It is my guess that the valance is 1.5 - 2.0 times the width of the window. Fuller curtains are usually 2-3 times the width of your window. As for tab placement I just distribute them evenly across the width of your valance (width of valance, minus total width of your tabs and valance edge, divided by number of spaces between tabs).
If your window is 30 inches your valance is 60 inches (2X for ease of calculation) minus 6 tabs @ 2" finished (60-12=48) minus 1.5" edge on each end (48-3=45) divided by 5 spaces (45/5+=9) 9" spacing between your finished tabs
You will need to add for any seaming and hemming that is needed. These are all just approx. numbers but hopefully you get the idea.
Hope this is helpful.
Last edited by MamaBear61; 04-30-2013 at 01:11 PM.
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