Principal Dan Reddiex said about 190 year 12 and 13 pupils were eligible to attend the ball, but only 35 couples had confirmed they would be going.
"Historically, there's a big rush at the last minute to get tickets.
That didn't happen this year, so we've had to postpone it."
The function was to have been held at the Savoy, in Dunedin, and the decision to postpone it was made partly on financial grounds and partly because of the size of the venue, he said.
"The Savoy is a big venue and, with only about 35 couples, it would have been a pretty soulless atmosphere.
"We simply didn't have enough people to make it financially viable."
Given the event was one of the highlights for the majority of senior pupils, Mr Reddiex was surprised at the lack of ticket sales - "I'm assuming it's due to tough economic times. I really don't know."
Tickets for the function cost about $150 per couple, which covered the band, the meal and the venue hire.
"But that does not include suit hire, flowers, limos ... The list goes on."
Kaikorai Valley College and Taieri College formals will be held at the end of next week, and principals Philip Craigie and Christina Herrick say the event is proving to be just as popular as in previous years.
Kaikorai Valley College's senior roll was lower than previous years, but the majority of pupils had confirmed they would be attending, Mr Craigie said.
There had been a "huge explosion" of senior pupils at Taieri College this year and the school was searching for a larger venue for its formal, Mrs Herrick said.
"There's no doubt the school formal is just as popular as it has been every other year," she said.
