Most knitting patterns take the guesswork out of determining how to buy enough yarn for your project. But what if you’re modifying the pattern a little, or even designing a knitting pattern on your own? Even substituting yarn can result in a change in how many skeins you’ll need to buy. Check out these tips for how to buy enough yarn for your knitting project, whether you’re modifying a pattern, substituting yarn, or designing your own pattern.

[box type=”shadow”]Needing to convert yarn lengths and needles sizes into metric measurements? Use our handy metric conversion guide for knitting and crochet.[/box]

Schachenmayr Bravo Big Color Yarn

## 1. If you’re modifying a pattern

Make a list of all the ways you plan to modify the pattern. This is especially important when you’re working with something as customizable as a sweater. For example, will you be lengthening or shortening the sleeves? Lengthening or shortening the waist? Maybe you’re adding a ribbing to the bottom hem. These are all things that will change the amount of yarn you’ll need. If you’re going to be doing a lot of lengthening, err on the safe side and buy a few extra skeins.

[box type=”shadow”]For more tips on modifying a pattern, see our post on adapting stitch patterns for customized knitting.[/box]

How much yarn would you need to lengthen this 1-hour herringbone cowl?

## 2. If you’re substituting yarn from a pattern

Time for some elementary-school arithmetic! You already know how to successfully substitute yarn, right? To figure out how many yards of your substituted yarn you’ll need, calculate the total yardage from the pattern’s yarn first.

### Use this formula:

Number of skeins x yardage per skein = total yardage needed for pattern

So for example, if your pattern uses three skeins of yarn that each have 240 yards, then multiply three by 240 to get a total of 720 yards.

Be warned: Depending on your substitution, you may need even more yarn. Keep in mind, for instance, that yarns with less elasticity may require less yardage. So if the pattern calls for a yarn that’s a wool-nylon blend and you’re substituting a 100% wool yarn, then you may need to buy more. My rule is to always buy an extra skein just to be on the safe side.

## 3. If you’re designing your own pattern

Our friends at Lion Brand Yarn have this super handy yarn yardage estimate chart that covers yarn yardage for basic garments and accessories like scarves, sweaters, hats and afghans. The chart is even divided by size and yarn weight categories to give you the closest estimation possible.

Another way to estimate is to look up patterns that might be similar to your design. Go through your knitting pattern collection and see if you can find something similar. For example, if you want to make a triangular shawl in a lace-weight yarn, see if you can find a similar shawl in your patterns. How much yarn does that pattern use? That could give you a good idea of how much yarn you’ll need, too.

One thing to watch out for: remember that, as mentioned above, if your design includes something like cables, you’ll need more yarn to make up for those extra twists. Take that into account when you’re referring to existing patterns.

[box type=”shadow”]Learning how to estimate yardage is just one step in becoming a more advanced knitter. Want other ways to advance your skills? Check out Improve Your Knitting with Patty Lyons to learn about different knitting styles and methods that can help you knit faster and even more efficiently.[/box]