There is no single IELTS score for 'an Australian visa'. The requirement depends on your visa subclass and sometimes your points claim.
1. English levels in skilled migration
Skilled visas use three levels: Competent English (IELTS 6.0 in each component), Proficient English (7.0 in each) and Superior English (8.0 in each). Higher levels earn more points in the points test.
2. Student visas
Student visa English requirements vary by course and provider, and are often set around an overall band with minimums for each component. Your institution and the Department of Home Affairs publish the exact requirement.
3. Other visa types
Partner, employer-sponsored and professional registration requirements all differ. Check the specific visa page.
4. Test validity
English results are valid for a limited time for visa purposes. Check how recent your result needs to be.
5. Why one band can matter
Because minimums apply to every component, a 5.5 in Writing can block an otherwise 7.0 result. That is why targeted skill coaching matters.
The bottom line
Always verify against the Department of Home Affairs website before booking a test, since rules change.
Test rules and score requirements change. Always confirm current details with the official test provider or immigration authority.