Mr Weatherill waded through cheering Labor supporters at the West Adelaide Football Club on Saturday night to concede election defeat.

"I'm sorry I couldn't bring home another victory, but I do feel like one of those horses that has won four Melbourne Cups," he told the party faithful.

"I think the handicapper has caught up with us on this occasion."

Reflecting on Labor's lengthy stint in power, Mr Weatherill said he was proud of how the party had grown the state's economy and helped Adelaide become a vibrant city.

He also spoke of their "extraordinary international leadership" in renewable energy.

But he was careful not to take all the credit, heaping praise on his predecessor Mike Rann.

"What we managed to achieve here in this state, and I had the privilege to continue, has much to do with his leadership and his drive in those extraordinary circumstances that took him to government back in 2002," he said.

It wasn't all glum news at the Labor function, with many candidates expected to retain their seats.

Among them was Port Adelaide MP Susan Close, whose mother Elizabeth and brother Stephen joined the event after spending the day handing out campaign fliers.

"I'm really happy for Susan. She's worked so hard for her electorate and so hard as Minister for Education," her brother said.

Treasurer Tom Koutsantonis said it was a testament to Labor that the Liberal party were expected to win only 24 seats in the 47-seat house.

Labor has lost some of its 23 seats, but the final result is not yet known. It's projected they'll end up with 18 seats.

"It's a remarkable result after 16 years, that the Libs might just crawl over the line," he told AAP.

Long-time Labor supporter Roger Zubrinoch was among those feeling a little more bruised, although he said he had known it would be a tough fight after a "brutal" redistribution of electoral areas.

"It doesn't make it any better," he said.

Mr Weatherill tried to curb such disappointment in his address, in which he also thanked South Australians, by urging Labor supporters to keep their heads high and pledging the party would come back.

"As we leave government, we leave government united, strong and with a real sense of purpose," he said.

He also gave a small insight to what life beyond politics will mean for him in promising to be better to his family members and making a promise to his two young daughters.

"You're about to get your daddy back," he said grinning.