Not sure what size you need? 

If this is for household items, err on the side of "bigger is better". Typically, people underestimate how much they have. A 15 yard dumpster would be the smallest recommended. If couches or mattresses are involved, 20 yards is highly recommended.

If this is for construction or remodeling debris, weight is a bigger issue than volume. 10 yards is fine for a typical bathroom or a smaller kitchen. 10 yards is the only dumpster we have available for roofing(it will hold about 22 square of shingles). The 15 yard is great for an average kitchen. If you arent replacing cabinets, 10 is ok. 20 yard dumpsters are not recommended unless the debris is lightweight(think carpets, insulation, wood, vinyl siding. definitely not concrete and only small amounts of sheetrock).