Loan Top-Up Calculator
Work out the new repayment and total interest impact of topping up your existing mortgage to borrow additional funds.
Your results
Calculation breakdown
- New repayment
- Annuity formula on (current balance + top-up) over the remaining term
Worked example
Topping up a $400,000 loan by $50,000 at 6% over 25 years adds about $322 a month and roughly $46,600 in extra interest.
Assumptions
- Assumes the top-up is repaid over the same remaining term as the existing loan.
- Does not include lender valuation or top-up establishment fees.
How this calculator works
This calculator adds a top-up amount to your current mortgage balance and recalculates the repayment over the remaining term, showing how much extra you would repay each period and in total interest for accessing the additional funds.
Frequently asked questions
What is a loan top-up used for?
Borrowers commonly top up a mortgage to fund renovations, debt consolidation or a large purchase, using existing home equity rather than taking out a separate loan.
Will the lender require a new valuation?
Most lenders require a valuation and reassessment of your borrowing capacity before approving a top-up, since it increases your total debt against the property.
Does topping up reset my loan term?
This calculator assumes the top-up is repaid over your existing remaining term; some lenders may offer a fresh full term instead, which would lower repayments but increase total interest.
Results are estimates only and are not financial, tax, legal or credit advice.