Your home equity is not the number you think it is. The figure that matters when you refinance is usable equity, and it is almost always smaller than the headline amount.
If you are weighing up a refinance home loan to renovate, consolidate debt or unlock equity for the next property, the maths below takes about five minutes. It also stops you from planning around money a lender will not hand over.
How Do You Calculate Home Equity?
Total home equity is your property's current value minus the balance of your loan. If your home is worth $800,000 and you owe $400,000, your total equity is $400,000.
That part is easy to do on the back of a coffee receipt. The harder part is the value. Online estimates and neighbours' sale prices are useful starting points, but a lender will order its own property valuation, and that is the figure they will use. Treat your estimate as a rough guide, not a promise.
Total Equity vs Usable Equity: Why the Numbers Differ
Usable equity is the amount of equity below a lender's typical maximum loan-to-value ratio, usually 80% of your property's value minus your current loan balance. It is an estimate only. How much you can actually borrow depends on the lender's valuation, its policy and whether you pass its serviceability assessment. Many lenders use 80% as the limit because borrowing above it often brings Lenders Mortgage Insurance (LMI).
Using the same figures, 80% of $800,000 is $640,000. Subtract the $400,000 you owe and your usable equity is $240,000, not $400,000. Lenders keep a buffer between your loan and your home's value, which is why the usable number is always lower.
If the result comes out negative, your loan already sits above the 80% mark. In that case you have no usable equity yet, although paying down the loan or a rise in value can change that.
What a Lower Valuation Does to Your Usable Equity
A small drop in valuation takes a bigger bite out of usable equity than you might expect. The reason is that the lender applies 80% to the new value, but your loan balance stays exactly where it was.
Consider an owner who owes 55% of their home's estimated value and wants to unlock equity for a deposit on the next property. Using their own estimate, usable equity looks like 80% minus 55%, or 25% of the home's value. Then the lender's valuation comes back 5% lower than their estimate.
On the lower value, 80% becomes 76% of the original estimate. Subtract the 55% still owing and usable equity falls to 21%. That is a 5% dip in value producing a 16% fall in usable equity (from 25% to 21% of the original estimate).
An owner who ran this scenario before applying could size their plans to the lower figure and choose a smaller loan amount. A good habit is to calculate your usable equity at your estimate and again with the value reduced by 5%, then plan around the lower result.
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Refinance Home Loan Trade-offs When You Release Equity
Releasing equity gives you cash or borrowing power, but it increases your loan amount, so you will owe more and pay more interest over time. That is the main trade-off, and it applies whether the funds go to renovations, debt or another property.
A larger loan can also push your loan-to-value ratio closer to 80%, which may limit your options with some lenders. Switching lenders can also involve costs such as discharge or application fees, depending on your current lender and the new one. Ask for these upfront so you can weigh them against any saving from a lower interest rate.
If you are only chasing a lower rate, you do not have to release a cent. You can refinance for the same balance and keep your equity untouched.
Using Equity for an Investment Property
Equity can be used as the deposit for an investment property, and the borrowing is often set up as a separate loan so it stays clear what the money was used for. The main risk is that you are now borrowing against your home to buy an asset that may not rise in value, and you still need to cover repayments if the property sits vacant.
The purpose of the borrowing can affect how interest is treated at tax time, so speak with your accountant before you set up the structure. Our investment loans page covers how these loans are typically structured, and the borrowing capacity page explains how lenders assess whether you can afford the extra debt.
When to Refinance: Fixed Rate Expiry and Other Triggers
The most common time to refinance is when your fixed rate period is ending, because your loan usually reverts to a different rate once the term finishes. That is a good moment to compare options, since you may be able to move to a lower interest rate or change your loan features.
Other triggers include a rise in your property's value, a change in income, or a loan that no longer suits how you use it. If your fixed term is close to ending, our fixed rate expiry page explains what to expect. For a wider look at moving lenders, see our refinancing overview.
A loan health check is a sensible first step. It compares your current rate and features with what else is available, and it gives you a clear picture of your equity before you commit to anything.
Frequently Asked Questions
How do I calculate usable equity in my home?
Multiply your property's value by 80%, then subtract your current loan balance. For example, a home worth $800,000 with a $400,000 loan has $240,000 of usable equity. This is an estimate only. Your lender's valuation, policy and serviceability assessment will determine how much you can actually borrow.
Why is usable equity lower than total equity?
Lenders keep a buffer between your loan and your home's value, and many use 80% as their limit. Borrowing above it often brings Lenders Mortgage Insurance.
Can I refinance without releasing equity?
Yes. You can refinance for the same balance to move to a lower interest rate or change your loan features, without taking out extra funds.
Does a lower valuation affect how much I can borrow?
Yes. Your loan balance stays the same while the 80% limit applies to the lower value, so usable equity can fall by a larger percentage than the valuation did. It helps to calculate your figures at a slightly reduced value before applying.
