Every home loan advertisement in Australia shows you two percentages, sitting side by side. One is usually large and prominent. The other is smaller, sometimes tucked into a footnote, and easy to skim past entirely. Understanding the difference between them isn’t a nice-to-have. It’s the difference between correctly judging what a loan will actually cost you and getting caught out by a number that looked good on the surface.

Here’s what each figure actually measures, why they’re not the same thing, and how to use both properly.

The interest rate: what the money itself costs

The interest rate is the most familiar figure, and it measures exactly one thing: the cost of borrowing the money, expressed as an annual percentage. If you borrow $500,000 at a 5.89% interest rate, that percentage is applied to your outstanding balance to calculate the interest component of your repayments.

What the interest rate does not include is anything else attached to running the loan. Application fees, ongoing monthly or annual account fees, valuation fees, discharge fees down the track, none of that shows up in the interest rate itself. A lender could theoretically advertise an extremely attractive interest rate and load the loan with fees elsewhere, and the interest rate alone would never reveal that.

The comparison rate: the interest rate plus most of the rest

This is exactly the gap the comparison rate exists to close. ASIC’s MoneySmart service defines it as a rate that helps you work out the true cost of a loan, because it includes the interest rate along with most fees and charges relating to the loan, reduced to a single percentage figure (ASIC MoneySmart).

In other words, the comparison rate takes the interest rate as its starting point and adds in most of the additional costs a borrower would otherwise have to hunt down separately across a product disclosure statement. The result is a single number designed to let you compare two different loans, from two different lenders, on something closer to a genuine like-for-like basis.

This is precisely why the two figures can differ so much between products. A loan advertised with a comparison rate of 5.69% for the interest rate but 5.95% for the comparison rate is telling you something specific: roughly 0.26 percentage points worth of fees and charges are baked into that product, on top of the headline rate you initially saw.

Why you’re legally guaranteed to see both

This isn’t something individual lenders have chosen to adopt out of good faith. Displaying a comparison rate whenever an interest rate is advertised is a requirement under Part 10 of the National Credit Code, which forms Schedule 1 of the National Consumer Credit Protection Act 2009 (ASIC, National Credit Code overview). It applies to any credit provider advertising a fixed-term loan mainly used for personal, domestic or household purposes, which is exactly the category most home loans fall into.

The rule has a specific history behind it. Before a nationally consistent comparison rate regime came into force in 2010, lenders in different states operated under different disclosure rules, and there was no guaranteed mechanism forcing a lender to reveal the full cost of a loan upfront in one figure. A lender could advertise a headline rate that looked competitive while charging fees that only became clear once you were deep into the application process. The comparison rate requirement closed that gap by mandating a standardised, comparable figure alongside every advertised rate.

The standardised example hiding inside every comparison rate

Here’s where the comparison rate gets more complicated than it first appears, and it’s a detail worth understanding rather than skipping.

Every advertised comparison rate is calculated using the same fixed example, set out in Regulation 71 of the National Consumer Credit Protection Regulations 2010: a $150,000 loan over a 25-year term (Regulation 71, NCCP Regulations 2010). Every lender has to run this same calculation on this same hypothetical loan, which is exactly what makes the resulting figures genuinely comparable to one another.

The problem is that this standardised example rarely matches an actual borrower’s circumstances. Many home loans today sit well above $150,000, and 30-year terms are common. When a loan is larger and the term is longer, a flat annual fee represents a smaller share of the total cost than it does in the $150,000/25-year example. That means the advertised comparison rate can overstate how much fixed fees actually matter for a loan the size most people are taking out.

This is also where fixed-rate loans get particularly confusing. Because the comparison rate calculation runs across the full 25-year example rather than just your fixed term, the number assumes your loan reverts to the lender’s standard variable rate for whatever period remains after the fixed term ends. Two lenders offering almost identical fixed rates can display noticeably different comparison rates, purely because their assumed revert rates differ, not because one fixed rate is actually a better deal than the other.

What neither number tells you

Both figures, useful as they are, stop short of the full picture. ASIC’s own guidance notes that a comparison rate does not capture every cost, specifically excluding things like government charges (stamp duty, mortgage registration fees), and it only measures cost, not features like offset accounts or flexible repayment arrangements that might make a loan more valuable to you personally regardless of price (ASIC, National Credit Code overview).

Lenders Mortgage Insurance sits entirely outside both figures too. If you’re borrowing above 80% of a property’s value, LMI can add a five-figure cost to your loan, and neither the interest rate nor the comparison rate will show you that number anywhere.

How to actually use both figures

Use the interest rate to understand your month-to-month repayment cost. Use the comparison rate as your first filter for spotting whether a loan is carrying heavier fees than its headline rate suggests. Then go further than either number by checking it against your actual loan size and term, not the standardised $150,000/25-year example, and against features that matter to how you actually plan to use the loan.

Two loans with nearly identical comparison rates can behave very differently once you factor in your real numbers, your plans to make extra repayments, or whether you’re likely to refinance again within a few years. That’s the part neither figure was ever designed to tell you on its own.

If you’d like your genuine cost comparison worked out on your actual numbers, not the standard example every lender is required to advertise, get in touch with the hfinance team. We compare across 50+ lenders and can show you what a loan will really cost for your situation.

This article is general information only and does not take into account your personal financial situation or objectives. Speak with an hfinance broker before making any lending decisions.