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Making a Roman Blind part 1 – How to calculate material & lining

Roman Blinds make smart window furnishings and are not too difficult to make.  There are some good you tube tutorials to help you and we also run courses here in the shop for those living close enough to attend.


One of the things that people find confusing when considering a roman blind is how to calculate how much fabric they will need as well as the amount of lining and the quantities of the other components used the hang the blind.  Firstly, decide if the blind is going to hang outside of the window or in the recess and then measure the width and the drop. If hanging outside the recess it is usual to take the blind at least 5cm/2″ outside the recess at each side and above the window.

Calculating Fabric

First calculate the width of fabric needed for your blind by adding 20cm (8″) to the finished width of the blind. Compare this total fabric width needed to your fabric width. The amount for turnings can be reduced slightly, but if your fabric is too narrow then you will need to buy two widths and join the fabrics together.  This is normally done by cutting one width in half and then joining each half to the outside edges of the other width at the selvedges. This way you have a central panel and a strip at each edge.

Add 20cm (8″) to the drop measurement for hems and headings and this will give you the total fabric length needed for one drop for a plain fabric. If the cloth has a pattern repeat and you are making more than one blind, or you are making a blind with more than one width of fabric you will need a little extra material in order to make sure all the drops or blinds start at the same place on the pattern (so that they match). To work this out, firstly measure the pattern repeat.  Divide the total drop measurement, including the 20cm for hems, by the pattern repeat and round UP to the next whole number. This will tell you how many pattern repeats you will need for each drop (or blind).  Times that number, by the pattern repeat measurement (eg. 5x42cm) and this will give you the total amount of fabric for one drop. Multiply by the number of drops needed for your blind or blinds to get the total fabric requirement.

Calculating Lining

There are two ways to create the channels in the lining in order to create the pleats of the roman blind.  The easiest way to calculate the number of channels is to draw out a rectangle similar to your window and write on the side the required finished drop measurement. Draw one line 6″ (15cm) from the bottom and one line 4″ (10cm) from the top.  Take this total (10″ (25cm)) from the finished drop measurement and divide the remainder by 12 (30 if you are working in cm) and round it up.  This is the number of spaces between your rods (channels)so +1 to find the total number of rods (channels) needed.     Then follow A or B below.

A :              If you are using fiberglass rods and Roman Blind tape you can mark these measurements on the lining with tailors chalk  ready to sew the tape straight on top.   You can calculate the number of drops of lining in the same way as for the fabric above. Add 8″ (20cm) for your hems and headings on to your drop measurement and this will be the total amount of lining, then multiply this by the number of drops of lining to get the total amount you will need.

B:              If you wish to sew in your own channels and use wooden dowel, add 2″ (5cm) for each channel, x by the number of channels and add this to the finished drop.  Calculate number of drops as above, then add  8″ (20cm) for your hems and headings on to your drop measurement (including the extra for the channels). Multiply by the number of drops and this will be the total amount of lining you will need.

Look out for part 2 where we will show you how to calculate the other components for your Roman Blind. We are also happy to carry out the calculations for you if you are purchasing our fabric.

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