Split Loan Calculator
Calculate your repayments and total interest when splitting your home loan between fixed and variable rates.
| Weighted Average Rate | 0% |
| Total Interest | $0 |
| Fixed Portion Amount | $0 |
| Fixed Monthly Repayment | $0 |
| Variable Portion Amount | $0 |
| Variable Monthly Repayment | $0 |
How Split Home Loans Work in Australia
A split loan divides your mortgage into two separate sub-accounts: one on a fixed interest rate and one on a variable rate. You choose what percentage goes to each portion. Both portions form part of the one mortgage against your property, but they operate with separate interest rates, repayments, and features.
Why Split Your Loan?
A split loan is the "have your cake and eat it too" approach to the fixed vs variable dilemma. The fixed portion gives you certainty — you know exactly what that repayment will be regardless of RBA rate movements. The variable portion gives you flexibility: you can make unlimited extra repayments, attach an offset account, and benefit if rates fall. Many Australian borrowers find this balance appealing, particularly when rates are uncertain.
Understanding the Weighted Average Rate
The weighted average rate shown in the results is the single effective rate across your entire loan. It's calculated as: (fixed portion × fixed rate + variable portion × variable rate) ÷ total loan. This makes it easy to compare your split loan against a single-rate product. If the weighted average rate is lower than any single-rate alternative, the split may be the better deal overall.
A worked example
$700,000 split 50/50, fixed at 5.9% and variable at 6.5% over 30 years. The blended rate is 6.20%, the combined repayment $4,288 a month, and total interest $843,758 across the term. These rates are illustrative inputs, not a market quote. They are the same rates the table below uses, and they match what this calculator returns.
Three splits of the same loan
Same loan, same term, same two rates. Only the mix changes. Monthly figures are rounded to the nearest dollar, which is how the 50/50 row above is shown.
| Fixed share | Variable share | Blended rate | Monthly repayment | Total interest |
|---|---|---|---|---|
| 100% · $700,000 | None | 5.90% | $4,152 | $794,704 |
| 80% · $560,000 | 20% · $140,000 | 6.02% | $4,206 | $814,325 |
| 50% · $350,000 | 50% · $350,000 | 6.20% | $4,288 | $843,758 |
| 20% · $140,000 | 80% · $560,000 | 6.38% | $4,370 | $873,190 |
| None | 100% · $700,000 | 6.50% | $4,424 | $892,811 |
Moving from all-fixed to all-variable on these rates costs about $272 a month and about $98,000 of extra interest over 30 years. People still keep a variable slice for the features, not the rate. Extra repayments are usually unlimited on the variable portion and capped on the fixed portion, and an offset account normally attaches only to the variable balance. A bonus can go in as a lump sum or as a regular extra. Breaking the fixed slice early is a break cost. If you are considering interest-only on the variable half, the interest-only switch calculator shows what that does to the balance you still owe. The fully fixed and fully variable ends of this table are what the fixed versus variable calculator compares on their own.
Choosing Your Split Ratio
The right split depends on your priorities:
- Larger fixed portion (e.g. 70–80%): More rate certainty, stable budgeting, less interest rate risk. Better if you're on a tight budget or expect rates to rise.
- Larger variable portion (e.g. 70–80%): More flexibility for extra repayments and offset savings. Better if you have surplus income to put to work reducing the loan.
- 50/50: A balanced approach that many borrowers start with. Easy to understand and provides meaningful exposure to both benefits.
Offset Accounts and Split Loans
One important consideration: offset accounts typically only apply to the variable portion. Your offset savings reduce interest only on the variable sub-account. If maximising offset benefits is your goal, a larger variable portion makes sense. Use our Offset Savings Calculator to model how much your offset savings could reduce interest on the variable portion.