Australian business calculators and tools

Questions these calculators answer

How do I check if an ABN is valid?

An ABN is valid when you subtract 1 from its first digit, multiply the eleven digits by 10, 1, 3, 5, 7, 9, 11, 13, 15, 17 and 19, add the results, and the total divides exactly by 89. That proves the number is well formed; it does not prove the business exists. ABN Lookup confirms registration.

What must an Australian tax invoice include?

An Australian tax invoice must say "tax invoice", show the seller's name and ABN, the date, a description with quantity and price of each item, the GST amount, and which items are GST-free. Once the total reaches $1,000 it must also show the buyer's name or ABN. A sale of $82.50 or less including GST needs no tax invoice unless asked.

What should an Australian quote include?

A good quote states who you are (name and ABN), who it is for, the date, an itemised description of the work with prices, whether GST is included, how long the quote is valid, the payment terms and what is not covered. A quote is an offer, not a tax invoice, and you issue a tax invoice once the work is done or paid for.

How do I choose and register a business name in Australia?

Pick a name, check it is not already registered on ASIC's business names register, not identical to an existing company name and not a registered trade mark, then register it with ASIC if you trade under a name other than your own. A business name is not the same as a trade mark, and registering one does not give you the exclusive right to use it.

How do I check if a TFN is valid?

Multiply the nine digits by the weights 1, 4, 3, 7, 5, 8, 6, 9 and 10, add the results, and the total must divide by 11. The commonly used test number 123 456 782 gives 253, which is 11 × 23, so it passes. A pass shows the number is well formed, not that the ATO issued it.

How do I check if an ACN is valid?

Multiply the first eight digits by 8, 7, 6, 5, 4, 3, 2 and 1 and add them. The ninth digit must equal 10 minus the last digit of that total, counting 10 as 0. For 004 085 616 the total is 84, so the check digit is 6, which it is. A pass proves the number is well formed, not that the company exists.

What is the difference between markup and margin?

Markup is profit as a percentage of cost; margin is profit as a percentage of the selling price. A $100 item sold for $150 has a 50% markup but only a 33.3% margin, because the same $50 of profit is measured against a bigger number. To get a 50% margin you need a 100% markup.

How do I calculate gross profit?

Subtract the cost of goods sold from sales, both excluding GST. $250,000 of sales with $140,000 of cost of goods gives $110,000 of gross profit, a gross margin of 44%. After $70,000 of running costs the net profit is $40,000, or 16% of sales.

How do I calculate my break-even point?

Divide fixed costs by the contribution per unit, which is price less variable cost. With $60,000 of fixed costs and $80 price against $35 variable cost, each sale contributes $45, so you break even at 1,334 units. To also earn $15,000 of profit, you need 1,667 units.

How much should a contractor charge per hour?

Add your target income, business costs and retirement saving, then divide by the hours you can really bill. $100,000 target income, $12,000 of costs and $12,000 of retirement saving, over 1,320 billable hours (44 weeks at 30 hours), gives $93.94 an hour excluding GST.

How do I calculate a discount?

Multiply the price by the discount as a decimal and subtract it. $250 with 30% off is $175. A further 10% off that price takes it to $157.50, a total saving of $92.50, which is 37% off rather than 40%.

How do I calculate ROI?

Divide the gain by the amount invested. $20,000 that grew to $31,000 and paid $1,500 of income made a gain of $12,500, an ROI of 62.5%. Over 5 years that is 10.2% a year, which is the figure to compare with other investments.

How do I work out an invoice due date?

Add the number of days in the payment terms to the invoice date. An invoice dated Thursday 12 November 2026 on 30-day terms is due on Saturday 12 December 2026. Under 30 days end of month terms the 30 days start from the end of the invoice month, so the due date is later.