Pattern matching can be a little tricky and it took me quite a while to get my head around it.
Here is a little guide on what technique works well for me, I’m sure that there are easier ways to do it but this works out ok for me.
Remember that when you are pattern matching, you will need more fabric than the pattern describes as you will need to find where the pattern repeats.
The example below shows you the method for sewing a back bodice with a centre back seam e.g. where a zip will be inserted.
Laying out the fabric
When pattern matching is required do not fold the fabric in half to cut out your pattern pieces (as you would normally) instead lay your fabric unfolded, with the right side facing up.
Then mark with a tailors chalk where you want the centre seam to run as shown in the picture below.
Cutting out the first pattern piece
As you are not working with the fabric folded in half, you will need to cut out each pattern piece individually.
We will first of all cut the left hand side, notice how the paper pattern is right side facing up.
Measure 1.5cm (or whatever your seam allowance is) to the RIGHT of the centre line that you have just drawn.
Now place the pattern piece so that the centre back of the pattern piece overlaps the centre line that you have drawn by 1.5cm all the way down, as shown in the 2 pictures below.
Pin and cut out.
Then, temporarily fold the centre back seam along where the seam line will be (use the chalk line as a guide) e.g fold it in 1.5cm to the wrong side, and put a few pins in to keep it in place (this just helps to identify where you need to match the pattern.
cut out the second pattern piece
This time we are going to cut out the right hand side pattern piece, ensure that you have flipped your paper pattern so that the wrong side of the paper pattern is facing you, otherwise you will end up with 2 left hand pieces.
Find the point where the pattern repeats the pattern on the left hand side that you have cut out as shown below.
Place the left hand fabric piece on top of the fabric (where you have found that it matches) and use the chalk to mark the centre fold line (I use a ruler and place that on top of the left hand fabric piece with the edge of the ruler lining up with the folded edge of the fabric.
Also mark the top and bottom of the left hand fabric piece, this just makes it easier to keep the pattern symmetrical.
Ensure that you have the paper pattern flipped so that the wrong side of the pattern is facing you.
Mark 1.5cm to the LEFT hand side of the centre fold line and place the paper pattern overlapping the centre fold line by 1.5cm all the way down, also lining the top and bottom of the pattern to the marks that you made.
Pin and cut out.
Remove the fabric from the paper pattern and temporarily fold the centre back seam allowance in (as you did on the left hand side)
Check it all matches
Now, lets check that it all matches up.
Place the left and right hand fabric pieces, with the right side of the fabric facing you, and the centre back lines matching in the centre.
Tah Dah! You have pattern matched.
Open out the seam allowance again and attach your zip in the normal way, you will end up with the pattern matched as above.
I hope that helps!!