This curtain material calculator will work out the amount of material, lining, header tape and spacing for the track mounting brackets and curtain hooks that you will require for the window. Assumptions 1) The window will have two curtains that match in the middle. 2) Only a whole number of drops will be used per window (N.B. Clearly, if there are an odd number of drops, the middle drop will be divided in half. This will ensure that the patterns will match on both curtains)
If you also have the task of mounting the curtain track, you may find that the manufacturers instructions give general guidance on spacing the track mounting brackets but give no specific dimensions for your length of track and number of brackets that they supply. They will almost certainly give no guidance for the spacing of the hooks.
If the track is to be fitted to the wall beyond the window reveal, we would suggest that the track length is approximately 1.2 times the window width. This will allow the curtains to be opened beyond the edges of the window thus obscuring less of the window. This is of course personal preference.
The calculator below should save you some time.
