How this calculator works

Lenders generally want your loan to be no more than 80% of the property's value without extra protection. If your deposit leaves you above that, a family guarantee can cover the gap: a parent or close relative offers equity in their own property as additional security for that portion of your loan. That can let you buy sooner, and often avoid Lenders Mortgage Insurance on that portion.

The calculator takes the part of your loan above 80% of the purchase price as the likely guarantee amount, then checks it against the usable equity in your guarantor's property – 80% of its value, less what they still owe. It also shows roughly how much you'd need to pay down before the guarantee could come off, assuming the property value stays the same.

What your guarantor should know

  • A guarantee is a real commitment – if repayments were ever missed, the lender could look to the guarantor for the guaranteed amount
  • Ask whether the guarantee is limited to a set amount, and how and when it can be released
  • It can affect your guarantor's own borrowing capacity while it's in place
  • Guarantors should take independent legal advice before signing – many lenders require it

For the full picture, read how guarantor home loans work or our guide to family guarantees.

General information only. This calculator is general in nature and doesn't take into account your personal financial situation, objectives or needs. It isn't tax, legal or financial advice. Lending criteria and policies on guarantees vary between lenders and change over time – always confirm current detail with your broker before making decisions.

Frequently asked

How much guarantee would I need?

Typically the part of your loan that sits above 80% of the purchase price. For example, on an $800,000 purchase with a $40,000 deposit you'd borrow $760,000; 80% of the price is $640,000, so the guarantee would be about $120,000. Lenders set their own rules, so treat this as a guide.

Does a guarantor have to own their home outright?

No. What matters is usable equity. Lenders look at the value of the guarantor's property, any loan against it and their own financial position. Many lenders work to around an 80% combined loan-to-value ratio on the guarantor's property, though policies differ.

Can a guarantee be released?

Often yes, once your loan has been reduced to a level the lender is comfortable with – frequently around 80% of the property's current value – through repayments, value growth or both. The lender decides, and may require a valuation and a formal release process.

Is this calculator a quote or an approval?

No. It gives an indicative estimate using common rules of thumb. It doesn't account for your income, expenses, fees or a specific lender's policy, and it isn't credit advice. A broker can check what actually applies to your situation.