Business groups say the New South Wales Government's decision to grant the people of Sydney a public holiday when the Asia-Pacific Economic Cooperation (APEC) summit is held later in the year will cost businesses around $320 million.

They concede it is a necessary move.

The one-off public holiday on Friday, September 7 will only apply to Sydney.

The NSW Business Chamber says it is pleased it was not extended to the whole of the state, as first proposed.

The chamber's spokesman Paul Ritchie says given the disruption the APEC summit will cause, the public holiday is probably justified because the city will be effectively closed.

"Having said that, there are costs, $327 million for business," he said.

Mr Ritchie has urged people to utilise the long weekend and get out of sydney.

"We shouldn't use this an an excuse to complain, but rather as an opportunity to promote other areas of the state," he said.

The Sydney Chamber of Commerce says despite the cost to business, there will be long term benefits from the summit.