According to the International Building Code, the ratio of female to male toilets depends on the type of building and building occupancy. Most occupancies require a 1:1 ratio, but assembly uses like stadiums, pools, amusement parks can require up to a 2:1 ratio of female to male toilets. The ratio is set by codes and varies from jurisdiction to jurisdiction. You should look up to the regulations governing plumbing in your jurisdiction. The ratio differs for hotels, businesses, hospitals, stadiums, gas stations, churches, theatres, etc. Most American state laws vary between 1:1, 3:2, and 2:1 ratios.