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Which yarn should I use?

Sep 14, 2012

In this challenging economy, we all need to save pennies wherever we can. One of my money-saving techniques is to knit from my stash whenever I can.

So much yarn, so little time!

A few years ago, when the money was flowing a little faster, I changed my stash acquisition methods from buying a couple of skeins here and there to buying sweater-quantity. This really helped my stash grow from "What can I do with 400 yards of this yarn?" to "Which sweater do I want to knit with this yarn?" A much better place to be for this sweater knitter!

This approach means that I need to substitute yarns quite a bit. A calculator is my best friend in these cases, as well as knowing the math for calculating yarn substitution, of course.

Vicki Square's book The Knitter's Companion is a favorite of mine, and it contains a section on calculating yardage for yarn substitution. Here it is:

Formula for Interchanging Yarns

Yarns of similar weight and similar texture can generally be interchanged effectively. But there can be a large range in length between balls of two different yarns of the same weight, depending on the fiber type, number of plies, and tightness of the twist.

The number of balls required times the number of yards (or meters) per ball = total number of yards (or meters) needed.

The total number of yards (or meters) needed divided by the number of yards (or meters) in one ball of substitute yarn = number of balls needed of substituted yarn.

For example, if 12 balls of the required yarn have 145 yards (133 meters) each, then the total number of yards (meters) you'll need is:

12 balls x 145 yards = 1740 total yards.

If you want to substitute a yarn that has 163 yards (149 meters) per ball, then you'll need:

1740 total yards / 163 yards = 10.67 balls.

Because you must buy full balls of yarn (and because it's always a good idea to have a little extra yarn) you'll want to buy 11 balls of the substitute yarn.

—Vicki Square, The Knitter's Companion

If you're in a yarn shop and you need to figure this out, don't forget about the calculator on your phone! I use mine all the time for "knitting math."

This handy formula is just one of hundreds of helpful bits of advice for knitters in The Knitter's Companion. Get your copy now—it's on sale for less than half-price!


P.S. Do you have a favorite knitting book? Share it with us in the comments!

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saltscapes wrote
on Sep 17, 2012 5:47 PM

I'm pretty good at math, but what do you do when the yarn in your stash doesn't have a yardage measure printed on the label?  Doing up a swatch will tell me more or less if the substitution is compatible, but how do I know if I have enough yarn to complete the project?

I.Jane D. wrote
on Sep 16, 2012 11:04 AM

I enjoy your info and comments. Sorry that I missed the time for  the bargain on Knitter's Companion, I don't need the disks,only text. Jane D.

kenamaria wrote
on Sep 16, 2012 11:02 AM

Hi Kathleen

It is very useful to know how to calculate de yardage substitute yarn. My big  problem is how to recalculate the number of stitches  in the first row of the yoke when I want to start knitting a top down sweater. I would like to have more information about this matter in the Knitting Daily.



Nancy W wrote
on Sep 16, 2012 7:37 AM

I understand the math.  What I have a problem with is figuring out what size needles I need when I use two different yarns together for a scarf where the pattern only calls for one yarn.

valdaly wrote
on Sep 15, 2012 6:27 PM

I have found that if the yardage AND the weight are comparable I can pretty safely substitute one yarn for another. Adds another level of math but works well.  For instance, if a 2 oz. ball of yarn has 80 yards, and a different yarn is 3 oz. with 120 yards, the diameters of the yarns tend to be about the same.

MSueM wrote
on Sep 15, 2012 1:48 PM

I agree with Janice.  I can do and have done the substitution math, but it would be interesting to see a comparison of different yarn weights/needles get the same effects.  I have done a few swatches, but generally if I'm knitting from my stash there's not always enough to knit several swatches.

Thanks for the good topics, Kathleen!!  I enjoy your posts.

Mary Sue

on Sep 14, 2012 2:13 PM

I've corrected the blog to include the calculation for the yardage of the substitute yarn.

Sorry about the omission!


greatharry wrote
on Sep 14, 2012 11:11 AM

I don't find it difficult to determine if I have enough yardage of yarn in my stash to

make a particular garment.  My problem is how to determine if the yarn is the right weight, type etc. for the garment.  I would love to have some information on Knitting Daily about this topic.

Janice C. Paul

denredmond wrote
on Sep 14, 2012 10:44 AM

Hi Kathleen,

Vicki gives sound mathematical advice about recalculating the amount of yarn needed; however, the bulk (change in thickness) of the selected yarn also needs to be considered. Its not enough to do the metre (yard) math - a swatch will also need to be made to get the best approximation of quantity. This will not only show width and height, but also thickness and draw-in (whether the yard pulls in or lies flat.)

Poetmom wrote
on Sep 14, 2012 10:15 AM

I love the drawing--a good way to visualize the math! But the yardage is missing for the substitute yarn--so it's not clear why we need only 11 balls.

on Sep 14, 2012 10:04 AM

Very good advice, which I need to apply...but I find knitting such an expensive hobby that I tend to veer toward sewing garments, which is much faster and generally cheaper. For example, I'm making a shell, the fabric cost me about $'s basically an overnight project from start to finish. I don't get that insty gratification with knitting, I'm afraid, it's much more of a long haul, and I'm not much of a hat or scarf knitter. Still, I love me my knitting needles!