A house room size can be translated to Unit Size by figuring at about one-third. If your house room size is 10x15 (150 square feet) then a 5x10 (50 square feet) unit would likely work for you. A 15x15 room would need a 10x10. Two 14x14 rooms would need a 10x15. A 3-bedroom home can generally fit in a 10x20.
Use climate control/comfort building units if you need something not to freeze or melt. This would include paintings, pictures, electronics, wine, high-value clothing, collectibles, and furniture. The next best thing is outdoor units with insulated ceilings. They are about 20 degrees cooler in summer and we have some of those also. Storing near the floor is about 20 degrees cooler than near roof, but floors can give off moisture (very normal). It is wise to put things in sealed bins and put plastic over top and underneath.
Use 5x10x8h Size - 400 cubic feet if...
you hauled with a pickup, van, or 6x10 trailer
you are moving a small room
you emptying a closet
you need a handy place to store seasonal decorations
Use 10x10x8h Size - 800 cubic feet if...
you hauled with a 8x12 trailer or truck or smaller
you are moving one or two rooms
you need a half car space of a garage
you could fit a 5x10 but need to add or remove items frequently
Use 10x15x8h Size - 1200 cubic feet if...
you hauled with a 8x16 trailer or truck
you can fit a 10x10 but can't stack that high
you can fit a 10x10 but need to add/remove items often
you need most of one garage car space
you are moving 2-4 rooms of goods
Use 10x20x8h Size - 1600 cubic feet if...
you hauled in a 26 foot truck
you need a full one car garage of space
you can fit a 10x15 but can't stack that high
you will be adding or removing items frequently
you are moving a 3 bedroom house
you are moving 6-8 rooms of goods
you want to park a car or trailer inside
Use 10x30x8h Size - 2400 cubic feet if...
you hauled in a 26 foot or larger truck
you need a 2-car garage of space
you are moving a 4 bedroom house
you are moving 7-9 rooms of goods
you want to park a boat/car/pickup or trailer inside
you could fit a 10x20 but want room to maneuver
you want roll-up doors on both ends for easier access
Use 15x50x13.5h if...
you want to unload a semi-sized house load
you are moving a 4+ bedroom house and garages
you want to protect your large RV or special vehicles from hot sun/hail
you need to store your stage equipment/props/gear
you want more security than nearly any other option