This year, 50 per cent of students will complete the tests online as part of a three-year transition away from paper-based tests.

Each year students in Years 3, 5, 7, and 9 complete testing in five key areas - reading, writing, spelling, grammar and punctuation, and numeracy.

Students across the Central West will begin their NAPLAN tests on Tuesday, with some doing the online version and others using the paper-based tests.

Denison College principal Craig Petersen praised the introduction of the online tests.

"The online NAPLAN is a step in the right direction, it adjusts the questions as the student progresses," he said.

"It increases or decreases the complexity based on the individual student's capabilities.

"It'll challenge the more able students and give a clearer picture of what challenges students are having."

All but one NAPLAN test at St Mary's Catholic Primary School in Orange will be undertaken online this year.

Year 5 students will complete all their tests online, while Year 3 students will undertake all tests, with the exception of writing, online.

St Mary's co-principal Kerry Maher said students have become very familiar with the tests.

"I really think that the students have become very used to doing NAPLAN each year, it's almost been built into the fabric," she said.

"They're very familiar with the testing process so I don't think they're feeling fear."

Headmaster Craig Mansour from Macquarie Anglican Grammar School in Dubbo urged students and parents not to put too much pressure on the tests.

"Students should approach NAPLAN like they do anything else and just do their best because that's all we can ask for," he said.

"The less stress we put on students and NAPLAN the better."

Mr Mansour said NAPLAN was not an entire measure of who students are and how they perform

"Education is a measure of the whole child and that includes music, sport and extracurricular," he said.

"We as a society have narrowed our focus so much that we have lost our holistic focus of education."

NSW Teachers Federation country organiser Kelly Anderson said NAPLAN test results were not being used how they were intended.

"It's supposed to be an indicator that a school might need some different resources in particular areas," she said.

"There's undue pressure that's been put on kids.

"It's a snapshot of a child's progress at a give time, it's not the be all and end all."

NAPLAN online means more precise information about what a student knows and can do, Australian Curriculum, Assessment and Reporting Authority CEO David de Carvalho says.

He said the online testing process is also a more engaging experience for students.

The transition to online will be a three-year process.

Last year, 15 per cent of students took the tests online and in 2019 that number has grown to 50 per cent.

"One of the big benefits of NAPLAN online is that it uses a 'tailored test design'," Mr de Carvalho said.

"This means the test adapts to student responses in real time and presents students with questions that are more suited to their test performance."