More than 65,000 year 12 students in NSW will receive letters from today explaining the change. The university entrance rank will change its name to the Australian Tertiary Admission Rank, in line with other states which - apart from Queensland - will also adopt the ATAR name.

NSW is the only state with a top university admission rank of 100, the others being pegged at 99.95.

Andrew Stanton, managing director of the Universities Admissions Centre, said ATAR rankings would be higher than equivalent UAI ranks which may push up course entry scores at universities. For example, a UAI of 60 would convert to an ATAR of 63.4, a UAI of 93 would be 93.55 and a UAI of 99 would be 99.05.

Mr Stanton said there was no need for students to worry about the change as it would make no difference to the way their marks were scaled or to their chances of gaining entry to preferred university courses.

Larissa Treskin, the principal of James Ruse Agricultural High, which last year produced eight students with UAIs of 100, said she was sorry other states did not round up their top university entrance rank to 100.

"I'm disappointed the top marks were compacted down rather than up," she said.

"I think emotionally, for this year's students, it is a goal that has been snatched away."

Daniel Swain, who received a UAI of 100 in last year's HSC, said it felt weird to be one of the last students to get the top rank.

Mr Swain, who completed his HSC at Smiths Hill High in Wollongong, needed a UAI of 83 to get into his Arts course at the University of Sydney.

He said friends in Victoria who had scored 99.95 had celebrated the same way as NSW students who received 100. "They still call it the perfect score. I think other people, like employers, think 100 sounds more impressive."