Fixed or variable: how to choose the way your rate is set
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The choice is not a forecast about rates. It is a question about how much a known payment is worth to your household, and how far the variable rate would have to move before the cheaper option stops being cheaper.
Fixed or variable is a question about certainty, not a forecast. A fixed rate is insurance, and the gap between it and the variable rate is the premium — paid every month regardless of what rates do. The question is not whether rates will rise — nobody selling you either product knows that — but whether the certainty is worth the premium to your household, and how far rates would have to move before the fix pays for itself.
What the certainty costs
Take a repayment mortgage of $300,000 over 25 years, with a two-year fix at 5.20% against a variable rate currently at 4.60%.
| Product | Monthly payment | Over two years |
|---|---|---|
| Fixed at 5.20% | $1,788.90 | $42,933 |
| Variable at 4.60%, unchanged | $1,684.57 | $40,430 |
| Difference | $104.33 | $2,504 |
So the fix costs about $2,500 over two years if the variable rate never moves. That is the premium. Now the other side: what the variable rate does to the payment if it does move.
- Variable resets to 5.00% — $1,753.77, still $35 below the fix
- Variable resets to 5.50% — $1,842.26, now $53 above
- Variable resets to 6.00% — $1,932.90, $144 above
- Variable resets to 6.50% — $2,025.62, $237 above
The break-even is not the rate at which the variable passes the fix; it is the point at which the savings banked early cancel out the extra paid later. If the variable sat at 4.60% for a year and then jumped to 6%, the year of savings ($1,252) would be eaten by the second year of higher payments ($1,728), and the fix would have won — narrowly. Run your own version in the repayment calculator; two minutes of arithmetic beats an afternoon of opinions.
What each product actually is
Fixed. The rate is locked for a term — typically two, three, five or ten years. The payment does not move. At the end you revert to the lender's standard rate, which is almost always worse than anything on the open market, so the end of a fix is a date to act on rather than a date to notice.
Tracker. The rate follows a published benchmark plus a fixed margin. It moves in both directions, promptly, and the margin is the part you are actually shopping for. The mechanism is transparent, which is its main virtue.
Standard variable. The lender sets it at their discretion, and the gap between that and what the market is charging is visible in any published rate series — the Bank of England Bank Rate and the weekly Freddie Mac mortgage survey are the usual reference points. They tend to follow increases quickly and decreases slowly. It is rarely the cheapest option and is mostly where borrowers end up by default when a fix expires and nobody acted.
Capped. Variable with a ceiling. The cap is the number to test your budget against, because it is the worst case you have agreed to — not the rate you are paying today.
The fee changes the answer more often than the rate does
Lenders compete on the headline rate because it is what comparison tables sort by, and they recover the difference in the arrangement fee. On a two-year fix, a fee of $1,500 spread over twenty-four payments is $62.50 a month — comparable to a quarter-point difference in rate, and frequently larger.
That is why the comparison has to be made on APR, which folds the fee back into the rate. The APR calculator does that arithmetic. The rule of thumb: the shorter the deal, the more the fee matters, because there are fewer months to spread it over. On a two-year product a large fee is usually decisive; on a ten-year fix it is close to noise.
Where a lender offers to lower the rate in exchange for an upfront payment, the points calculator answers the only question that matters: how many months you have to stay to get your money back.
The cost of changing your mind
A fixed rate is a commitment in both directions. Leaving it early usually triggers an early repayment charge, often a percentage of the balance that steps down each year. On $300,000, a 2% charge is $6,000 — enough to wipe out the advantage of almost any better deal you might move to.
This matters most if there is any chance you will move house, come into money, or want to overpay heavily during the term. Check three things before signing: the early repayment charge and how it tapers, whether the product is portable to a new property, and what the annual overpayment allowance is. Where a switch is on the table anyway, the refinance break-even calculator tells you how long the new deal takes to repay the cost of getting into it.
How to decide without predicting anything
Four questions, in order.
- Could you pay the worst case? For a variable, that is the cap or two to three points above today's rate. If the answer is no, the choice is already made: you cannot afford the risk, whatever it might cost.
- What is the premium worth to you? $104 a month is trivial to one household and impossible for another. Certainty is worth more the tighter the budget.
- How long are you staying? A fix whose term outlasts your plans buys certainty you will pay an exit charge to escape.
- What does the comparison look like on APR? Not on the rate. Fee-inclusive, over the term you will actually hold the product.
Notice that none of the four asks where rates are going. That is deliberate. The forecast is the part nobody can supply, and a decision that only works if the forecast is right is not a decision — it is a bet with your housing costs as the stake.
This is general information, not financial advice. Product names, early repayment rules and stress-test requirements differ by country and by lender, and the worked examples ignore tax and insurance. For a decision about your own mortgage, speak to a regulated adviser or a broker.