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What is a Half Drop Pattern Repeat?

half drop pattern repeat

What is a half drop pattern repeat, and how do I work with it?

If you’re looking at curtain fabric in the shop, you might sometimes notice a fabric labelled as having a half drop repeat, half repeat or half drop pattern.

This means that every other repeat of the pattern across the width is dropped halfway down from the previous one. It’s important if a fabric is labelled in this way, especially if you are making curtains, and here’s why!

If you’re making curtains with a half drop pattern repeat, you’ll need to be more careful if you’re joining widths together. This is because with a half drop repeat, you won’t be able to match the pattern directly across the width, as you would with most fabrics. In this photo you can see that when you put the two edges of the fabric together, the pattern does not match.

half drop pattern repeat 2


Help – what do I do?

if you want to use that gorgeous fabric with a half-drop pattern repeat, then you need to allow for it in the calculations, when you are calculating curtain fabric.

half drop pattern repeat 1


That’s wrong…

If you don’t make an allowance for the half drop repeat, and just work on the set number of pattern repeats for each length of fabric, you will end up with curtains where the pattern does not match when it’s joined, like this. The answer is to allow for enough fabric to move up half a pattern repeat, so that the edges match when joined.

half drop repeat 3


…and that’s right!

When buying fabric with a half drop repeat, you will need to calculate the fabric and then add on one whole pattern repeat to your order (you don’t need an extra pattern repeat for each width). In theory you can add only a half a pattern repeat, but adding a whole pattern repeat gives you some wriggle room when cutting out, and more choice where on the pattern the curtains will start.

So how does that work?

It’s not too difficult! In the example on our calculating fabric for curtains page we needed 7.56 metres of fabric in total, working with a pattern repeat of 7cm. If the pattern was a half drop repeat, we would now add a further 7cm to this total to get 7.63 metres needed in total, rounded up to 7.7 metres. There are also some special rules that really help if you’re cutting out curtains with a half drop repeat; take a look at the how-to below:

Cutting out curtains with a half drop repeat

Time needed: 1 hour and 30 minutes

Time given is an estimate of the extra time needed to make curtains with a half drop repeat. The actual time taken will depend on factors like how big your curtains are, and how much space you have available to work in.
To help you in the process, here’s a detailed how-to on work with a half drop pattern repeat – and stay sane!

  1. Prepare

    You will need to take a bit more care when cutting out your fabric to get the best results. First of all, think about how many many widths of fabric you need for your project, and number them all in sequence. In our example on the curtain calculator we are working with 4 widths of fabric, so we would number them 1 to 4.

  2. Cut out odd numbers

    You then start by cutting all of the odd numbered widths, in this case 1 and 3. [Hint: it may help to measure and mark all the pieces with small pieces of masking tape on the edge, or with tailors chalk, before you cut anything.] We would cut 2 lengths of 27 pattern repeats from our fabric with no gap between them. it might help to number these pieces before you get confused.

  3. Cut off the half drop

    Next, to make it all work perfectly, you need to cut off half a pattern repeat from the fabric before cutting the even numbered pieces. In our example we would cut half of 7cm, which is 3.5cm. This piece will be discarded unless you have another use for it.

  4. Cut out the even numbers

    Now, go right ahead and cut out all your even numbered widths, again with no gap in between. In our example this is two pieces – width numbers 2 and 4. Again, it would be useful to number these pieces, just to make the next part less stressful!

  5. Joining your drops

    Now you’re ready to sew, and as long as you attach odd numbered widths to even numbered widths, you should find the patterns match perfectly from one width to the next. In our example on the curtain calculator we are making a pair of curtains with two widths of fabric in each so we would now sew width number 2 to width 1 and width number 4 to width 3 making two curtains. If you have an odd number of widths you will have to split one width down the length of the curtain before joining (eg for 3 widths split width 2 and join half to width 1 and half to width 3, making sure the patterns match on the seam).

If you are in any doubt about your calculations and are using one of our fabrics, please do ask us – we’re happy to help!

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