How Much Equity Can I Borrow? A Homeowner’s Calculation Guide

“How much equity can I borrow?” needs two calculations, not one. The first estimates how much room there is between the home’s value and the debt already secured against it. The second asks whether your household can afford another loan. Passing the first test does not guarantee passing the second.

Quick answer

The equity you can borrow is not simply your home’s value minus the mortgage. A common planning estimate is 80% of the lender’s valuation less existing secured debt, but approval also depends on income, expenses, liabilities and lending policy. Obtain a valuation and affordability assessment before committing to spend the money.

How much equity can I borrow: start with two figures

Write down the current property value and the outstanding secured debt. Subtracting the debt gives total equity. If a home is worth $900,000 and the mortgage is $500,000, total equity is $400,000. That is a balance-sheet figure, not $400,000 waiting in a bank account.

ANZ’s explanation of home equity distinguishes property equity from the amount that may be available to borrow. The lender still needs to consider the loan, property and borrower. Use its accepted valuation and ask which existing balances or limits it includes in the assessment.

Do not add redraw and equity together without understanding the loan. Available redraw relates to the account’s terms and additional repayments; borrowing against equity is a credit decision. Our offset versus redraw guide explains why account balances and access rights need separate treatment.

The common 80% planning calculation

A frequently used starting point is property value multiplied by 80%, less the existing secured debt. For the example above, $900,000 multiplied by 80% is $720,000. Subtract the $500,000 mortgage and the planning estimate is $220,000.

This example assumes one property and a straightforward debt position. It is not a loan offer. Fees, other secured facilities, the lender’s treatment of limits and the proposed structure can change the amount available.

Borrowing above 80% may be possible in some situations, but conditions and costs can differ. Our lenders mortgage insurance guide explains one cost that may become relevant. Do not assume that paying insurance guarantees approval or protects you from repayment difficulties.

A lower valuation changes the result quickly

Suppose the lender values the same home at $850,000 rather than $900,000. At the same 80% planning ratio, the ceiling becomes $680,000. After the $500,000 debt, the estimated room is $180,000: $40,000 less than the first calculation.

This is why a renovation contract or investment purchase should not be based solely on an optimistic online estimate. Ask when the valuation happens, whether there is a fee and what occurs if it comes in below expectations.

An improvement’s cost is not automatically added dollar for dollar to the valuation. A $50,000 renovation does not establish a $50,000 increase in lender-assessed value. The local market, property and valuation process matter.

Affordability can be the tighter limit

A household can have substantial equity and limited capacity to service more debt. Income, living expenses, dependants, other loans and credit facilities all affect the assessment. The lender may approve less than the equity worksheet suggests or decline the additional borrowing.

Use our borrowing-capacity guide to prepare the household information. Do not confuse a quick calculator result with a formal assessment. Explain upcoming changes such as reduced hours, parental leave or retirement when discussing the application.

Ask for the proposed repayment at the offered rate and a higher-rate scenario. A budget that works only at today’s repayment, with no room for repairs or income disruption, is a warning even if the lender is willing to proceed.

Decide what amount is actually needed

Start with the purpose and an itemised budget. For renovations, separate the builder’s quote, approvals, temporary accommodation if needed and a realistic contingency. For another purchase, include transaction costs rather than treating the deposit as the complete funding requirement.

The maximum available amount is not automatically the appropriate amount to draw. Borrowing an extra $20,000 “just in case” can create interest costs if it is drawn and not offset under the loan’s terms. Ask about staged access and how interest is calculated.

If the purpose changes, tell the lender and obtain advice where relevant. Loan purpose can affect the product, assessment and tax treatment. Keeping separate records from the outset is easier than untangling mixed transactions later.

Compare the structure, not just the cash released

Possible arrangements include increasing the existing loan, establishing a separate split or refinancing. Availability depends on the lender and circumstances. Ask how each option changes the rate, remaining term, fees and security arrangements.

Moneysmart’s home-loan guidance encourages comparison of loan costs and features, not only the headline rate. An apparently convenient top-up can be expensive if it changes the pricing of a much larger existing balance. Request the before-and-after repayment schedule in writing.

When more than one property is involved, ask exactly which properties secure each debt and what must happen if one is sold. Do not agree to a structure you cannot explain. Independent legal or financial advice may be worthwhile before linking major assets.

Watch the repayment term

Spreading a new expense across a long mortgage term can make the monthly amount look small while increasing total interest. Match the repayment plan to the purpose rather than automatically accepting the longest term available.

For example, borrowing for an item with a short useful life and repaying it over decades can leave the debt outstanding long after the item is gone. Ask for a separate shorter-term repayment illustration. Compare the total amount paid, not just whether the first instalment fits.

If refinancing also restarts the existing mortgage term, compare it with keeping the original remaining term. Our refinancing-cost guide explains why switching expenses and term changes belong in the same calculation.

Understand what is at risk

Using equity converts part of the ownership value into additional borrowing. If property prices fall, the debt does not fall with them. If the funded investment loses money, the lender still expects repayment of the home-secured loan.

Do not rely on future capital growth or a later refinance as the only exit plan. Consider what would happen if income fell, an investment remained vacant or a renovation ran over budget. Keep enough flexibility to respond without immediately needing another loan.

Tax outcomes require separate advice. A loan secured against your home is not automatically personal or deductible based on the security alone. Ask a registered tax adviser about the intended use and record-keeping before mixing purposes.

Allow for costs before allocating the proceeds

Ask whether fees are paid separately or deducted from the released funds. If the approved increase is $100,000 and $2,000 of applicable costs is taken from it, only $98,000 reaches the planned project. Those figures are hypothetical, but the distinction prevents a funding shortfall on the day a payment is due.

Confirm when funds become available and whether the lender requires invoices or staged payments. Do not promise a supplier immediate payment based only on a preliminary approval. Retain a written schedule that matches the funding arrangement to the actual project commitments.

Take a completed worksheet to the lender

Bring the estimated value, current statements, limits on other secured facilities, purpose of the funds and a realistic household budget. Ask the lender to replace each estimate with its assessed figure and explain any difference.

Record the maximum approved amount, the amount you intend to use, upfront costs and repayments. Those are four different numbers. Check the offer’s expiry and conditions before committing to a purchase or work contract.

General information checked 29 September 2026. The examples are illustrative and do not assess your eligibility, borrowing capacity or tax position. Obtain personal advice where needed before increasing debt secured against your home.