5x10 unit typically holds a couch, chair, chest of drawers or dresser, box spring and mattress set, or up to 84 standard file size boxes.
10x10 unit typically holds furniture from a small one-bedroom apartment (2-3 rooms) without appliances. Can store up to 168 file size boxes.
10x15 Unit typically holds furniture from a two-bedroom apartment (3-4 rooms) without appliances or a one-bedroom apartment—or store up to 294 file size boxes. Can fit a small utility trailer.
10x20 unit typically holds furniture from a large two-bedroom apartment (5 rooms of furniture), or a small one-bedroom house with appliances. Can store up to 378 file size boxes. Can also fit a car.
10x25 unit typically holds furniture from a large two-bedroom house and appliances. Stores up to 504 files size boxes.
10x30 unit typically holds the contents of a three-bedroom home (6-8 rooms) and appliances. Or, up to 588 file size boxes.
10x35 unit typically holds the contents of a Large four-bedroom home (7-10 rooms) and appliances. Or, up to 672 file size boxes.
For your convenience here is an image that may help you decide what will fit in a unit. Be aware this image is basic. One can get much more in a unit than what is being displayed.