Each person has a different lifestyle. To maintain a good lifestyle lot of financial planners, go with $100k a year for a couple, means $50k for one person. However, this has been a very traditional approach this approach is suited for industrial age era not for modern time (information age)
Traditional approach is you work till 65, keep making small savings in your retirement funds. By the time you retire you should have about $500k in your investments. These investments will give you a yield of about 5%, so you will get about $25k a year. You will also be eligible for Super, may be one investment property so roughly you will get about $50k a year.