What size dumpster do I need?
Two questions, not one: will it fit, and what will it weigh. Most size guides only answer the first. You get billed on the second.
Work out your size
The short version, before the arithmetic: a full box of household clear-out is roughly 1.6 to 4.4 tons, against an included allowance that is commonly 2 to 5. The lightest thing you can put in a dumpster is already brushing the allowance. That is the surprise on most invoices — not concrete.
For concrete, brick, dirt, gravel or tile, the answer is not a size at all. Those go in a dedicated clean-fill container, and a general box full of them cannot legally leave your driveway.
For a small load under about two and a half cubic yards — a garage corner, one room cleared — a dumpster bag is usually the easier answer than a truck in the driveway for a week.
Why the two failures aren't the same
Overfill a dumpster and the driver won't tow it. Not "won't tow it today" — won't tow it until you climb in and redistribute the load by hand, with the truck waiting. The project stops.
Go over the weight allowance and you get a line on the invoice. Annoying, sometimes expensive, but you find out afterwards and the job keeps moving.
Those two outcomes are not equally bad, so this tool won't treat them as though they are. It leaves room in the box rather than filling it to the brim, and it tells you what the load is likely to weigh instead of staying quiet and letting the invoice explain it later.
Why a hauler might send you a smaller box
It sounds like a mistake and it isn't. A cubic yard of household clear-out is light. A cubic yard of concrete, brick, dirt or roofing shingles is heavy enough that a large box full of it can exceed what the truck is allowed to carry on the road. For those materials the answer really is a smaller container and more pickups.
Same volume, completely different weight. That is the thing this site is being built to compute.
The truck, not the box, is the real limit
A roll-off truck may legally haul something like 8 to 12 tons, and that does not scale with the container. A 40-yard box has the same truck under it as a 10-yard. So for dense material you are not renting volume, you are renting weight — and the honest answer is a line to stop filling at, not a bigger box.
Plenty of haulers will tell you to rent smaller for heavy debris. What almost nobody explains is why, and the why is the whole thing: one truck, one limit, every size.
What we can't tell you
Confirm the weight allowance and the banned-material list with your hauler before you book. Both are set locally — the allowance disagrees by two to three times between companies, and it is the number you are billed against. Every figure here is national and typical. Where we don't know, we say so rather than guessing.