The report, released on Tuesday by the Diversity Council Australia and University of Sydney Business School, found businesses were failing to properly measure the breadth of their talent's cultural background.

With no standardised approach, it said many Australian workplaces were resorting to asking employees about their country of birth.

DCA chief executive Lisa Annese said people don't realise how many elements cultural diversity covers.

"It is so much more than just where people in a workforce were born," she said.

"For example, an employee may be born in Australia, have Lebanese ancestry, speak English, Arabic and French, and identify as Christian.

"All of these have relevance to their experience of inclusion at work as well as the cultural capability they can bring to the organisation."

Almost half of Australians are born overseas or are second-generation Australians, according to the 2016 Census, and Ms Annese said the failure to understand cultural complexity was a missed business opportunity.

"Research shows engaging with these layers leads to enhanced organisational performance and profitability," she said.

"Added to this, we know the Australian 'multicultural market' has an estimated purchasing power of over AUD$75 billion per year."

The report guides businesses through how best to "count" cultural background, language and religion, and is based on consultation with 300 practitioners and a pilot survey of 1200 employees.

The University of Sydney's Dr Dimitria Groutsis, who spearheaded the project along with DCA's Dr Jane O'Leary, said many boardrooms did not reflect Australia's rich cultural diversity.

"Decisions are being made, resources are being deployed in the highest layers of our institutions and yet, the voices of our culturally diverse population are silent in these decisions and in the distribution of resources," associate professor Groutsis said.

"Our report offers a template to change all that and ensure Australia's diverse voices are heard."

Australian Associated Press