Australian ABN Generator & Validator
Generate valid Australian Business Numbers (ABN) for software testing and development. Validate any ABN using the official weighted checksum algorithm — runs entirely in your browser.
For testing and development only. ABNs generated by this tool are mathematically valid but not registered with the Australian Business Register. Do not use them for tax invoices, business registration, or any purpose other than software testing and development.
Australian Business Number (ABN)
—
No additional info
Sample Australian ABNs
How to use it
- 1Click Generate to produce a random, mathematically valid ABN — 11 digits formatted as XX XXX XXX XXX.
- 2The tool displays the full ABN and explains how the weighted checksum was satisfied. Copy the number with one click.
- 3Switch to the Validate tab and paste any ABN to check whether it passes the official algorithm.
- 4Sample ABNs are pre-generated on load — copy any of them directly for quick test data.
Common use cases
- Populate a test database with valid-looking ABNs for integration tests on Australian business-registration forms.
- Validate user-submitted ABNs on the front end before sending data to a backend service.
- Demonstrate the ABN format and check-digit algorithm to developers new to Australian tax identifiers.
- Generate a batch of ABNs for UI stress-testing without accessing real business records.
- Teach or audit the ABN validation rule — watch which check fails and why for any given input.
Frequently asked questions
- What is an Australian Business Number (ABN)?
- An ABN is an 11-digit identifier issued by the Australian Business Register (ABR) to businesses and entities for tax and regulatory purposes. It is used on invoices, GST returns, and communications with the ATO. The first digit is always between 1 and 9; the remaining 10 digits can be any combination.
- How is an ABN validated?
- Subtract 1 from the first digit, then multiply the 11 digits by the weights [10, 1, 3, 5, 7, 9, 11, 13, 15, 17, 19] respectively. Sum the products. A valid ABN produces a sum that is exactly divisible by 89. This is the algorithm published by the Australian Business Register.
- Who needs an ABN?
- Any Australian business, sole trader, company, partnership, trust, or non-profit operating in Australia should have an ABN. It is required to issue tax invoices, claim GST credits, and interact with government agencies. Individuals may also obtain one for freelance or contracting work.
- What do the digits of an ABN mean?
- Publicly, the ABN does not encode specific information in its digits — they are assigned sequentially with the check-digit constraint. The ABN is derived from the 9-digit ACN for companies, or assigned independently for other entities. The structure itself is opaque; the checksum is what makes a number 'valid'.
- Is it safe to use generated ABNs for testing?
- Yes, as long as they are used only in test environments. Generated ABNs pass the mathematical check but are not registered — they have no associated business name, GST registration, or entity. Any system that validates ABNs against the live ABR lookup will correctly reject them as unregistered.
Try next
Australian ACN Generator & Validator
Generate and validate Australian Company Numbers (ACN) using the official check-digit algorithm. For testing and development — runs entirely in your browser.
Australian Tax File Number (TFN) Validator
Validate Australian Tax File Numbers (TFN) — checks format and the official check-digit algorithm. No TFN generation to protect against misuse. Runs entirely in your browser.
Australian BSB Number Validator
Validate Australian Bank State Branch (BSB) numbers — checks the 6-digit format and identifies the bank from the first two digits.