The ATAR (Australian Tertiary Admission Rank) calculator is an online tool used to estimate a student's ATAR score based on their predicted or actual marks in their senior secondary school subjects. Different calculators exist for different states and exams, such as the NSW HSC or the VCE in Victoria. These calculators use historical scaling data and performance statistics from the last several years to provide an estimate, which is usually a guide rather than a precise number. For example:

• The ATAR Compass by UAC estimates the ATAR for NSW HSC students based on predicted or actual HSC marks.
• Deakin University's ATAR Calculator estimates the VCE ATAR using the scaling report from VTAC.
• Other calculators, like those from Talent 100, Matrix Education, and ReviseOnline, offer estimates for various state exams using past scaling data.

These calculators require users to input their subject choices and marks, often including English and other eligible courses, and then compute scaled scores to estimate the overall ATAR. The actual ATAR depends on the scaling applied the year the student receives results, so estimates may vary. Let me know if details about a specific ATAR calculator or state system are needed!