Take the sizes of the window recess and add on an overlap – we recommend 150 mm at each side and the top.

The drop can be as desired, but ensuring clearance from the floor or a radiator etc., for example a 15 mm floor clearance. For ceiling fix brackets the curtain height may need exact adjustment.

The wave curtain width should be calculated in wave multiples from the curtain width measured in the previous step. There are always an odd number of wave folds in each curtain to turn in to the wall at the ends – 5 in the example here.

The measured size is rounded up to the next full 160 mm wave pitch for each curtain to ensure correct function and appearance. So, for a two way draw curtain this size step is 320 mm.

Calculating the curtain width

Curtain width increments for reference

Calculating the pole width

Because we’ve rounded up the curtain width to match the waves exactly, it’s likely that a pole to match will be over the required length when fitted. So, take the original measurement of curtain width from the wall and base the pole on this size – the curtain will stay at the wave multiple width and concertina down. If the curtain runs on a pole reduced in width it will look like this before and after example:

Two way draw – calculated by wave size

Two way draw – reduced size example

Calculation of pole sizing

Take the reduced size total curtain width - the original measurement from the wall - and add twice the pole projection beyond the end of the curtain to get the cut length of the aluminium pole itself – this is plus 59 x 2 mm.

The pole has a pulley housing at each end that will add another 31 x 2 mm – shown by dotted lines in the diagram.

Finally, add the net finial length twice to get the overall size of the finished pole. Because of the finial mounting collar, this is the length of the finial less the depth of the collar.