🏠 Fixed vs Variable-Rate Mortgage: Which Saves You More?
Your lender offers you two deals on the same house: 7% fixed, or 5.5% variable. The variable payment is $293 a month cheaper, and that money is tempting. But the cheap rate is only the opening chapter — the reset, years later, is where the real cost is decided.
How a fixed-rate mortgage works
A fixed rate never moves for the life of the loan. On a $300,000 loan over 30 years at 7% fixed, the principal-and-interest payment is $1,995.91 every month, from the first payment to the last. Total interest over the full term: $418,527.
That certainty is the product: you pay a premium — fixed rates usually start higher — for a payment you can budget around for decades. If rates rise, you win; if they fall, refinancing remains an option, at a cost.
How a variable-rate mortgage works
A variable (adjustable) rate starts low, stays fixed for an initial period — commonly 5 years — and then adjusts, usually once a year, following a benchmark index plus the lender's margin. The same $300,000 loan at an initial 5.5% costs $1,703.37 a month, which is $292.54 less than the fixed payment. Over the first five years that is about $17,550 less out of your pocket.
Then comes the reset. Your rate is recalculated, and your payment with it. Three caps decide how bad that reset can get, and you must read them before signing: the initial cap (how much the rate can jump at the first adjustment), the periodic cap (how much it can move at each later adjustment) and the lifetime cap (the highest it can ever go). With a lifetime cap of 10.5%, a 5.5% start can, in the worst case, cost far more than the fixed deal.
The same loan, four outcomes
Here is what happens to that $300,000, 30-year loan under four paths. The variable paths all start at 5.5% for five years; only the rate after the reset differs.
- Fixed at 7% all along: $1,995.91 a month, $418,527 total interest.
- Variable, then 6.5%: payment rises to $1,872.90, total interest $364,073 — about $54,454 less than fixed.
- Variable, then 7.5%: payment rises to $2,049.83, total interest $417,150 — still $1,377 less than fixed, because the cheap first five years banked enough savings to absorb the higher later rate.
- Variable, then 8.5%: payment jumps to $2,233.55, total interest $472,268 — about $53,741 more than fixed.
The answer depends almost entirely on where rates go after the reset — the one thing nobody can promise at signing. Run your own numbers with our Mortgage Calculator before you decide, changing the rate to each reset scenario.
Five questions that settle it for you
1. How long will you actually stay? If you are fairly sure you will move or refinance within the initial fixed period, the variable loan's cheap opening years are nearly pure saving, and you may never meet a reset.
2. Could you afford the payment at the lifetime cap? Test affordability at the worst rate the contract allows, not the starting rate: if that payment breaks your budget, variable is a gamble you cannot afford to lose.
3. How much of your income is already spoken for? A household with margin can absorb a $250 monthly jump; one already stretched by the fixed payment cannot.
4. What do you believe about rates? This is a forecast, not knowledge — and the market has already priced that expectation into the fixed rate you were offered.
5. What does extra money do in each case? Check extra payments with our Mortgage Payoff Calculator: on a variable loan, payments made during the cheap years cut the balance before any reset bites.
Three traps to avoid
The teaser trap. Some variable deals advertise a very low first-year rate that is not the real initial rate at all. Ask for the rate that applies for the whole initial period, not the headline.
The refinance rescue trap. “I will just refinance before the reset” only works if your income, credit and home value still qualify in five years, and if rates then are attractive. Treat refinancing as a bonus, never as the plan.
The spent-saving trap. The $293 a month a variable loan saves at the start feels like extra income. It is not. Borrowers who bank it survive a reset calmly; borrowers who spend it meet the reset with no cushion.
The verdict
Choose fixed if you plan to stay long, your budget has little slack, or a higher payment would keep you awake at night. Certainty has a price, and for most first-time buyers it is worth paying. Choose variable only if you will probably move before the reset, you can comfortably afford the payment at the lifetime cap, and you will bank — not spend — the early saving. And whichever you choose, confirm the size of the loan itself first with our House Affordability Calculator: the cheapest rate on a loan that is too large is still a loan that is too large.
Frequently asked questions
Is a variable-rate mortgage always cheaper at the start?
Almost always, yes — lenders price the initial variable rate below the fixed rate to attract borrowers. On a $300,000 loan, 5.5% variable costs $1,703.37 a month against $1,995.91 at 7% fixed. The saving is real, but it is temporary by design.
What are rate caps, and why do they matter?
Caps limit how far your rate can rise: at the first adjustment, at each later adjustment, and over the life of the loan. The lifetime cap is the number that matters most — it sets your worst-case payment. Always ask for all three caps in writing before signing.
Can I switch from variable to fixed later?
Usually only by refinancing, which means a new application, new fees and qualifying again at that time. A few loans offer a conversion option for a fee; check whether yours does before you rely on it.
If I plan to move in five years, is variable the obvious choice?
It is often the better choice, because you collect the cheap opening years and sell before the reset. But only if the move is likely, not merely hoped for — a job change or market fall that delays the move leaves you facing the reset you planned to escape.