According to Official Guinness Records,
The largest free floating soap bubble (indoors) is 19.8 metres³ (699.2 ft³), and was achieved by Graeme Denton, a.k.a Marty McBubble (Australia), at Lockleys Primary School, Adelaide, Australia, on 19 June 2017.Graeme Denton, a.k.a Marty McBubble attempted this record with the help of Professor Matthew Roughan of The University of Adelaide who calculated the size of the bubble.
For a complete list of 2017 records, please visit 2017 Guinness Records in Australia.