4.38GB
DVDs are 4.7GB where GB = 1,000,000,000 bytes
But in computer terms where GB = 2^30 = 1073741824, you get 4,700,000,000/1073741824 = 4.3772161007 GB
roughly 4.38GB
You can squeeze it up to 4.4 but I try to keep it under 4.38 since the outer edges of DVDs tend to be less reliable.