Board Thread:Questions and Answers/@comment-204.137.236.135-20141116062053/@comment-1173941-20141226194545

The web novel for SAO wasn't split into volumes, the same way the light novel was.

However, Alicization was split into 8 chapters (with some interludes, and multiple prologues/epilogues), with chapters 1-5 being compressed into Volume 9, and Chapter 7 is Volume 11-14. (Volume 10 is mostly stuff that wasn't in the web novel, except for the bit at the end, which in the web novel was an interlude if I recall correctly.) WN Chapter 8 is also a bit longer than Chapter 7. Volume 15 has a shortened version of Chapter 6, and what use to be an interlude in the web novel.

So by that estimate, 3-4 more books at the very least should be expected.