According to ANZ senior economist Cherelle Murphy, the economic benefits of marriage equality related to weddings alone would be $650 million in the first 12 months.

That is a conservative estimate, assuming only half the gay couples who want to wed manage to do so within 12 months.

According to the 2016 Census, there were nearly 47,000 same-sex couples living together in Australia.

A 2010 study by the University of Queensland found half of such couples would choose to marry, if possible.

That gives a total marrying pool of around 24,000 gay couples. Assuming an average wedding spend of $54,000, that yields total spending of $1.3 billion.

This would deliver a huge boost to Australia's $6.3 billion wedding industry, Ms Murphy predicts.

"The wedding spend by same-sex couples could be higher than the existing average, given their family incomes are on average higher than opposite-sex couples," she said.

Florist Emily Michele Smith, the owner of Boutierre Girls, is among those expecting a pick up in business if same-sex marriage is legalised.

"Most of the weddings are held overseas at the moment, like in New Zealand," Ms Smith said. "If they were held here in Australia I would definitely get more business."

Smith, whose wedding packages start from $5000 in Sydney and $8000 in Melbourne, says she has already decorated three gay civil ceremonies, and does not expect much difference between gay and straight wedding styles.

"One of them I didn't even know it was a gay wedding. They're no different to anyone else getting married."

However lesbian weddings could come with a double boost. "Sometimes the girls would like a bouquet each and I've seen some girls walking down the aisle together."

The head of the Tourism and Transport Forum, Margy Osmond, is predicting an added boost if thousands of foreign couples choose Australia as the scene for their dream destination wedding.

"The Australian tourism sector is champing at the bit to unlock the pink dollar potential of same-sex weddings," Ms Osmond said.

"In places such as tropical north Queensland, where the tourism industry has been recently hit hard by natural disaster and the slowing of the resources industry, the pink dollar could be somewhat of an economic saviour."

Ms Osmond pointed out that wedding spending was not just limited to brides and grooms, but also included money spent by wedding guests.

"The wedding economy casts a huge net, with the average wedding seeing a pretty significant amount of cash being spent on not just things such as catering, honeymoons and accommodation, but also on things such as tours and eating out."

In addition to wedding dollars, ANZ predicts the legalisation of same-sex marriage would also bring other indirect economic benefits, potentially boosting productivity through lower levels of stress and mental health problems if gay couples feel more accepted by society.

The chief executive of the Business Council of Australia, Jennifer Westacott, who has been in a same-sex relationship for 30 years, on Wednesday issued a personal statement welcoming the "yes" vote.

"Marriage equality has always been about respect and acceptance; the resounding 'yes' vote today is a victory for all those who have felt like outsiders for so long."