Gravel calculator

Bulk density is a measured property, not a constant. The standard test fills a container of known volume with loose material and weighs it — air gaps included, because the air gaps are part of what you are buying and hauling. The result moves with three things.

The rock itself. Granite, limestone and river stone have genuinely different specific gravities. The gradation. A well-graded material with fines packs tighter than a single-size stone, because the small particles fill the spaces between the large ones. And moisture, which dominates everything else.

A cubic yard of sand can swing four hundred pounds between a dry pile and one that has sat through a wet week. If the yard sells by weight, rain is something you pay for. That is not a quirk to work around — it is the single most useful thing to know before you order, and it is why ordering after a dry spell is a real saving rather than folklore.

Every other calculator in this market hands you one tonnage. It is not that their arithmetic is wrong — it is that the input was never a single number, so the output cannot honestly be one either. Publishing both ends is the whole reason this page exists.

The commonest way to come up short on an aggregate order is also the most reasonable looking: work out the finished layer, and order exactly that. Material arrives loose. Once it is raked out and rolled, it occupies noticeably less space than it did in the pile.

How much less depends on the fines. Crusher run keeps its stone dust, and under a plate compactor that dust migrates into the voids between the larger pieces — so it loses about a fifth of its loose volume, and gains the load-bearing behaviour that makes it a base. Clean washed stone has no fines to move, so it barely compacts at all: it settles a few per cent and locks together mechanically.

It is also why the waste allowance here is smaller than you may have seen elsewhere. On this page, waste means waste: the edge that never finishes square, what stays in the barrow, the ruts that swallow stone on ground nobody graded. The settling is a separate, named, per-material figure rather than something hidden inside a round number.

That change is recorded. The aggregate allowance used to be a flat ten per cent that was really the settling in disguise, and keeping both would have counted the same thing twice and over-ordered every job. It is in the data changelog, which is what that page is for.

Crusher run and #57 stone look almost identical in a photograph and behave like different materials. Nearly every failed patio and silted-up drain in a residential yard comes down to the two being swapped.

The rule is short: base rock under things, clean stone where water has to get away. Using clean stone as a base is why a patio settles into waves. Using a material with fines in a drain is why the drain silts up and stops working in its third winter.

Pea gravel and river rock are a third category — decorative, rounded, and incapable of interlocking. They are comfortable to walk on and terrible under anything with wheels, and without an edge restraint they will be on the lawn within a season. The calculator says so when you pick one.

Depth is where a job is won or lost, and it is the figure people guess at most. These are the defaults the calculator applies, and the reason behind each.

Aggregate is the cheapest material on this site and one of the most expensive to move. The stone is worth tens of dollars a ton; the truck that brings it is worth the same whether it arrives with one ton or fifteen. That single fact decides most small jobs.

Yards charge a flat haul fee per load — roughly $60 to $125 — and set a minimum order of about 1 ton. Spread across a full load that fee disappears into the price. Spread across one ton, it can double what you pay.

This is the counter-intuitive bit: bagged gravel from a big-box store costs several times more per ton than bulk, and below about half a cubic yard it is still the cheaper way to buy — because you are not paying for a truck. The calculator switches its recommendation at that crossover, and tells you why rather than just doing it.

One practical consequence: if you have two small jobs a month apart, do them in the same week. One delivery of three tons costs far less than two deliveries of a ton and a half.

“I’ll just collect it” is the plan that most often meets physics. A cubic yard of stone weighs over a ton and a half. A half-ton pickup has roughly 1000 lb of payload — about a third of a yard — and a three-quarter ton around 2000 lb.

Payload includes you, your passengers and anything already in the bed. Overloading is not a matter of whether the springs cope on the way home; it is brakes, steering and, if it goes wrong, insurance. Yards will happily load whatever you ask for and the responsibility is yours at the gate.

The result panel prints the number of loads for exactly this reason. Four trips across town, with loading and unloading at both ends, is most of a Saturday — and the delivery you were avoiding costs less than the fuel and considerably less than the springs.

Every figure it uses is published. The weights come from a survey of quarry and landscape supplier data, expressed as the range they span; the depths and compaction allowances from residential practice and the base guidance paver manufacturers publish for their own products; the prices from delivered residential pricing. All of it is listed, dated and linked on the sources page, and the underlying tables are free to take from the aggregate weights table.

Nothing you type is sent anywhere. The whole calculation runs in your browser, ZIP code included — that only selects a regional labour factor, and is never transmitted.

Half the difficulty of ordering aggregate is that the trade has three names for everything. These are the ones worth knowing before you phone.