Home Equity Calculator Australia

What home equity is and how it is calculated

Home equity is the difference between the current market value of a property and the total debt secured against it. A property valued at $900,000 with a loan balance of $500,000 carries equity of $400,000. Equity is a measure of ownership, not a cash balance. It cannot be spent directly, and it becomes available only when the property is sold or when a lender agrees to advance further funds against it. Where more than one loan is secured against the same property, including a line of credit or a loan supported by a guarantee, all of the secured balances are counted as debt for this purpose.

Equity grows in two ways. Each principal repayment reduces the debt, and funds held in an offset account or made as extra repayments accelerate that process. Equity also rises when the market value of the property increases, whether through general price growth or through improvements such as a renovation. The reverse also applies. If property values fall, equity contracts even though the loan balance is unchanged, and an owner with an interest-only loan builds equity through price growth alone during the interest-only period.

How the home equity calculator works

The calculator requires two inputs: the current value of the property and the loan balance owing. It produces three principal results. Total equity is the value less the loan balance. Usable equity is 80% of the value less the loan balance, and it is shown as nil where the loan already exceeds 80% of the value. The current LVR is the loan balance divided by the value, expressed as a percentage, and a bar beneath the result shows the split between debt and equity.

The tool also converts usable equity into an approximate purchase price for an investment property. That guide assumes that the usable equity must cover a 20% deposit together with purchase costs of about 5% of the price, so the indicative purchase is approximately four times the usable equity, rounded down to the nearest $10,000. The calculator does not assess income, expenses or existing commitments. It therefore indicates what the security might support, and not what a lender would approve.

Usable equity and the 80% LVR rule

Usable equity is the portion of total equity that a lender may be prepared to lend against without lenders mortgage insurance. Lenders generally limit standard lending to 80% of the value of the security, so that a buffer remains if the property must be sold. The prudential standards of the Australian Prudential Regulation Authority require authorised deposit-taking institutions to set appropriate LVR limits and to value security conservatively, and the 80% convention reflects that framework.

An illustrative example shows the calculation. For a hypothetical property valued at $900,000 with a loan balance of $500,000, total equity is $400,000 and the current LVR is 55.6%. Eighty per cent of the value is $720,000, and after the $500,000 loan is deducted, usable equity is $220,000. The remaining $180,000 of equity is the buffer that stays in the property. If the owner borrowed the full $220,000, total debt would be $720,000 and the LVR would be exactly 80%.

How much equity can be accessed in practice

The amount of equity that can be accessed depends on three matters: the valuation adopted by the lender, the maximum LVR the lender will accept, and the capacity of the borrower to service the larger debt. The valuation is frequently the first constraint. Lenders rely on their own valuation, which may be a full inspection, a kerbside assessment or an automated model, and which may be more conservative than an appraisal by a real estate agent or an online estimate. A lower valuation reduces usable equity dollar for dollar at the 80% level.

Serviceability is the second constraint. A lender assesses whether the borrower is able to afford repayments on the total debt after the increase, using an interest rate that includes a buffer above the actual rate and taking account of living expenses and other commitments. An owner may hold substantial usable equity and still be declined because income does not support the additional borrowing. The BorrowWise borrowing power calculator provides an indication of the total debt that a given income may support.

Some lenders permit borrowing above 80% of the value, commonly to 90%, subject to lenders mortgage insurance. In the hypothetical example above, a limit of 90% would allow total debt of $810,000 and accessible equity of $310,000, but an insurance premium would be payable on the enlarged loan and the buffer against a fall in value would be thinner. The BorrowWise LMI calculator provides an indicative estimate of that premium.

How changes in property value affect usable equity

Usable equity is sensitive to movements in value, because the 80% limit is applied to the whole property value while the loan balance is fixed. In the hypothetical example, a 10% fall in value from $900,000 to $810,000 reduces total equity from $400,000 to $310,000. Eighty per cent of $810,000 is $648,000, so usable equity falls from $220,000 to $148,000 and the current LVR rises from 55.6% to 61.7%. A fall of 10% in value has reduced usable equity by about one third.

The same arithmetic works in the other direction. An increase in value to $1,000,000 lifts the 80% limit to $800,000 and usable equity to $300,000, which is $80,000 more than before. This sensitivity is one reason why lenders insist on a current valuation before releasing equity, and why an estimate made in a rising market may not hold at a later date. Owners who have already borrowed to an LVR of 80% have no usable equity to draw upon if values decline, and may find that refinancing to another lender becomes more difficult or more costly until the LVR has been reduced again.

Ways to access equity in a home

The most common method is a loan increase, sometimes called a top-up, with the existing lender. The borrower applies to raise the loan limit, the lender obtains a valuation and reassesses serviceability, and the additional funds are usually established as a separate loan split. A separate split keeps the new borrowing distinct from the original home loan, which assists record keeping where the funds are applied to an investment purpose. Interest on borrowed funds is generally deductible only to the extent that the funds are used to produce assessable income, regardless of which property secures the loan.

A second method is to refinance the whole debt with another lender at a higher limit, which may also provide an opportunity to obtain a lower interest rate. Discharge fees, application fees and government registration charges apply, and the BorrowWise refinance calculator may be used to weigh those costs against the saving. A third method is a line of credit secured against the property, which allows funds to be drawn as required up to an approved limit. Lines of credit often carry higher interest rates and demand discipline, because there may be no obligation to repay principal.

Using equity as a deposit for an investment property or a renovation

Equity is frequently used in place of a cash deposit for an investment property. The owner borrows against the existing home to fund the deposit and the purchase costs, and takes a second loan secured by the new property for the balance. In the hypothetical example, usable equity of $220,000 indicates a purchase of approximately $880,000: a 20% deposit of $176,000 and costs of about $44,000, which together total $220,000. The purchaser would then owe the full purchase price and costs across the two loans.

Transfer duty is usually the largest of those purchase costs and varies considerably between jurisdictions, so the BorrowWise stamp duty calculator may be used to refine the estimate for the state or territory in which the investment is located. An investment purchase does not attract first home buyer relief, and in some jurisdictions investors pay a higher rate of duty than owner-occupiers. The investment property calculator and the rental yield calculator may then assist in assessing whether the expected rent is likely to support the additional debt, since the lender will assess repayments on both loans together.

Renovations are the other common purpose. As a hypothetical illustration, drawing $100,000 for a renovation would raise the loan from $500,000 to $600,000 and the LVR from 55.6% to 66.7%, leaving usable equity of $120,000 on the original valuation. Lenders may request quotations or a building contract, and structural work is sometimes funded through a construction loan with staged payments. A renovation does not necessarily add value equal to its cost, so the equity drawn may not be fully restored when the work is complete.

Risks of borrowing against home equity

Borrowing against equity increases total debt and places the home at risk if repayments cannot be maintained. Where the funds are invested, a fall in the value of the investment does not reduce the amount owing, so losses are magnified as well as gains. Where one lender holds several properties as security for several loans, an arrangement known as cross-collateralisation, the sale or refinancing of one property may require the consent of the lender and a revaluation of the others. Many borrowers prefer separate, stand-alone securities for that reason.

Higher debt also increases exposure to interest rate rises. The Reserve Bank of Australia observed in its March 2026 Financial Stability Review that most households with mortgages were in a solid financial position, while noting that some continued to experience budget pressures. A borrower who draws equity close to the 80% limit reduces the buffer that protects against both outcomes. This guide provides general information only, and an accredited mortgage broker or a licensed financial adviser is able to consider individual circumstances.