This guide covers general concepts that apply in the US, UK, Canada and Australia. It is educational content, not financial advice.
Once you have found a home and a lender, one of the biggest decisions left is how your interest rate will behave. Will it stay the same for years, or move up and down with the market? That single choice can change your monthly payment by hundreds and your total cost by thousands.
In this guide we compare fixed-rate and variable-rate mortgages side by side, run the numbers on real examples, and walk through the questions that help you decide which one suits your situation. If you are new to home loans, you may want to start with our guide on how a mortgage works first.
What Is a Fixed-Rate Mortgage?
With a fixed-rate mortgage, your interest rate is locked for an agreed period. As long as that period lasts, your principal and interest payment stays exactly the same every month, no matter what happens to the wider economy.
How long the rate stays fixed depends a lot on where you live:
- United States. Most borrowers fix for the entire life of the loan, usually 15 or 30 years. The rate you get on day one is the rate you pay until the loan is paid off or refinanced.
- United Kingdom. Fixed deals typically last two, three, five or sometimes ten years. When the deal ends, the loan moves to the lender’s standard variable rate (SVR) unless you remortgage onto a new deal.
- Canada. Rates are fixed for the length of your mortgage term, most often five years, even though the loan is amortized over 25 years or more. At the end of the term you renew at whatever rates are available then.
- Australia. Fixed periods are usually between one and five years, after which the loan normally reverts to a variable rate.
So outside the US, “fixed” almost always means fixed for a few years, not forever. That is an important detail when you compare advice from different countries.
What Is a Variable-Rate Mortgage?
With a variable-rate mortgage, your interest rate can change during the loan. It usually moves in line with a benchmark, such as a central bank rate or the lender’s own standard rate. When the benchmark goes down, your payment can fall. When it goes up, your payment can rise.
Variable loans come in several forms:
- Adjustable-rate mortgages (ARMs) in the US. Most start with a fixed introductory period, for example five, seven or ten years, and then adjust at set intervals. A “5/1 ARM” is fixed for five years and then adjusts once a year. ARMs usually include caps that limit how much the rate can rise at each adjustment and over the life of the loan.
- Tracker mortgages in the UK. These follow the Bank of England base rate plus a fixed margin. If the base rate rises by 0.25%, your rate rises by the same amount.
- Standard variable rate (SVR) loans. The lender sets this rate and can change it at its discretion. It is often higher than other deals, which is why many UK borrowers try to avoid staying on it for long.
- Variable-rate mortgages in Canada. Rates move with the lender’s prime rate. Some variable loans keep your payment the same and change how much goes toward principal, while adjustable ones change the payment itself.
- Variable home loans in Australia. These are very common and often come with extra features such as offset accounts and redraw facilities.
Fixed vs Variable at a Glance
| Feature | Fixed rate | Variable rate |
|---|---|---|
| Monthly payment | Stays the same during the fixed period | Can go up or down |
| Starting rate | Often slightly higher | Often slightly lower |
| Budgeting | Easy and predictable | Needs a buffer for increases |
| If rates fall | You keep paying the higher rate | Your payment can drop |
| If rates rise | You are protected | Your payment can rise |
| Early repayment | Often higher fees or limits | Usually more flexible |
| Extra features | Fewer | Often more (offset, redraw, overpayments) |
How Much Difference Does the Rate Make?
Rate differences that look tiny on paper become large once they are spread over a big loan. Here is the monthly principal and interest payment on a $300,000 loan over 30 years at different rates:
| Interest rate | Monthly payment |
|---|---|
| 5.0% | $1,610 |
| 5.5% | $1,703 |
| 6.0% | $1,799 |
| 6.5% | $1,896 |
| 7.0% | $1,996 |
| 7.5% | $2,098 |
Every half percentage point moves the payment by roughly $95 to $100 a month on this loan. That is why the direction of rates matters so much to anyone on a variable mortgage.
A Worked Example: Five Years on Fixed vs Variable
Let’s compare two borrowers who each take out a $300,000 loan over 30 years. We will look at the first five years, since that is a common fixed period in many countries.
- Borrower A chooses a fixed rate of 6.0% for five years.
- Borrower B chooses a variable rate that starts at 5.5%.
Borrower A pays $1,799 a month for the whole five years. Total paid: about $107,900.
What Borrower B pays depends on what happens to rates. Here are three possible paths, where the rate stays at 5.5% for two years and then changes for the remaining three:
| Scenario for Borrower B | Payment years 1 to 2 | Payment years 3 to 5 | Total paid over 5 years | Compared with fixed |
|---|---|---|---|---|
| Rates fall to 5.0% | $1,703 | $1,615 | about $99,000 | about $8,900 less |
| Rates stay at 5.5% | $1,703 | $1,703 | about $102,200 | about $5,700 less |
| Rates rise to 7.0% | $1,703 | $1,982 | about $112,200 | about $4,300 more |
Figures are illustrations only, rounded, and exclude fees, taxes and insurance.
A few things stand out:
- The variable loan wins in two of the three scenarios. Because it started lower, Borrower B built up savings in the early years.
- The downside is real. If rates jump, Borrower B’s payment rises by almost $280 a month. The total cost ends up higher, and the jump in monthly cost can strain a tight budget.
- Certainty has a price. Borrower A pays a little more in the good scenarios in exchange for knowing exactly what each month will cost.
In other words, a fixed rate works like insurance against rising rates. Whether that insurance is worth paying for depends on your budget and how much risk you can comfortably take on.
Pros and Cons of a Fixed-Rate Mortgage
Advantages
- Predictable payments. You know exactly what you will pay, which makes budgeting simple.
- Protection from rate rises. If central banks raise rates, your payment does not change during the fixed period.
- Peace of mind. Many first time buyers value knowing their largest monthly bill will not suddenly jump.
Disadvantages
- Usually a higher starting rate. Lenders often charge a premium for taking on the rate risk.
- You miss out if rates fall. Your payment stays the same even if market rates drop sharply.
- Early repayment charges. Leaving a fixed deal early, to sell or refinance, can trigger significant fees in many countries. In Canada, for example, breaking a fixed-rate mortgage early can be expensive.
- Less flexibility. Some fixed deals limit how much you can overpay each year.
Pros and Cons of a Variable-Rate Mortgage
Advantages
- Often a lower starting rate. This can mean lower payments at the beginning of the loan.
- You benefit when rates fall. Your payment can drop without you needing to refinance.
- More flexibility. Variable loans often allow unlimited overpayments and lower exit fees, and in Australia they are more likely to offer offset accounts.
Disadvantages
- Payment uncertainty. Your monthly cost can rise, sometimes quickly, if rates go up.
- Harder to budget. You need a financial buffer to absorb possible increases.
- Stress in a rising market. Borrowers who took variable loans just before a cycle of rate rises can face a significant jump in payments.
Which Is Better for You? Questions to Ask Yourself
There is no answer that fits everyone. Instead, work through these questions honestly.
How tight is your budget?
If a rise of a few hundred a month would cause real stress, a fixed rate is usually the safer choice. If you have spare income and savings, you are in a better position to handle a variable rate.
How long will you keep the loan?
If you plan to sell or refinance within a few years, check early repayment charges carefully. A variable loan or a short fixed term may give you more freedom to move without large fees.
What is your appetite for risk?
Some people are comfortable with ups and downs if they may save money over time. Others would rather pay a little more to sleep well at night. Neither attitude is wrong, but your choice should match yours.
How big is the gap between the rates?
When fixed and variable rates are close together, locking in certainty costs very little. When the fixed rate is much higher, the variable option has a bigger head start, as the worked example showed.
Do you need flexibility?
If you expect a bonus, inheritance or other lump sum and want to pay down the loan faster, the overpayment rules of each product may matter more than the headline rate.
What About Where Rates Are Heading?
Many people try to choose based on rate forecasts. It is sensible to be aware of the general direction central banks are signaling, but nobody can reliably predict rates several years ahead. Economists and lenders have often been wrong about the timing and size of rate changes.
A more reliable approach is to ask: “Could I still afford my payments if rates rose by 2 or 3 percentage points?” This is similar to the stress tests used by lenders in Canada, the UK and Australia. If the answer is no, a fixed rate gives you important protection. If the answer is yes, you have more freedom to choose based on cost and flexibility.
Other Options Worth Knowing
You are not always limited to a simple choice between the two:
- Split loans. Common in Australia and available from some lenders elsewhere, these let you fix part of your loan and keep the rest variable. You get some certainty and some flexibility.
- Hybrid ARMs. In the US, a 5/1, 7/1 or 10/1 ARM gives you a fixed rate for several years and then adjusts. These can suit buyers who expect to move or refinance before the fixed period ends.
- Capped rates. Some lenders offer variable rates with a ceiling, so your rate cannot rise above a set level during the deal.
- Offset mortgages. In the UK and Australia, an offset account links your savings to your mortgage, so you pay interest only on the difference.
Common Mistakes to Avoid
- Choosing only on the starting rate. A lower variable rate is not a bargain if a rise would stretch your budget too far.
- Ignoring fees and exit charges. Compare the APR or comparison rate, not just the headline rate.
- Forgetting the end of a fixed deal. In the UK, Canada and Australia, set a reminder several months before your fixed period ends so you can compare new deals instead of rolling onto a higher rate.
- Trying to time the market perfectly. Base your decision on what you can afford, not on a guess about next year’s rates.
Frequently Asked Questions
Is a fixed or variable mortgage cheaper?
Variable rates often start lower, so they can be cheaper when rates stay flat or fall. Fixed rates tend to cost more upfront but protect you if rates rise. Which one turns out cheaper depends on how rates move during your loan.
Can I switch from a variable to a fixed rate later?
Often yes. Many lenders let you move from variable to fixed, sometimes without a fee. Switching from fixed to variable during a fixed period is usually harder and may trigger early repayment charges.
What happens when my fixed rate ends?
In the UK and Australia, your loan usually moves onto the lender’s variable rate. In Canada, you renew your mortgage for a new term. In the US, a standard fixed loan simply keeps the same rate until it is paid off, while an ARM starts adjusting.
Are variable-rate mortgages risky?
They carry more payment risk because your costs can rise. That risk is manageable if you have a comfortable budget and savings, but it can be serious for borrowers with little room to spare.
The Bottom Line
Neither a fixed-rate nor a variable-rate mortgage is better for everyone. A fixed rate gives you stability and protection from rising rates, usually at a slightly higher cost. A variable rate often starts cheaper and offers more flexibility, but your payments can rise if the market turns.
The right choice comes down to your budget, your plans and how much uncertainty you can live with. Compare real offers from several lenders, check the fees and exit charges, and test whether you could handle a rate rise before you commit. If you are unsure, a licensed mortgage adviser or broker in your country can help you compare options for your situation.
Disclaimer: This article is for general educational purposes only and does not constitute financial, legal or tax advice. Mortgage products, rates and rules differ by country and lender and change over time. Always confirm details with a qualified professional and your lender before making decisions.