How dumpster sizes are measured
Roll-off sizes are stated in cubic yards, which is a measure of volume, not weight. A 20 yard container holds twenty cubic yards of loose debris when it is filled level with the top rail. That number tells you nothing about how heavy the load is allowed to be, which is why the two questions have to be answered together.
For a rough sense of scale, one cubic yard is about the volume of a standard washing machine, and a full-size pickup bed holds roughly two to three cubic yards of loose material. Bagged household junk compresses; framing lumber and furniture do not, so the same "amount of stuff" can occupy very different volumes depending on shape.
Volume versus weight
Dense debris is the usual reason a job needs a smaller container than the owner expects. Concrete, brick, dirt, tile, plaster and asphalt shingles all reach a hauling weight limit long before they fill a large box. Loading heavy material into a 30 yard container almost always ends with a container that cannot be legally transported. If your project generates any of that material, tell us before delivery — it changes the recommendation.
Light, bulky debris runs the opposite direction. Furniture, cardboard, insulation, deck boards and general household junk fill volume fast without adding much weight, which is exactly what the larger containers are built for.
Which size for which project
Still unsure?
Work through the what size dumpster do I need guide, which walks through common project types and the questions we ask on the phone. You can also read how dumpster rental pricing works, since size and debris type are the two biggest inputs, or call (518) 742-7908 and describe the job.