Publicans say they would lose 87% of standing capacity if two-metre social distancing is introduced when bars reopen.
Their representatives say many pubs will only be able to function if the one-metre World Health Organization guideline is adopted.
The Licensed Vintners Association, which represents Dublin publicans, and the Vintners' Federation of Ireland, which represents the rest of the country, commissioned a report on the effects of social distancing.
It found that when the layout of a typical bar was taken into account, the two-metre social distancing rule would reduce capacity by up to 87% of standing customers and 66% of those seated.
If WHO guidelines were applied, standing capacity would drop by 50% while seated capacity would be reduced by 35%.
LVA Chief Executive Donall O'Keeffe said pub businesses have to fully grasp the commercial challenges they will face.
"The WHO requirements will still significantly reduce capacity, but they will at least allow more pubs and other hospitality businesses to be capable of trading in the shorter term. But that is a decision for the Government and the public health officials," he said.
Pubs around the country are due to reopen on 10 August.