Brahmanda Purana, like all other Purānas, is encyclopedic in character. The Purana is called Brahmanda since it gives explanation of the real state of affairs about the universe. It deals with topics such as Cosmogony, Religion, Philosophy History, Geography and Astronomy. The English translation of the Brahmanda Purana is by Dr. G.V. Tagare and the pdf format for free is provided by Internet Archive Open Source Books.
You can download Brahmanda Purana here at the archive.org - Brahmanda Purana in English in Pdf format
Please note that you will need pdf reader to access and read the Purana.