What about Valances and Pelmets
Measuring for Valances Measure the length of the valance track and returns and multiply by the same formula as used above for working curtain fabric out and the number of widths, you will also need to take into consideration on patterned fabrics how the pattern is going to sit on the valance.
Measuring for Pelmets
Measure the length of the pelmet board, including returns, if more than one width of fabric is required do not put a seam in the middle, so if two widths are to be used but one width in half and join both sides of the other width and centralise to the middle of the board. Rember again with pattern fabric the positioning of the pattern on the pelmet.