The box has two capacities and they do not expire together
A 30 yard box loaded to 90 percent is 27 usable cubic yards. At 900 lb a cubic yard that is 24,300 lb of material. But the hauler contract on the defaults allows 20,000 lb before overage, so the box is full at 20,000 and there are 4.8 cubic yards of it still empty when that happens.
At 6,000 lb an operating day, 20,000 lb takes 3.33 days. That is the number everything else comes from: 22 operating days divided by 3.33 is 6.6 pulls a month, and 6.6 pulls at 285 dollars each is 1,881 dollars against 66 short tons, or 28.50 a ton.
Had the allowance been higher, the yardage would have bound instead at 24,300 lb, the box would have lasted 4.05 days, and the same month would have taken 5.4 pulls instead of 6.6. Same yard, same material, 1,548.15 in pull charges instead of 1,881.00 — 18 percent less, decided entirely by which of the two limits arrives first.
The call day is not the full day
With a one day lead time, a box that fills in 3.33 days has to be called at day 2.33, when it holds 14,000 lb and has 6,000 lb of room left. That is exactly one normal day of margin. A delivery twice the usual size on day two, or a hauler running one day behind their average, and the box is full before the truck arrives.
The page prints the call day as a percentage of the fill when it gets tight, because that ratio is the real measure of how much slack a yard has. Below about a quarter it is not slack, it is luck.
A late swap often costs nothing and costs a lot
Two days late on the defaults is 12,000 lb with nowhere to go — 13.3 cubic yards, which stacked four feet high is 90 square feet of floor. The invoice, meanwhile, does not move at all: the box has been held 5.33 days against seven included in the pull, so no rental day is billed and the delay is free according to the paperwork.
That is why late swaps get tolerated for months at a time. The cost is real and it is entirely in floor and handling, and neither of those ever appears on a bill. Material stacked on the ground gets moved twice, and the second move is by hand or by machine at exactly the moment the yard is busiest.
What the average hides
Everything here runs on one number, the pounds a day, and the number is an average of something that is not average. A yard taking 6,000 lb a day takes 1,500 one day and 15,000 the next, and it is the second day that decides whether there is metal on the ground. Use the fill days as the middle of a range rather than as a schedule, and set the call day earlier than the arithmetic says by about the size of a bad day. The alternative is a second box, and the comparison worth running is its standing charge against how often you actually overflow.
Questions people ask
How do I know how fast a scrap container fills?
Weigh what goes in it for a fortnight and divide by the days. Everything else is guessing at a density, and loose density in a box is the number people are most wrong about — long light material can sit at a quarter of what an estimate assumes. On the defaults, 6,000 lb a day into a box that binds at 20,000 lb is 3.33 operating days.
Should I get a bigger container?
Only if the yardage is what runs out. When the weight allowance binds first, a bigger box just gives you more empty space above the same 20,000 lb and the pulls do not get any further apart. The page names which limit you are hitting for exactly this reason, because it is the one question a size change actually answers.
When should I call for the swap?
The fill days less the lead time. On the defaults that is day 2.33 of a 3.33 day fill, when the box holds 14,000 lb. If that gap is under about a quarter of the fill, there is no margin left for a heavy day and a second box on site is usually the cheaper answer to a problem that is otherwise going to keep happening.
What does a late swap actually cost?
Usually nothing on the invoice and a lot on the floor. Two days late at 6,000 lb a day is 12,000 lb, 13.3 cubic yards, about 90 square feet stacked four feet high, and it all gets handled twice. Meanwhile the box has been held 5.33 days against seven included, so the bill shows no change at all. That mismatch is why the problem persists.
How do I get from pull charges to a cost per ton?
Multiply the pulls a month by what a pull costs including any rental days billed, then divide by the tons that actually moved. On the defaults that is 6.6 pulls at 285 dollars against 66 tons, which is 28.50 a short ton. It is the only form of the number that can be compared against a price per ton from anywhere else.