cost comparison is total interest paid over the 5-year term, because principal payments are equity you keep.
| Metric | Fixed (4.99%) | Variable (Projected) | Difference |
|---|---|---|---|
| Total payments (60 months) | $227,640 | $206,490 | -$21,150 |
| Total interest paid | $147,400 | $128,700 | -$18,700 |
| Principal repaid | $80,240 | $77,790 | -$2,450 |
| Balance at renewal | $569,760 | $572,210 | +$2,450 |
The variable scenario pays slightly less principal because the lower payment in months 7–60 directs a smaller dollar amount to principal. However, the $18,700 interest saving far outweighs the $2,450 difference in principal repayment. If you redirect the variable's monthly savings into extra principal payments, you repay more principal and save on interest.
The $18,700 gap is the headline number. Under the projected rate path, a $650K variable-rate mortgage saves the Ontario couple roughly $18,700 in interest over five years compared to the fixed alternative. That is real money — enough to cover Ontario land transfer tax on a move-up purchase. For a breakdown of Ontario land transfer tax at various price points, see our Ontario land transfer tax calculator.
The Break-Even Point: When Does Variable Win?
The variable rate starts lower than the fixed rate in this scenario (4.70% vs 4.99%), so it is ahead from day one. But the real question is when cumulative savings become large enough to justify the risk. Here is the month-by-month cumulative interest comparison:
| Month | Fixed Cumul. Interest | Variable Cumul. Interest | Variable Advantage |
|---|---|---|---|
| 6 | $16,030 | $15,090 | +$940 |
| 12 | $31,830 | $28,510 | +$3,320 |
| 24 | $62,680 | $52,460 | +$10,220 |
| 36 | $92,520 | $75,850 | +$16,670 |
| 60 | $147,400 | $128,700 | +$18,700 |
Because the variable rate is lower than fixed from month 1 in this scenario, the variable is ahead from the start. The advantage accelerates after month 6 when prime drops further. The “break-even” in a scenario where variable starts higher than fixed would occur later — typically 14–18 months with a 0.50% starting premium.
If you are considering a scenario where the variable starts above the fixed — for example, prime at 6.20% minus 0.75% = 5.45% vs a 4.99% fixed — the break-even occurs approximately 14 months into the term, assuming prime drops to 4.50% by month 12. Before month 14, the fixed-rate borrower has paid less cumulative interest. After month 14, the variable pulls ahead and the gap widens every month.
Penalty Math: What It Costs to Break Early
Life changes — job relocation, divorce, upsizing for a growing family. If you break your mortgage before the term ends, the penalty structure is dramatically different between fixed and variable.
| Penalty Component | Fixed (4.99%) | Variable (4.70%) |
|---|---|---|
| Penalty type | Greater of IRD or 3 months' interest | 3 months' interest only |
| Balance at break (after 2 years) | $621,000 | $623,400 |
| 3 months' interest | $7,940 | $7,481 |
| IRD calculation | $14,350 | N/A |
| Actual penalty | $14,350 | $7,481 |
IRD example: contracted rate 4.99% minus current 3-year posted rate 4.25% = 0.74% differential. $621,000 × 0.74% × (36 remaining months ÷ 12) = $14,350. The exact IRD formula varies by lender — big banks use posted rates (higher penalty), while monolines and credit unions often use discounted rates (lower penalty). Always confirm the calculation method before signing.
The penalty difference is $6,869 — nearly the cost of a year's property tax in many Ontario municipalities. If there is any chance you will sell, refinance, or renegotiate before the term ends, the variable rate's simpler penalty structure is a significant advantage.
The Psychological Cost of Payment Volatility
Spreadsheets say variable wins. Your stress response may disagree. Variable-rate borrowers live with uncertainty: every Bank of Canada rate announcement is a potential change to your household budget. On a $650K mortgage, a single 0.25% rate hike adds roughly $95 to your monthly payment. Two consecutive hikes add $190.
The real risk is not the rate itself — it is your behavioral response. Variable-rate borrowers who panic during rate hikes and lock in to a fixed rate mid-term often do so at the worst possible time, near the top of the rate cycle. They pay the conversion spread plus a higher fixed rate, effectively getting the worst of both worlds.
Ask yourself these questions before choosing variable:
- Can your household absorb a $400/month payment increase without cutting essentials?
- Would you check mortgage rates weekly, or are you comfortable ignoring rate news?
- Have you held a variable-rate product before and stayed the course through a rate hike cycle?
- Is this mortgage within your stress-test qualification, with room to spare?
If you answered “no” to two or more, the fixed rate's premium is worth paying for the certainty. The $18,700 variable saving means nothing if you lock in at 5.5% after a panic at month 18.
For context on how the mortgage stress test works and what rate you need to qualify at, see our mortgage stress test calculator.
25-Year Amortization: Full Lifecycle Comparison
The 5-year term is when you make the fixed-vs-variable decision. But the mortgage lives for 25 years. Here is what the full amortization looks like under three constant-rate assumptions:
| Scenario | Rate | Monthly Payment | Total Interest (25 yr) | Total Cost |
|---|---|---|---|---|
| Fixed at 4.99% | 4.99% | $3,794 | $507,300 | $1,157,300 |
| Variable avg 4.70% | 4.70% | $3,670 | $472,500 | $1,122,500 |
| Variable avg 4.00% | 4.00% | $3,377 | $389,500 | $1,039,500 |
Constant-rate scenarios are illustrative. In reality, you renegotiate the rate every 5 years at renewal. The 25-year figures show the compounding impact of rate differences over the full amortization. A 1% average rate reduction saves approximately $117,800 in interest over 25 years on a $650K mortgage.
The 25-year view makes the stakes clearer. Over the life of a $650K mortgage, the difference between a 4.99% average and a 4.00% average is $117,800. That is a significant portion of the original purchase price. Even a modest 0.29% average reduction (4.99% vs 4.70%) saves $34,800 over 25 years.
What Happens If Rates Go Up Instead?
The projections above assume the Bank of Canada follows through on rate cuts. What if inflation reignites, tariff uncertainty persists, or external shocks force rates higher?
| Rate Scenario | Variable 5-Year Interest | Fixed 5-Year Interest | Variable vs Fixed |
|---|---|---|---|
| Prime drops to 4.00% | $115,200 | $147,400 | Saves $32,200 |
| Prime drops to 4.50% (base case) | $128,700 | $147,400 | Saves $18,700 |
| Prime stays at 5.45% | $141,800 | $147,400 | Saves $5,600 |
| Prime rises to 6.00% | $157,300 | $147,400 | Costs $9,900 more |
| Prime rises to 6.70% | $172,400 | $147,400 | Costs $25,000 more |
Note that even with prime unchanged at 5.45%, the variable still saves money because the variable rate (4.70%) is below the fixed rate (4.99%) due to the prime-minus-0.75% discount. The variable only loses if prime rises above 5.74% (where variable rate = 4.99% = fixed rate) and stays there.
The asymmetry matters. In the best case (prime to 4.00%), the variable saves $32,200. In the worst realistic case (prime to 6.70%), the variable costs $25,000 more. The downside is smaller than the upside, and the probability-weighted outcome favours variable when rate cuts are more likely than hikes. But the downside is not zero — and for a household where an extra $300/month would cause genuine hardship, the fixed rate is rational insurance.
Ontario-Specific Considerations
The mortgage math is the same across Canada, but Ontario homebuyers face additional cost layers that interact with the fixed-vs-variable decision:
Ontario land transfer tax: On a home priced to produce a $650K mortgage (approximately $810K purchase with 20% down), Ontario LTT is approximately $12,475. Toronto buyers pay a second municipal LTT of equal amount. For exact calculations at your price point, see our Ontario land transfer tax calculator.
Stress test qualification: Both fixed and variable borrowers must qualify at the higher of 5.25% or contract rate + 2%. At 4.99% fixed, you qualify at 6.99%. At 4.70% variable, you qualify at 6.70%. The variable borrower technically qualifies at a slightly lower stress-test rate, which can marginally increase maximum purchase power.
RRSP Home Buyers' Plan: If either partner is a first-time buyer, you can withdraw up to $60,000 each from RRSPs for the down payment. This is relevant for couples stretching to reach 20% down on a higher-priced Ontario home. For more on how RRSP contributions interact with your overall tax strategy, see our RRSP vs TFSA comparison.
How to Decide: A Practical Framework
Choose fixed (4.99%) if:
- Your total housing costs (mortgage + property tax + condo fees) exceed 35% of gross income
- You have no emergency fund beyond 2 months of expenses
- You plan to stay in the home for the full 5-year term with high certainty
- Payment certainty is more valuable to you than probable savings
Choose variable (prime − 0.75%) if:
- You can absorb a $400–$500/month payment increase without lifestyle changes
- You want the lower penalty in case you sell or refinance before term end
- You believe rate cuts are more likely than hikes over the next 2–3 years
- You have held variable products before and are comfortable with rate fluctuations
Consider a hybrid split if:
- You want some rate protection but also want to benefit from cuts
- Split example: $400K fixed + $250K variable on the same property
- Reduces worst-case downside while preserving ~60% of the variable upside
There is no universally correct answer. The fixed rate is not “safe” and the variable is not “risky” in absolute terms. The fixed rate is insurance: you pay a premium (higher rate) for certainty. The variable rate is a bet that rates will trend down or stay flat. Over the last 25 years, Canadian variable-rate borrowers have paid less than fixed-rate borrowers in the majority of 5-year periods. Past performance does not guarantee future results, but the historical pattern is worth noting.
What to Ask Your Mortgage Broker
Before committing to either rate type, get clear answers to these questions:
- What is the exact IRD penalty formula? Big banks use posted rates (higher penalty). Monolines and credit unions often use discounted rates (lower penalty).
- Is the variable rate adjustable-payment or fixed-payment? Adjustable changes your payment with each rate move. Fixed keeps the payment constant and adjusts the principal/interest ratio — watch for trigger rate risk.
- What is the trigger rate? On a fixed-payment variable mortgage, this is the rate at which your payment no longer covers the interest. Your balance starts growing. Ask the lender to calculate your specific trigger rate.
- Can I convert variable to fixed mid-term? Most lenders allow this, but you get the current fixed rate at the time of conversion, not the rate available when you signed. This is rarely a good deal.
- What are the prepayment privileges? Most mortgages allow 10–20% annual lump-sum payments. If you redirect variable savings into prepayments, you accelerate principal repayment and reduce total interest further.
Important Disclaimer
This article provides general information about fixed and variable mortgage rates in Canada. It is not financial, mortgage, or legal advice. The fixed rate of 4.99% and variable discount of prime minus 0.75% are representative rates for illustration and may not reflect rates available to you. The Bank of Canada rate projections are based on market consensus as of early 2025 and are not predictions or guarantees. IRD penalty calculations vary significantly by lender. Monthly payment and interest calculations use standard Canadian mortgage math (semi-annual compounding, monthly payments). Ontario land transfer tax figures are based on current provincial legislation. Consult a licensed mortgage broker or financial advisor for advice specific to your situation. For Ontario-specific income tax impacts of homeownership, see our Ontario income tax calculator.