Commercial Loan Calculator

By Mansour Soltani, Commercial Broker. Updated September 2026 with 2026-27 stamp duty rates.

A commercial loan gets assessed on different rules from a home loan. The lender wants a bigger deposit, the term is shorter, the rate is higher, and the question that decides the deal is not really your income. It is whether the rent from the property can carry the interest on its own.

This calculator works through all of that for a shop, office, warehouse or medical suite anywhere in Australia. Put in the price, the rent and your loan terms. It shows the cash you need on settlement day, including the stamp duty and GST most people forget, then what you repay while you are interest only and after. It also shows how many times the rent covers the interest, which is the test the bank will run.

How a commercial loan is different

Four things change the moment the property is not a home.

• The deposit. Most lenders stop at 65 to 70 per cent of the value, so you need 30 to 35 per cent of your own money plus costs. A few will go higher for a strong tenant on a long lease, but that is the exception.
• The term. Fifteen to twenty-five years is normal. Thirty is rare. A shorter term pushes the principal and interest repayment up.
• The rate. Commercial rates sit above owner-occupier home loan rates, and each deal is priced on its own risk.
• Reviews. Many commercial loans come up for review every one to three years. The lender can change the rate or the terms at each review, so the rate you start on is not locked for the life of the loan.

The number lenders actually decide on

For an investment property the lender looks at the interest cover ratio. That is the rent left after vacancy and the costs you pay yourself, divided by the year’s interest. Most lenders want at least 1.5, meaning the rent covers the interest one and a half times over.

Take the example already loaded in the calculator. A $1,200,000 property with a 30 per cent deposit leaves a loan of $840,000. At 6.85 per cent the interest is $57,540 a year. The rent is $96,000; knock off 3 per cent for vacancy and $6,000 of outgoings and you are left with $87,120. That covers the interest 1.51 times, so it just clears the bar.

Now look at the rate rise table under the results. At 7.85 per cent the cover drops to 1.32. At 8.85 per cent it is 1.17. The property has not changed, but at the next review a lender could say it no longer fits their rules. That is why you should know which row you could live with before you sign.

Working it backwards, with your income

The calculator also runs the test in reverse. It works out the rent the property needs to reach 1.5 on its own, then again with your spare income counted. Spare income is your other income after tax, less your living costs and other loan repayments.

In the example the property needs $95,165 a year of rent to pass on its own, just under the $96,000 it earns. Add $60,000 a year of spare income and the rent it needs drops to $33,309. Not every lender will count your income, and some only count part of it, so treat the lower figure as the best case and the higher one as the safe one. Both are shown again at a rate 2 per cent higher, because that is what the next review could look like.

Stamp duty on commercial property, state by state

Duty on commercial property does not follow the home buyer rules, and two places charge nothing at all. On a $1,200,000 purchase in 2026-27 the calculator gives:

• NSW: $48,187. The general scale applies. The premium rate over $3.87 million only hits residential land, so it never applies to a commercial purchase.
• Victoria: $66,000. You pay duty on the first sale after 1 July 2024. The property then moves into the Commercial and Industrial Property Tax and later buyers pay no duty.
• Queensland: $49,525 at the full rate. The home concessions do not apply.
• Western Australia: $52,916 at the general rate, not the lower residential rate.
• South Australia: nothing. Duty on commercial and industrial land was abolished on 1 July 2018.
• ACT: nothing up to $2,100,000. Above that it is a flat 5 per cent of the whole price.
• Tasmania: $49,185.
• Northern Territory: $59,400.

Duty is charged on the higher of the price and the market value. Foreign buyer surcharges and land tax are extra and are not included here. Work out the land tax on the land tax calculator; in the ACT commercial property pays none.

GST: money you get back, but have to find first

Commercial property is usually sold plus GST. On a $1,200,000 price that is another $120,000 due at settlement. If you are registered for GST you normally claim it back on your next activity statement, but you still have to fund it on the day. Some lenders will lend it to you for a short time and some will not.

If the property is sold as a going concern, with the tenant and lease staying in place, the sale can be GST free and that $120,000 never leaves your account. Pick the GST option in the calculator that matches the contract and watch the cash figure change. Check the GST treatment with your accountant before you exchange.

Interest only, and the jump when it ends

A lot of commercial loans start interest only for a few years. In the example that is $4,795 a month. When the three years run out you start paying principal over the seventeen years that are left, and the repayment goes to $6,980.78. That is a jump of $2,185.78 a month. The calculator shows it on its own line so it does not catch you out.

Questions people ask

How much deposit do I need for a commercial property?

Plan on 30 to 35 per cent of the price, plus stamp duty, GST if it applies, and legal, valuation and lender fees. On the example that adds up to $540,187 in NSW.

Can I use my home as security instead of a cash deposit?

Often, yes. Many buyers use equity in their home or another property to cover the deposit. The lender then takes security over both, which is worth understanding before you agree to it.

Is the rate on a commercial loan fixed?

It can be fixed or variable, but either way the loan is usually reviewed every one to three years and the lender can reprice it then.

Does my own income matter?

Yes, especially if the rent cover is tight. Where the rent alone does not clear 1.5, a lender may accept it if your other income makes up the gap.

Want the background first? Read our guides to investing in commercial property in Australia and choosing a commercial lender. For a build rather than a purchase, use the construction loan calculator.

Estimates only, for general information. They are not an offer of credit or personal advice. Commercial lending is assessed deal by deal, so confirm the figures with a broker and your accountant before you commit.