One of the most important decisions you make when taking out a loan is choosing between a fixed or variable interest rate. Get it right and you could save thousands over the life of the loan. Get it wrong and you could end up paying far more than you anticipated. This guide explains exactly how each works and how to choose the right option for your situation.
What is a fixed interest rate?
A fixed interest rate stays the same for the entire life of the loan — or for a set fixed period. Your monthly repayment never changes, regardless of what happens to interest rates in the broader economy. If you lock in at 6.5%, you pay 6.5% from the first payment to the last.
Fixed rates give you certainty. You can budget accurately because your repayment is predictable. This makes them popular for mortgages, personal loans, and car finance where people want stability.
What is a variable interest rate?
A variable interest rate moves up or down in line with a benchmark rate — typically the central bank's base rate or an interbank lending rate. When that benchmark rises, your rate rises. When it falls, your rate falls. Your monthly repayment changes accordingly.
Variable rates are often lower than fixed rates at the point of signing because the lender isn't taking on the risk of rate increases — you are. But if rates fall after you take the loan, you automatically benefit without having to refinance.
Key differences at a glance
Fixed rate
- Repayment never changes
- Easy to budget
- Protected from rate rises
- Miss out if rates fall
- Often slightly higher starting rate
- May have early exit fees
Variable rate
- Repayment can rise or fall
- Harder to budget precisely
- Benefit if rates fall
- Exposed to rate rises
- Often lower starting rate
- Usually more flexible
When fixed rates make more sense
A fixed rate is generally the better choice when:
- Interest rates are currently low — locking in a low rate protects you if rates rise later
- You need budget certainty — you can't absorb an increase in repayments if rates rise
- You're taking a long-term loan — the longer the term, the more exposure you have to rate volatility with a variable rate
- Rates are expected to rise — if economic conditions suggest rates will increase, fixing now saves money later
When variable rates make more sense
A variable rate is generally the better choice when:
- Interest rates are high and expected to fall — a variable rate means you automatically benefit from any cuts
- You plan to pay off the loan early — variable loans typically have fewer early repayment penalties
- You want flexibility — variable loans often allow overpayments and lump sum repayments more freely
- The rate differential is significant — if the variable rate is substantially lower than the fixed rate, the savings may outweigh the risk
The split loan option
Many lenders offer a split loan — where part of your loan is on a fixed rate and part is on a variable rate. This gives you the certainty of fixed payments on a portion of the loan while still benefiting from rate falls on the rest. It's a useful compromise if you're unsure which direction rates will go.
💡 No one can predict interest rate movements with certainty — not economists, not central banks, not financial advisors. The right choice depends on your personal risk tolerance and financial situation, not on trying to predict the future.
What about the break cost on fixed loans?
If you want to exit a fixed rate loan early — because you're selling the property, refinancing, or making a large lump sum payment — you may face a break cost. This is a fee the lender charges to compensate for the loss of interest income.
Break costs can be substantial, sometimes running into thousands of dollars. Always ask your lender about break costs before fixing your rate, and factor them into your decision if you think your circumstances might change during the fixed period.
How to compare your options
When comparing fixed vs variable loan offers, look beyond the advertised interest rate. Compare the comparison rate or APR, which includes fees and charges. A loan with a slightly higher interest rate but lower fees may cost less overall than a loan with a low headline rate but high establishment and annual fees.
Use our loan calculator to model both scenarios side by side — enter the fixed rate for one calculation and the variable rate for another. Compare the total interest payable over the full term to see the real cost difference.
Compare fixed and variable rate scenarios with our free loan calculator.
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