Mr Thornton said there were more than one million entries into individual NCEA standards this year and 120 exam sessions.
He said Level 1 English was the year's largest exam, with 47,200 students sitting the exam this Wednesday morning.
The smallest was New Zealand Scholarship Latin, with 29 students sitting the exam on December 2.
A number of students were sitting exams at more than one level, he said.
A team of approximately 1,750 markers will mark all papers by Christmas, and NCEA results are expected to be released online from the middle of January, Mr Thornton said.
2014 Entries:
-- 62,101 students entered at Level 1
-- 56,190 students entered at Level 2
-- 39,843 students entered at Level 3
-- 10,448 students entered in 27 New Zealand Scholarship subjects.