Hello,

CUET merit score is decided from your CUET exam marks.

Each university first selects which subjects are required for a course.
Then they take your marks from only those subjects.

If marks are in percent, they are added or averaged as per the university rule.
If marks are in NTA score, they use that score.

Formula is usually:
Merit Score = Sum of marks of selected subjects

After this, colleges prepare a merit list.
Higher score means higher chance of admission.

Hope it helps!