OzCLO 2023 dates

The first round will be held online on Wednesday, 1 March 2023. The competition is held at the same time across Australia – the specific times for each state time zone are listed in the table below.

StatePreparation TimeCompetition Time
ACT1:30 – 2:30pm2:30 – 4:30pm
NSW1:30 – 2:30pm2:30 – 4:30pm
NT12:00 – 1:00pm1:00 – 3:00pm
QLD12:30 – 1:30pm1:30 – 3:30pm
SA1:00 – 2:00pm2:00 – 4:00pm
VIC1:30 – 2:30pm2:30 – 4:30pm
WA10:30 – 11:30am11:30am – 1:30pm

The second round, for the top-scoring teams from the first round, will be held offline on Wednesday, 22 March 2023.


The first round is a two-hour contest. Students compete in teams of four. Each team enters their team’s solutions on one computer. Teachers are given access to a pdf copy of the problem set an hour before the competition begins for students, and should give each student a printed copy to work on.

For further information on the format of the competition, please check our FAQ page below.

Visit FAQ


Registration will open from Monday January 16 to Friday February 24 2023. The cost of registration in 2023 will be $40 per team. For teams that register after the closing date, we will be charging a Late Fee of $20 per team.

Please note that only teams that are based at a school may participate, and only teachers may register their teams.

Register here