How to convert a knitting pattern to your size 

You have found a great knitting pattern for a jumper but it doesn’t come in your size – what do you do?

I get quite a few enquiries for help with adjusting knitting patterns, so I thought you may find these instructions useful. It is possible to convert most patterns so that they suit your requirements.

Here are the most important steps:

Step 1: Make a tension square

Before you do anything else, you need to knit up a tension square in the yarn you are planning to use and in the stitch pattern you are going to do. So, if your knitting pattern is for a jumper in stocking stitch, make your tension square in stocking stitch. If your pattern includes cables or lace stitches, you need to have a tension square with cables or lace stitches.

Count the number of stitches over 10cm and the number of rows over 10cm. This is your tension.

You should work a tension square every time, even if you are planning to knit according to the pattern and with the recommended yarn. Every knitter has a different tension, and you will only achieve the right size if your tension matches that in the pattern.

Step 2: Work out your personal measurements

To achieve a perfect fit, measure a jumper that fits you well so you know which size you are aiming for. Just remember that the thicker the yarn, the bigger the jumper needs to be, so choose something that is comparable to the sweater you are planning to make.

Step 3: Compare measurements

Compare the size of your jumper with the measurements in the pattern. Some patterns include a cut diagram, which is very helpful to work out by how much you need to increase or decrease the pattern. Ideally, you want to produce a 1:1 cut diagram (this is the same idea as a sewing pattern) for the size you need to achieve. This is also very useful to measure your progress against while you are knitting.

Step 4: Calculate required number of stitches

Use the rule of proportion to work out how many stitches and how many rows you need to achieve the width and length you want. 

Let’s have a look at a concrete example of how to convert a pattern:

Let's assume you have taken measurements of your favourite jumper. In this example, you have worked out that your jumper needs to measure 55cm across and should have a total length of 64cm. You want to work 2cm of ribbing and start the armhole at 40cm from the ribbing. Your neckline measures 18cm across. The shoulders have a width of 9.5cm each and a drop of approximately 1cm.

Your sleeves should have a total length of 57cm including ribbing and should measure 38cm at their widest part and 24cm cuff width.

This is what your diagram should approximately look like:

Next, you need to work out how to change the size of your pattern. This is done by using the rule of proportion.

Let’s take your tension square measures 16 stitches and 24 rows for a 10cm x10cm square. That means that you need to work 16 stitches for every 10cm. Let’s say you want to make a jumper that is 55cm wide. First, work out how many stitches you need per 1cm.

This requires a little bit of maths. Alternatively, you can use a converter tool such as the Prym Knitting Gauge Converter Tool. 

To work out the number of rows, you do the same for the length of the garment:

Armholes: Use the original pattern instructions to help you guide how many stitches you should bind off for the armholes - these instructions usually do not change that much across different sizes. Alternatively, you can also use your cut diagram as reference.

Neckline: Use the same method to work out how many stitches you need to achieve the size of your neckline: 

Shoulders: Use your original pattern instructions for guidance on how to decrease for the shoulders.

Sleeves: Work out the number of stitches to cast on based on the method above. 

To shape the sleeves, you need to work out how many stitches you need to increase over the length of your sleeve up to the armhole to achieve the desired width. In our example, you start off with 24cm width and need to increase to 38cm. These increases occur evenly over 41cm length (96 rows).

That means increase 1 stitch both sides every 8^th row eleven times to achieve the desired increases.

To shape the top of the sleeve, use the original patterns – there is usually not a huge difference when working the sleeve caps. Alternatively, use your cut diagram as a guidance to shape the sleeve caps.

How to work out repeat patterns

If you are working a repeating pattern, you need to take that into account and adapt either your sizing or the pattern.

For example, you have a lace pattern that involves a sequence of, say, 10 stitches. This 10-stitch pattern then gets repeated over the width of your garment. Let's assume you are working 86 stitches across the width of your garment, which means that you get 8 full pattern sequences and then you are left with 6 stitches.

You now have two options: you can either adapt the pattern so that at the beginning and end of each row you work 3 knit stitches or a partial pattern, or you can increase or decrease the overall width to allow for repeating the full pattern multiple times across your sweater.

Have a look at the original pattern instructions and check how it deals with different sizes – this will give you a good idea on how to best solve this issue.