About the Split Loan Calculator
A split loan calculator Australia helps borrowers compare the costs and benefits of dividing their home loan into fixed and variable rate portions. Split loans are a popular strategy among Australian homeowners who want the stability of fixed rates with the flexibility of variable features. This tool helps you find the optimal split ratio for your financial situation.
What is the Split Loan Calculator?
This calculator models how splitting a home loan into two portions affects your total repayments, interest costs, and loan term. A split loan divides the total loan amount into a fixed-rate portion and a variable-rate portion, typically expressed as percentages such as 60/40 or 70/30. The fixed portion locks in an interest rate for a set period, usually 1 to 5 years, protecting against rate rises. The variable portion offers features such as unlimited extra repayments, redraw facility, and an offset account. The calculator compares the total interest payable, monthly repayments, and overall cost under different split scenarios. It also compares a fully variable loan and a fully fixed loan against your chosen split option. Australian borrowers use this tool to decide on the best loan structure when refinancing or taking out a new mortgage. By adjusting the split percentage and interest rates, you can see how different market conditions affect your total cost and find the balance that suits your risk tolerance and financial goals.
How to Use This Calculator
- 1Enter the total loan amount: Input the total mortgage amount you plan to borrow.
- 2Enter the split percentage for fixed portion: Input the percentage of the loan you want on a fixed rate.
- 3Enter the fixed interest rate: Input the fixed rate offered by your lender for the chosen fixed period.
- 4Enter the variable interest rate: Input the current variable rate for the remaining loan portion.
- 5Enter the loan term: Input the total loan term in years, typically 25 or 30 years.
- 6Select the fixed period: Choose how many years the fixed portion will remain fixed before reverting to variable.
- 7Review your comparison: The calculator shows split loan repayments, total interest versus fully variable and fully fixed alternatives.
Worked Australian Example
Practical Example
Emma and Tom are refinancing their home in Adelaide, SA with a total loan of $450,000. They want to split their loan with 60% fixed and 40% variable. The fixed rate is 5.9% for 3 years and the variable rate is 6.4%. The loan term is 30 years. Using the calculator, they enter $450,000 as the total loan, 60% fixed ($270,000), 40% variable ($180,000), 5.9% fixed, 6.4% variable, 30 years, and a 3-year fixed period. The calculator shows the split loan monthly repayment is $2,687. A fully variable loan at 6.4% would cost $2,814 per month, and a fully fixed loan at 5.9% would cost $2,661 per month. Over 3 years, the split loan saves approximately $4,572 compared to fully variable, while maintaining redraw and extra repayment flexibility on the variable portion. Emma and Tom choose the 60/40 split, valuing both the rate security and the flexibility of an offset account linked to the variable portion.
How Our Split Loan Calculator Works
A split loan divides your mortgage into two portions — one **fixed rate** and one **variable rate** — so the calculator computes each portion separately and combines them: 1. **Split the balance** — you choose the proportion (e.g. 50/50 or 70/30). Each split is a loan of its own size. 2. **Amortise each portion** — the fixed split uses the standard repayment formula at the fixed rate; the variable split uses the variable rate. Each has its own principal-and-interest repayment. 3. **Combine** — total repayment is the sum of the two, and total interest is the sum across both splits. The point of splitting is **risk balance**: the fixed portion locks in certainty and protects part of your loan if rates rise, while the variable portion keeps flexibility (extra repayments, offset, redraw) and benefits if rates fall. The trade-off is that you get neither the full protection of an all-fixed loan nor the full flexibility of an all-variable one. Because the variable side moves with the market, the calculator's variable figures assume today's rate and will change if the lender adjusts it.
When to Use This Calculator
Use a split-loan calculator when you're deciding how to structure a new loan or refinance and you're unsure which way rates will move. **At loan setup**, to test different fixed/variable ratios and see the blended repayment for each — helping you pick a mix you're comfortable with. **When rate expectations are uncertain**, since a split hedges your bets rather than committing fully to one direction. **If you want to make extra repayments** but also want some certainty, model how much variable portion you need to keep your offset/redraw useful. It's particularly suited to borrowers who value predictability for budgeting but don't want to lose all flexibility. Re-run it if the lender changes the variable rate to see the new combined repayment.
Common Split Loan Calculator Questions
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