According to Official Guinness Records,
The largest flag draped measured 101,978 m² (1,097,682 ft²) and was achieved by Moquim Al Hajiri (Qatar) of Brooq Magazine (Qatar), in Doha, Qatar, on 16 December 2013.
The dimensions of the flag are: 509.97 x 199.97 m (1,673 ft 1.5 in x 656 ft 0.83 in).
For a complete list of 2013 records, please visit 2013 Guinness Records in Qatar.