This site is being deprecated.
Please see the official X‑Plane Support page for help.
The full world scenery installation of X-Plane 10 is nearly 70GB. The smallest install size, with no scenery, is between 5.5 & 6GB.
You can install "tiles" of scenery one at a time through the installer. The squares represent 10° lat by 10° long of scenery and each square may be different sizes, depending on how dense the scenery is. Tiles with a lot of water, for example, will be much smaller. Range appears to be anywhere from 1mb to ~500mb per tile.
This site is no longer being actively maintained.