To determine the size cubicle curtain needed, first measure from the track to the desired distance above the floor (usually 10 to 15 inches). That is the HEIGHT.
Once you have the height, you need to calculate the desired TOTAL LENGTH. In the image above, we show only three of numerous configurations. The measuring is the same for each one. Get the total length of the TRACK - being sure to include the corners. In the first example the length will be the length of A. In the second example the TOTAL length will be the length of A, plus the length of B, plus the length of the curve. In the third example, the TOTAL length will the length of A, plus the length of B, plus the length of C, plus the length of the curved portion of the track.
Once you have the TOTAL track length, add 10% to it. This is crucial. In other words if the total length of track was 250 inches, then the total length of fabric needed would be 250 inches PLUS 10% (25 inches), for a TOTAL of 275 inches.