One of the most common question knitters have 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 Knitting 101, I’ll show you four easy ways to measure for a long tail cast on. I'll discuss the different methods, along with their pros and cons, to help you decide which is best for you and your knitting project.
Please note, this post requires a working knowledge of how to cast on stitches. You can find the long tail cast on tutorial here.
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. It’s a favorite for most knitters. It’s also one of the first cast-ons most knitters learn. The long tail cast on is a stretchy cast on and works well with many knitting projects.
But no method or technique is without reproach. The central complaint on this knitting technique has to do with yarn lengths. You can guesstimate all you want, but it’d be better to have a true go-to method that works for you.

Let’s get right to these knitting techniques so you can get back to knitting.
How to Determine Long Tail Cast On Length
There are four cast on knitting methods we’ll use to determine how much yarn for the long tail cast on. They are:
- Yarn Wraps Method
- Zig-Zag Loops Method
- Stitches per Inch (SPI) Method
- Two Strand Cast On Method
Yarn Wraps Method
You might already know this method or have heard of it before. As the name suggests, you wrap yarn around the needle the number of stitches you need for your project. Let me show you how.

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To determine how much yarn for a long tail cast on using the yarn wraps method, follow these steps:
- First, unravel a small amount of yarn from your yarn ball.
- Second, wrap the yarn around your knitting needle as many times as the number of stitches required to cast on.
- Third, unravel the wrapped yarn marking the distance from start to finish.
If your stitch pattern calls for 20 stitches, make 20 yarn wraps around the needle. When you unravel your yarn from the needle and measure, you should have enough to cast on 20 stitches. You also want to add a little extra to account for your slip knot and leave a yarn tail.
Yarn Wrap Method Pros:
- It doesn't require a ruler.
- Works best on straight knitting needles.
- More accurate when casting on fewer stitches.
- Wrapping is a good option for smaller projects.
Yarn Wrap Method Cons:
- This method is not always reliable.
- Doesn't work well on circular knitting needles.
- You may cast on tighter or looser than you wrap.
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 (thickness) 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 Loops Method.
Zig-Zag Loops Method
The Zig-Zag Method is similar to the wrap method. It’s different, though, in that it requires you to cast on stitches to measure.
With this method, imagine you have a hat 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 length of yarn. The length isn’t critical. You just need to be able to cast on at least 10 stitches.
- Second, long tail cast on until you can't cast on another stitch.
- Now, while holding the loop at the end, unravel these stitches.
- Then, 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 a scarf knitting project. Using this loops 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 the 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 to estimate yarn lengths.
- Pretty accurate and doesn’t require a ruler.
- A good option for any size knitting projects.
- Less likely to leave you playing yarn chicken.
- Works well on straight and circular knitting needles.
Zig-Zag Method Cons:
- For those who hate math, some minor mental math is required.
- Not an exact science and results may vary depending on how you zig and zag.
Now let’s talk about a third way to measure yarn for the long tail cast on.
Stitches Per Inch Method
This method requires you to measure how many stitches per inch. Thankfully, this is really easy to do. The stitches per inch method requires only a ruler or gauge tool, like the one shown below, and a calculator. This is how you do it.

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Say you need to cast on 200 stitches for a cowl knitting pattern. With your ruler, measure out 200 inches of yarn plus a little extra for your yarn tail.
Sounds too easy, right? Read on for the pros and cons of this method.
Stitches per Inch Method Pros:
- Requires minimal measuring.
- Works well with worsted weight yarn or thinner yarns.
Stitches per Inch Method Cons:
- Requires a knitting tool.
- Not always accurate or reliable.
- It may require multiple cast-ons to get it right.
- Doesn't work well on all yarn gauges or yarn weights.
- May leave you with extra yarn in your long tail cast on.
Here’s a handy knitting stitches per inch chart.

NOTE: The Stitches Per Inch Method is not related to knitting gauge.
You can learn more about knitting gauge here.
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 yarn skein, yarn cone, or yarn hank, etc..

You could also cast on using one strand from two different yarn colors. This way gives you a lovely multi-colored edge, as shown below.
Read on for the tutorial!

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.
Again, you can find the Long Tail Cast On Tutorial here.

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.
Helpful Tips:
* If you're using two yarn colors and knitting flat, the yarn in front (on your thumb) will be the smooth cast on edge.
* If you want to cast on in the round with a color different from the body of a knit hat or cowl, use two ends / balls of a single color. See my Lazy River Cowl example below. Then switch to the other color after you've finished casting on.

Get the Lazy River Cowl pattern here.
Two Strand Cast On Method Pros:
- Quick and easy.
- Most accurate method.
- Doesn’t require any extra tools.
- No knot on your cast on edge.
- No fear of running out of yarn.
- No measurement or math involved.
- Helps you cast on large stitch quantities.
- Can be worked with one or two colors of yarn.
- Fool proof!
Two Strand Cast On Method Cons:
- There’s extra yarn tails to weave in.
- You might forget to add the extra stitch or remove the slip knot.
- If you have a large amount of stitches to cast on, the yarn may begin to coil up on itself.
As I mentioned before, this method is really handy, especially if you have a lot of stitches to cast on. This picture below shows my Eenie Meenie Baby Blanket knitting pattern. I used the Two Strand Cast On Method to take the guesswork out of casting on 100+ stitches.

This wraps up our Knitting 101 on how much yarn you need for a long tail cast on. You’ve learned four different methods and their pros and cons.
So, grab your knitting needles and yarn and try them out for yourself and see what works best for you. One of these methods (or more!) is sure to work well for you.
Did you find this knitting tutorial useful? Tell us about it! Please share a comment below.
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!
You omitted the whole part that talks about casting on, and how to cast on with both yarns! You went from making the slipknot with both colors, to a photo with the sentence "now cast your yarn on". What on earth. What do I do with both yarns? how do I control what yarn makes the straight color, and which yarn will continue on to the full color of the hat?
Am i missing a link here, that actually shows you how to work both yarns, that isn't just the sentence "now cast your yarn on"??
Hello. Thanks for your comment. There's a separate post on how to long tail cast on here if that helps you. I did go into the two strand cast on tutorial a little further down. Maybe you missed it? Sorry for the confusion. I've added some further explanation to the post to clarify a bit. Thanks.
As to your question, are you knitting flat or in the round? Do you just want the cast on edge to be one color and the hat to be another? If knitting in the round, just cast on with the single color, then knit with the other color after you've cast on. Good luck!
Great article. Very clear and informative. I have a few hundred stitches to cast on and the two strand cast on method will be perfect. Just what I was looking for!
Thank you so much! I'm happy you enjoyed it!
I learned to knit about 15 years ago.i never came expert at it and have had to forgo a few projects because of it. But on to my elementary question: what is the reason to do a long tail cast on? I just leave a few inches of yarn... usually too much so I clip it before weaving it. I just came across your website and will be back. I'm going to knit one of your hats for a friend.
Thank you. Billie
Hi Billie! The long tail cast on is an elastic cast on that works really well for so many projects. It's stretchy and looks good. When using this method, you leave a long tail so that you have enough to weave in the yarn tail later. I used to have the same problem with too long of a long tail until I found a few ways to prevent this from happening. I've shared my tips in this post. I hope it's useful to you.
I'd love to see your hat when you're done. Happy knitting!