Mortgage & offset calculator
Calculate repayments and the effect of an offset or extra payments.
Example plan · try your own numbers
Your projected balance
Enter your numbers to see the possibilities.
Loan balance & payoff
Save, export & assumptions
Estimates only. Assumes unchanged rates, no withdrawals, tax or fees. Monthly approximation; your bank’s daily calculation and product rules may differ. Calculation details →
See the numbers behind the picture
How it works & common questions
Look beyond the monthly repayment.
Your regular repayment covers interest and reduces the loan principal. An offset can reduce the balance used to calculate interest; an extra repayment directly reduces what you owe. Both can change the total cost and repayment time.
How this calculator works
The base payment uses the standard amortising-loan formula. Each month we calculate interest on the loan balance less the constant offset (never below zero), then subtract your payment and any extra repayment. We compare that schedule with the same loan without either feature.
View formulas and limitations →
Further reading: ASIC’s Moneysmart ↗
A few good questions.
Does an offset reduce the repayment shown?
The regular repayment is calculated from the original loan, interest rate and term. We hold it fixed so less interest means more principal is repaid. Your lender may apply different repayment rules.
Are fees or interest-only periods included?
No. This models a principal-and-interest loan with a constant rate, monthly payments and a full offset. It excludes lender fees, insurance, rate changes, interest-only periods and tax.
Is the offset money used to pay off the loan?
No. It remains in the separate offset account throughout the model. Repayments continue until the loan balance reaches zero; the offset is not counted as a final lump-sum repayment.