Each exam is graded on a scale from A* to E.
Grade boundaries show the minimum number of marks you need for each grade.
They are decided by examiners and published on results day.
Qualifications Wales, which oversees Welsh exams, has said there is still a risk that performance in some subjects has not fully recovered since the pandemic.
So, it will use statistics to help set the grade boundaries, external, to prevent marks dropping significantly below 2019 levels.
In England and Northern Ireland, the way boundaries are decided has returned to normal.