Plate 13 of 13Grading and choosing
Reading a Delivery Ticket and Measuring Volume
What the weights on a weighbridge ticket mean, how tonnes, tons and cubic yards relate, and how to turn a length, width and depth into a volume of stone.
A first delivery of sand, gravel or crushed stone usually comes with a printed slip full of numbers. This page explains what the weights on a weighbridge ticket generally mean, how the units (tonne, short ton, cubic yard and cubic metre) relate, how to turn an area and a depth into a volume, and why converting between weight and volume only ever gives a range. It is generic and educational. It describes public-works practice from the sources cited, which is not the same as every commercial ticket, and it names no supplier.
What a weighbridge ticket typically shows
The Iowa Department of Transportation's construction manual describes the weight ticket used for materials bought by weight. It says aggregates are generally weighed in the delivery vehicle on a platform scale, and that the ticket for each load shows the required weight information, the project number or contract description, the truck number, the date and the type of material. For truck platform scales, tickets printed automatically include the gross weight, the tare weight of the truck and the net weight of the load. For manual weighing, a weighmaster includes the gross and tare weights and calculates the net weight on the ticket.
Those three weights are the heart of the slip. Gross weight is the loaded truck. Tare weight is the empty truck, and net weight is the difference, which is the material actually delivered. The Iowa manual requires each truck to be tared daily, and the Michigan Department of Transportation's construction manual says tare weights should be recorded at least twice a day, once in the morning and once in the afternoon, with aggregates weighed to the nearest 100 pounds. A ticket may carry more or fewer fields than these, since the sources describe highway contracts, and a smaller commercial ticket may be simpler. The list in Iowa's manual is the one this page relies on.
Michigan's manual shows one reason the material description matters. When aggregate base is paid for by weight and the moisture content exceeds 8 percent, the load ticket is reduced to remove the excess moisture. That is a rule for state road contracts. It shows that a ticket weight includes the water held in the stone, which is why wet material weighs more. In Iowa's case, platform scales used for measuring pay quantities must meet the requirements of the Iowa Department of Agriculture.
Units: tonne, short ton, cubic yard and cubic metre
Words for weight vary between countries. The National Institute of Standards and Technology's Handbook 44 explains that an unmodified "ton" is commonly understood to mean the 2,000-pound ton, which may be called net or short to distinguish it from gross (long) tons. It lists 1 net or short ton as exactly 2,000 pounds, or 0.907 metric ton, and the metric ton (tonne) as 1,000 kilograms, or about 2,204.6 pounds. A metric tonne therefore weighs about 10 percent more than a US short ton. Because the words overlap, read the ticket to see which unit is meant.
Volume units have the same pitfalls. The same NIST table gives 1 cubic yard as exactly 27 cubic feet and about 0.765 cubic metre, so 1 cubic metre is about 1.308 cubic yards. Bulk materials are often sold by weight, by volume or both, and Michigan's manual notes that aggregate base can be paid by weight, area, volume or per each area completed. Check which unit applies to the price and which to the delivery.
Measuring an area to volume
The volume of a rectangular layer is its length multiplied by its width multiplied by its depth, with all three in the same unit. The usual error is mixing units, such as feet for the area and inches for the depth. Convert inches to feet by dividing by 12, or centimetres to metres by dividing by 100. Volume in cubic feet divides by 27 to give cubic yards, and a layer measured in metres already gives cubic metres.
As an illustration, a bed 20 feet long, 10 feet wide and 4 inches deep has an area of 200 square feet. At 4 inches, or one third of a foot, that gives about 66.7 cubic feet, which is 2.47 cubic yards. In metric terms, a bed 6 m by 3 m and 10 cm deep is 6 × 3 × 0.10, or 1.8 cubic metres. Michigan's manual follows the same logic: when aggregate is measured by area, length and width for a given thickness give square yards, and when it is measured by volume, plan dimensions give cubic yards, with "loose measure" counted by the hauling units.
Loose volume and compacted volume differ. The Federal Highway Administration's gravel-roads guide says material in a stockpile or truck is very loose with very low density, and that in many parts of the country ordinary compaction reduces the volume of a new gravel layer by 30 percent or more. It recommends allowing for that shrinkage when working out how much depth will remain after compaction. A calculation that ignores shrinkage will leave the finished layer thinner than planned.
Tonnes versus cubic yards: a range, not a constant
Turning volume into weight needs a density, and density changes with the kind of stone, how tightly it is packed and how wet it is. A material weight chart on the TRORC website, which says its weights were gathered from the EPA and NTEA, lists pounds per cubic yard. The table below shows a few rows, with columns for short tons and kilograms per cubic metre calculated here from the chart's pounds using NIST's conversion factors.
| Material (chart wording) | Pounds per cubic yard | Short tons per cubic yard | Kilograms per cubic metre |
|---|---|---|---|
| Crushed stone | 2,700 | 1.35 | 1,602 |
| Gravel, dry, 3/4 | 2,565 | 1.28 | 1,522 |
| Gravel, wet, 3/4 | 3,375 | 1.69 | 2,002 |
| Sand, dry | 2,750 | 1.38 | 1,632 |
| Sand, wet | 3,300 | 1.65 | 1,958 |
The dry and wet gravel rows show the effect of water directly, since the wet figure is about 32 percent higher. Using the example bed of 2.47 cubic yards, dry gravel would weigh about 3.2 short tons and wet gravel about 4.2. The 1.8 cubic metre bed would weigh roughly 2.7 to 3.6 tonnes over the same range. Those are illustrations and not ordering advice, and they leave out compaction shrinkage. Another stone type, another size grading or another moisture level will move the numbers. The chart is a general planning reference from one source, and published values from other sources will differ, so the weighed net figure on the ticket is the record of what was delivered.
Different grading changes density too, since a well-graded material packs more mass into the same space than a uniform one, as explained in aggregate sizes, grading and choosing material. If the load is for a base layer, crushed stone bases covers how the stone is placed and compacted, and gravel for driveways and drainage covers surface and drainage uses. For other materials sold by the load, sand types and uses is a good companion.
Rules about scales, tickets and units differ by country and by site. The local weights-and-measures authority is the reference for trade rules where you live, and the seller's ticket remains the official record of that delivery.
Frequently asked questions
What is the difference between gross, tare and net weight?
Gross is the loaded vehicle, tare is the empty vehicle, and net is the load alone. Iowa's manual says platform-scale tickets show all three, and that a weighmaster who weighs by hand calculates the net on the ticket.
Is a ton the same as a tonne?
No. NIST lists the short ton at exactly 2,000 pounds, or 0.907 metric ton, while the metric tonne is 1,000 kilograms. The difference is roughly 10 percent, which matters for large orders.
Why does wet stone weigh more?
Water held between and within the particles adds weight without adding volume. The TRORC chart gives 3/4 gravel at 2,565 pounds per cubic yard dry and 3,375 wet, and Michigan's manual adjusts load tickets when moisture exceeds 8 percent on its weight-paid base contracts.
Why is less stone left after spreading than I ordered?
Loose stone in a truck has low density, and compaction squeezes out voids. The FHWA gravel-roads guide says shrinkage of 30 percent or more in volume is common after ordinary compaction in many parts of the country.
The short version
A weighbridge ticket records gross, tare and net weight along with the date and a description of the material, and the net figure is what was delivered. Convert area and depth to volume with consistent units, allow for compaction, and treat any weight-to-volume conversion as a range because density changes with stone type and moisture. Local rules and the seller's ticket govern the actual transaction.