A sheet weighs its area times its grammage: a 1.22 by 2.44 meter sheet in 4 mm at 600 g/m² weighs about 1.8 kilos. Multiply by the sheets in the order and add the bases and packing materials.
Why gauge alone does not tell you how much your order weighs
In purchasing, sheet is ordered by gauge and by number of sheets. For freight, those two figures fall short. Weight depends on how much polypropylene each square meter carries, and that figure has its own name: grammage. If you quote transport by gauge alone, the error can exceed half of the actual weight.
Grammage is the figure that carries the weight
Grammage is expressed in grams per square meter (g/m²) and equals the weight of a piece of sheet one meter on each side. Polypropylene has a density close to 0.9 grams per cubic centimeter, so a solid 1 mm plate would weigh about 900 g/m². Corrugated sheet spreads a similar amount of material, or less, across two thin faces joined by ribs. That is why a 4 mm sheet at 600 g/m² weighs less than that solid 1 mm plate.
Two 4 mm sheets with very different weights
Each gauge is made within a range of grammages. In our production table, 4 mm sheet runs from 600 to 1,000 g/m². A 1.22 by 2.44 meter sheet in 4 mm at 600 g/m² weighs about 1.8 kilos. The same sheet at 1,000 g/m² weighs close to 3 kilos. With the same gauge and the same size, the second one weighs two thirds more. A pallet of 275 sheets goes from about 490 kilos to about 820.
The number of sheets changes the weight more than the number of pallets
Our standard combinations ship on pallets with a fixed number of sheets: 500 in 2 mm, 330 in 3 mm, 275 in 4 mm, 200 in 5 mm and 160 in 6 mm. All of them form a stack of about one meter, which is why the pallets weigh about the same, between 490 and 620 kilos of sheet. The problem appears when the order is counted in sheets. A thousand 2 mm sheets fit on two pallets; a thousand 6 mm sheets take up seven. Weight and truck space triple with the same number of sheets, just as the buyer in the opening found out.
How to calculate your order weight in four steps
The calculation fits in a spreadsheet and works for any order, whether it is standard sheets or custom-cut parts. You need three figures from your purchase order: size, grammage and quantity.
Step 1: calculate the area of the sheet or the part
Multiply length by width in meters. The standard sheet, 1.22 by 2.44 meters, measures 2.98 square meters. If you buy cut parts, use the size of the part. A 60 by 40 centimeter divider measures 0.24 square meters. If the part has large die cuts or windows, subtract their area so you avoid inflating the weight.
Step 2: multiply by grammage and convert to kilos
Multiply the area by the grammage and divide by a thousand to get kilos. These are the reference weights per standard 1.22 by 2.44 meter sheet with our gauge and grammage combinations:
- 2 mm at 400 g/m²: about 1.2 kilos per sheet.
- 3 mm at 550 g/m²: about 1.6 kilos per sheet.
- 4 mm at 600, 650 or 700 g/m²: between 1.8 and 2.1 kilos per sheet.
- 5 mm at 1,000 g/m²: about 3 kilos per sheet.
- 6 mm at 1,300 g/m²: about 3.9 kilos per sheet.
For the 0.24 square meter divider in 4 mm at 650 g/m², the result is 156 grams per part.
Step 3: multiply by the order quantity
Multiply the weight per sheet or per part by the quantity you will receive. A thousand 6 mm sheets at 1,300 g/m² add up to about 3,870 kilos of sheet. Four thousand 156 gram dividers add up to 624 kilos. When you buy cut parts, the weight that travels is the weight of the parts, because the cutting scrap stays at our plant.
Step 4: add the bases, the packing and the grammage tolerance
To the sheet weight, add the weight of each base, the corner boards, the strapping and the film that wraps the pallet. Ask for those weights in the quote, because the base for sheet must be at least as large as the sheet and weighs more than a common pallet. Also factor in the grammage tolerance listed on the data sheet. To reserve truck capacity, calculate with the upper limit of that tolerance.
What a miscalculated weight costs you in freight
A poorly estimated weight gets paid for in three places: in the truck you booked, in the parcel carrier's rate and in the equipment that receives the material at your dock.
Wasted trips and rescheduling
If the truck arrives and the order exceeds its weight or floor capacity, the carrier charges for the trip even without loading. Then another truck has to be found, and the delivery date moves. Stacking sheet pallets on top of each other during the trip is also a bad idea: the weight of one pallet marks the top sheets of the pallet below. Each pallet takes its own spot on the trailer floor, and that space also goes into the quote.
Actual weight versus dimensional weight in parcel shipping
Parcel carriers charge the greater of the actual weight and the dimensional weight. Dimensional weight is obtained by multiplying length, width and height in centimeters and dividing by a factor each company publishes; a common factor is 5,000. Sheet is light for the space it takes up. A package of 50 parts measuring one meter by half a meter, in 4 mm at 600 g/m², weighs 15 kilos and measures 100 by 50 by 20 centimeters. Its dimensional weight is 20 kilos, and those 20 kilos are what you pay for.
The capacity of your forklift, your rack and your dock
The order weight also determines how you receive it. A 6 mm pallet comes to around 620 kilos of sheet plus its base, and the thousand sheets from the opening approach four tons with their bases. Check your forklift capacity, the load allowed per rack level and the floor space you need before the delivery date.
How to check the actual weight when the sheet arrives
The calculation helps you quote. The scale confirms that you received what you ordered. Two simple tests let you verify the grammage of the sheet and the weight of the shipment.
Weigh a full sheet and divide by its area
Weigh a standard sheet in grams and divide the result by 2.98. The number you get is the average grammage of the whole sheet. A 4 mm sheet at 600 g/m² should weigh about 1.8 kilos; a 6 mm sheet at 1,300 g/m², about 3.9. If the result falls outside the tolerance range on the data sheet, repeat with other sheets from the same pallet before reporting it.
Weigh a pallet and compare it with the packing slip
If your dock has a floor scale, weigh a full pallet and subtract the weight of the base and the packing. Compare the result with the number of sheets times their calculated weight. A large difference points to a grammage different from your purchase order or a sheet count that does not match, and both are worth clearing up before you open the pallet for production.
Before you quote your next freight, convert your order from sheets to kilos with the grammage on your purchase order. At Cassium we give you the weight per sheet, per pallet and per shipment from the quote onward, so you book the right truck on the first trip. Find your starting gauge, grammage and variant with our Recommender.
