Before you begin any knitting project, you need to know how much yarn for a long tail cast on. In this Knitting 101, I’ll show you four easy ways to measure for a long tail cast on.
Long Tail Cast On

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When you learned how to cast on stitches, you probably learned the knitting basics of the long tail cast on. A favorite for most knitters, it’s usually one of the first cast-ons any knitter learns. It’s considered a stretchy cast on and works well with many a knitting project.
But no method or technique is without reproach.
The biggest complaint from knitters when using the long tail cast on method is: How much yarn do I need? It’s a great question.
It’s hard to gauge how much yarn to cast on if you don’t know how. The yarn ends up being too short or too long. It can be so frustrating.

But today we’ll resolve this issue so it’ll never be a problem for you again.
In this post I'll discuss four different methods, with pros and cons, to help you decide which is best for you.
Let’s get started so you can get back to knitting.
Long Tail Cast On: How Much Yarn
The four methods we’ll discuss below are:
- Wrapping
- Zig-Zag
- Stitches per Inch (SPI)
- Two-strand Cast On
Yarn Wrap Method
You might already know this method or have heard of it before.
This method is just as the name suggests. In this case, you wrap yarn around the needle the number of stitches you need for your knitting project.

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To determine how much yarn for a long tail cast on, there are a few steps to take:
- First, unravel a small amount of yarn from your yarn ball.
- Second, wrap the yarn around your knitting needle as many times as possible.
- Third, unravel the wrapped yarn marking the distance from start to finish.
Say your stitch pattern calls for you to cast on 20 stitches. When you unravel your yarn from the needle and measure, you have enough for 20 stitches. This would be the amount you would cast on. You also want to add a little extra to account for your slip knot and leave a yarn tail.
With this method, you need to wrap your stitches evenly. Don’t wrap the yarn around the needle too tightly or too loosely. Doing so will affect your measurements.
Yarn Wrap Method Pros:
- This method tends to be more accurate when using fewer stitches.
- Wrapping is a good option for smaller projects.
Yarn Wrap Method Cons:
- You may cast on tighter or looser than you wrap.
- This method is not always reliable.
NOTE: The Yarn Wrap Method is not to be confused with wraps per inch (WPI). WPI in knitting relates to yarn gauge, or the weight of the yarn. It is not a way to measure yarn for long tail cast on.

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Now, let’s talk about the second method for measuring yarn in a long tail cast on: the Zig-Zag Method.
Zig-Zag Method
The Zig-Zag Method is similar to the wrap method. It’s different, though, in that it requires you to cast on stitches.
Here, imagine you have a knitting pattern that calls for you to cast on 100 stitches in the round. You probably don’t want to leave this cast on to chance. I know I wouldn’t. That isn’t to say that it hasn’t happened to me before.
Here’s how you do it:
First, unravel a small portion of yarn. The length isn’t important.
Second, long tail cast on until you reach the end. Then, while holding the loop at the end, unravel these stitches.
Now, fold the yarn and measure out the number of stitches you need end over end. The picture below gives you a better visual of this method.

Say you cast on 10 stitches but you need 60 stitches for your knitting project. Using this method, you would measure out 6 lengths of 10, as shown above.
As you can see, each arrow designates a length. From the yarn tail to end of row 1, this demonstrates one length of ten stitches. You would then measure out five additional lengths for a total of 60 stitches.
Again, don’t forget to add a little extra yarn for your slip knot and enough for a yarn tail.
Zig-Zag Method Pros:
- Quick and easy.
- Pretty accurate.
- Doesn’t require a ruler.
- A good option for projects large and small.
- Less likely to leave you playing yarn chicken.
- Works well on straight and circular knitting needles.
Zig-Zag Method Cons:
- Causes fear in those who hate math.
- Not always exact depending on how you zig and zag.
Now let’s talk about a third way to measure yarn for long tail cast on.
Stitches Per Inch Method
As the name suggests, this method requires you to measure how many stitches per inch. Thankfully, this is simple to do. It requires only a ruler or gauge tool, like the one shown below, and a calculator.

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Say you need to cast on 100 stitches for your project. You would take your ruler and measure out 100 inches of yarn plus a little extra for your yarn tail.
Sounds too easy, right? Read on for pros and cons of this method.
Stitches per Inch Method Pros:
- Requires minimal measuring, but that may not always be a good thing.
- This method often works well with worsted weight yarn.
Stitches per Inch Method Cons:
- The Stitches per Inch Method is not always accurate or reliable.
- This method may leave you with an extra long yarn tail.
- It may require multiple cast-ons to meet your stitch requirement.
- May not work well on all yarn gauges or yarn weights.
Here’s a handy knitting stitches per inch chart.

Before we move on to the next method, I just want to make one thing clear. The Stitches Per Inch Method is not related to knitting gauge. Some knitting topics are confusing because they bleed over or sound related to other tasks.
Finally, let’s discuss the last method in this post: the Two Strand Cast On Method.
Two Strand Cast On Method
This last method has been around for years but, for some reason, isn’t as well-known as the others. This is unfortunate because it is so incredibly useful. You'll see below.
The Two Strand Method requires just a couple of steps:

First, you'll need to make a slip knot. Then, long tail cast on using both ends of a single skein, ball, or hank, etc..

You could also cast on using one strand from two separate yarns. This way gives you a lovely multi-colored edge, as shown below.

How to Do the Two Strand Cast On
First, make your slip knot with both strands leaving a 4" – 6” yarn tail.
Next, slip it onto your knitting needle and tighten it gently. Then, separate the two strands and long tail cast on.

There is an additional step in this method though. You’ll need to cast on one extra stitch. Later, you will remove the slip knot, which is why you add the extra stitch.
When you have cast on all the required stitches +1, cut one of the two strands. Be sure to leave a long enough yarn tail to weave in later.
Now, knit your first row with the uncut yarn strand. When you come to the slip knot, do not work it. Slide it off the needle and undo the knot. From there, continue knitting.
Two Strand Cast On Method Pros:
- Most accurate method.
- Quick and easy.
- No measurement or math involved.
- Doesn’t require any extra tools.
- No knot on your cast on edge.
- Helps you cast on large stitch quantities.
- No fear of running out of yarn.
- Can be worked with one or two colors of yarn.
- Fool proof!
Two Strand Cast On Method Cons:
- You might forget to add the extra stitch or remove the slip knot.
- There’s two extra yarn tails to weave in.
As I mentioned before, this method is really handy, especially if you have a lot of stitches to cast on. This picture below is of the Eenie Meenie Baby Blanket knitting pattern (in two sizes) that I published. I used the Two Strand Cast On Method to take the guesswork out of casting on the 100+ stitches.

Now you know four ways to measure how much yarn you'll need for a long tail cast on. So grab your knitting needles and try them for yourself today.
Did you find this knitting tutorial useful? Tell us about it! Please share a comment below.
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Thank you for explaining this 2 strand cast on method. Wow! Who would’ve thought? I did watch a video on it and she said to cut the strand nearest you. Does it really matter?
I have a question that I hope you know the answer to. I don’t know how to word it in a way to google it. But is there a way to know how long your project will be by the number of your cast ons?
Thank you.
Hi Melissa! Glad you found it helpful.
Yes, it does matter. When you're done casting on and with the needle in your left hand, check to see where the yarn is. If you're going to knit next, the yarn should be in back. If you're going to purl, the yarn should be in front.
Your second question is related to gauge. You can read up on it here: https://knitfarious.com/guide-to-knitting-gauge/
Basically, you'll want to check your gauge before you knit since different stitch patterns will affect the final size of your piece. A good example is stockinette stitch vs. ribbing. They just behave differently.
I hope this helps.
Thanks again for taking the time to leave a comment. 🙂
Another con for the two strand cast on- two extra ends to weave in.
Thank you for pointing this out. I must have forgotten to add it. It has been added.
That being said, yes, you are correct, more yarn tails to weave in. You could always weave in one when you begin knitting and weave in the other later. Anything to make this task more efficient. 🙂
A couple things you omitted. When using the wrap method with sling-shot long-tail co method -- the tail length should be draped over your finger, not your thumb.
Also a con for 2 strand method is that you have 2 tails to weave-in.
Thank you so much for pointing this out. I learned it this way early on and, interestingly, it still seems to produce the same results. I realize the difference now and will be updating my posts to reflect the industry standard.
As for the two-strand method, yes, there’s an additional yarn tail to weave in. That’s already been updated.
I found this very useful. I think the fourth method is the one I will use. Thanks so much
That's great! So glad to hear it. Yes, the 4th method is my preferred method too. Thanks for reaching out! 🙂
Great essay, but I'm too dumb to understand it. We want to knit scarves to keep homeless people warm. I'm thinking 5 feet long and standard width. How many inches of bulky yarn would we need for each scarf? all suggestions appreciated. this is my first day of even thinking about this.
Hi! Well, there are a lot of factors involved (yarn type, needle size, knitting tension) to knitting a "standard width" scarf. I recommend you take a look at this post on how to knit a gauge swatch and start there. Swatching will save you a lot of time and frustration later. I also recommend you weigh your yarn before and after swatching. This, along with the other steps, will help you to more accurately determine how much yarn you'll need for each scarf. Good luck!
The two-strand cast on is a game-changer! Thank you!!!!
Yes! I'm so glad you found it helpful. It's definitely my go-to method. No more playing yarn chicken! 🙂
Cheers!
Ahh, I feel so dumb bc I still can’t figure out four, I think I end to watch a video. I actually want to make cowls for the homeless so they have a choice between a scarf or a hat and scarf. I also read a great article on the hazards of scarves for homeless that unfortunately they have been found strangled with their scarves and that’s why hats ate preferred as well they prefer black bc one it doesn’t show the dirt but that most homeless people prefer black bc they don’t stand out and that was the consensus for homeless women
The fourth method does take a little practice, but I know you can do it. I don't have any video tutorials now but I hope to add them in the near future. In the meantime, do the best you can do and it will be enough. Wishing you success! ~ Christina
I want to say thank you for all your advice. I used to be able to knit fair Ike sweaters in collage, taught myself first thing I ever knitted but do to a brain injury, I canopy knit on circular but patterns and gauges are not doable. I just use a 6 or 8 mm but I have a hard time with the right yarn and the number of stitches and how not to have the bottom and top roll up. Any advice on that, I would so appreciate bc I’ve been looking for help for a long time.
Hi Kimberley! Thanks for your comments. It sounds like you're knitting in stockinette stitch (knit one row, purl one row), which will cause the yarn to roll if there is no border. I'd recommend adding a garter stitch border to whatever you're making to help stabilize the yarn. Seed stitch is another good option, too. I hope this helps! I'm sending you positive vibes and well-wishes for your health. Take care.
I have found that if you take 75% of the number of stitches plus about 4-5" will give you just about the right length you need. This has worked for me with all sizes of yarn.
How interesting! I'll have to try that next time I'm casting on. Thanks for sharing your method, Harriet!
How do you do number 4 when knitting with jumbo yarn (size 7 or 8)? I'm using Bernat Big Blanket and it's impossibly big for me as a newbie but my daughter had asked for a chunky blanket. This is the best yarn I could think of as she is currently in Okinawa and everything is prone to mold so merino is out.
Hi Stefanie! For the two-strand cast on from a single ball of yarn, you'll need to dig around in the center for the inside tail then grab the outside tail. Another way to do this would be to wind the yarn into a cake to make it easy. A third way, and to make it really, easy, is to just use two separate balls of yarn and start from the outside and work in. I hope this helps. Good luck with your chunky blanket!