This is a conservative estimate, as the executive summary states:
Extending marriage to Australian same-sex couples would boost the country’s economy by $161 million over three years. This estimate is based on a projection that 54 percent (or 17,820) of Australia’s approximately 33,000 same-sex couples would marry. Tasmania, in particular, stands to claim a large share of that $161 million should it become the first state to allow same-sex couples to marry. In addition to marriages by Tasmanian couples, an estimated 15,236 couples would travel from out-of-state to marry in Tasmania, resulting in an economic gain of $96 million or more for the state. The figures in the report draw upon recent surveys, estimating the total number of Australian same-sex couples and the number of same-sex couples interested in marriage. Notably, the estimates in the report are conservative compared to other estimates because they only include spending by resident couples. They do not include spending by wedding guests, or wedding or tourism spending by couples traveling to Australia to marry. One recent study that took this additional spending into account estimated an economic boost of $742 million.Come on, Australia! Don't you want 2011 US Open champion Sam Stosur to be able to legally marry her girlfriend?