Standard sheet sizes for metal are usually as follows:
1 x 2, 1.25 x 2.5, 1.5 x 3, 2 x 4, 3 x 6 (in metres)
However if you want a profile that is fractionally longer than a standard sheet size, it may cost you significantly more, as it will probably require the use of the next largest sheet size, potentially wasting a lot of it.
We also usually allow 20mm all round the edge of the sheet to allow for setting up and is therefore ignored in the sheet yield.
Visit the Hydromar Ltd website for more information on Sheet sizes