I hope I got my maths right...

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Note added at 1 hr 55 mins (2005-07-01 12:53:16 GMT)
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MY MISTAKE, sorry. What I found is 1 pound (britisches Pfund) = 0.453 kg, so it is not 100 kg but 0.453 multiplied by 45, which is 20.385 kg.

Cubic foot seems to be the most likely choice, just from the weight, but also because of these:

The 45 lb. density rule:
If the density of the cargo exceeds 45 lbs per cubic foot, every 45 lbs. of cargo weight is equal to one cubic foot. To compute density cube, take the total weight of the shipment and divide by 45. This will give you your chargeable cubic feet. Sample items that generally are subject to the 45 lb. density rule are steel and tile or products that are high in density.

1000 lb. / 45 = 22.22. Chargeable cube would be 23 cubic feet.

http://atwshipping.com/shippingvol.html

Measurement:
Charges are based on density or the total amount of cubic feet. In order to compute cubic feet, you will need to measure the length, width and height (in inches) of each piece to be shipped. One cubic foot is equal to a single piece with the dimensions of 12" x 12" x 12".

http://www.dgxshipping.com/faq.cfm?CFID=690360&CFTOKEN=84831...