Stop Hating Your Knitting: A Tale of the Long Tail Cast On

Last weekend–just in time for the MDK sale–I was cleaning off my home desk and found a stack of work receipts that I needed to submit for reimbursement (I’m working from home so haven’t been in the office.) None of them were significant on their own but added up they came to a nice chunk of change. Then a friend reminded me that she owed me money. And my state tax return (not big) that I had forgotten about showed up in my bank account. It was almost enough for the Kaffe Stripey Blanket kit and I threw caution to the wind and bought it.

In that caution throwing moment, I forget that it was going to involve casting on 252 stitches. Yikes! Or maybe not. I have a little technique that I use to figure out how long the tail needs to be for a project like this. Since the universe was so kind to me, I thought it would be a good idea to share it with you. There’s math but it’s all spelled out. The only rule is to measure your yarn VERY loosely.

Are you ready? Let’s go.

Grab your yard stick (or measuring tape or ruler) and measure out 18 inches of yarn. Loosely.

Now pinch the yarn at the 18 inch point. That’s where you want to place your needle to start the cast on. You’ll have an 18 inch tail in front and the ball of yarn in back.

Cast on as many stitches as you can comfortably do. Don’t try to max it out. You want a tail that you can sew in. Don’t do that fiddly thing to eek out a few more stitches. As soon as the tail is too short to hold onto comfortably you are done with this step.

Grab the yard stick again and measure the tail.

In this case, my tail is 6.75 inches.

Now count the stitches. I got 27.

Now here’s the math. (A lot of people don’t like math. You can do this. If you just start at the beginning and go step by step it makes sense.)

So I started with 18 inches.
My tail was 6.75 inches.
That means I used 11.25 inches for the stitches. (18 - 6.75 = 11.25)

I got 27 stitches on the needle with that 11.25 inches of yarn.

I need 252 stitches. Now divide that by 27.

252/27 = 9.33

Let’s round that up a smidge and call it 9.5.

So I’m going to need 11.25 inches 9.5 times.

11.25 * 9.5 = 106.875. Let’s just call that 110 inches.

Add back the tail and a little wiggle room (1.25 inches in this case)

110 + 6.75 +1.25 = 118 inches

That’s how much yarn I need (in theory) to achieve a successful long tail cast on.* Measure it out get to casting on.

And there you have it. A 252 stitches on the needle without no gnashing of teeth or pulling of hair.

*Read this, it’s important. I had enough here and the cast on worked but I prefer a longer tail when I’m done. I should have added more wiggle room in the final number but the phone rang while I was doing it. Ideally it should have been 5.25 inches of wiggle room instead of the 1.25 I used. It’s fine. It worked but if I do it again (and for the follwing math) my total tail length for the cast on should be 122 inches to have be dead-on perfect.

This is Rowan Felted Tweed. There are certain yarns that are my “house” yarns that I don’t do my usual hard core stashing (zip locks, labels, Ravelry, etc.) for. I keep them in tote bags on hooks inside the door of my knitting closet. I’m going to do one more bit of math because I use this yarn often.

To cast on 252 stitches on a size five needle in Rowan Felted Tweed, my tail length should be 122 inches. To get a per stitch amount just do some really simple division – divide the number of inches by the number of stitches.

122/252 = .48413

Every fiber of my being wants to say “round this up to half an inch per stitch” but don’t do that. Wait for your next project. Let’s say you have to cast on 120 stitches. Multiply that by the per stitch amount.

120*.48413 = 58.09

I can pretty safely say I’ll need 58 inches for my cast on tail. If I had rounded to .50 I would have come up with the 60 inches which in the grand scheme of things is not that much of a difference but anyone who has played yarn chicken on a bind off will fight you on this one. So an index card with the needle size and the per stitch amount will get popped into the bag with the Felted Tweed on the closet door.

The small print: this usually works but once in a blue moon, things go rogue. If we learned anything from the movie Titanic is the more you say something never fails, the more likely it is to fail.

Happy Knitting.


Thank you, I wish I had know this when I was casting on 356 stitches for a top down shawl.

Wow!!! This is TERRIFIC!!! Thank you for taking the time to write all that out and explain it. It will be a huge help in the future!! Thanks!

I am knitting a scarf lengthwise that has 450 stitches cast on. I cast on using long tail cast on from the middle and outside of my skein. The only problem was my yarn really twisted. But at least I didn’t run out of yarn. I have also cast on 10 stitches and then pulled it out to see how much Yarn used. If it took 8 inches of yarn to cast on 10 stitches then I would just measure out 8 inches per 10 stitches needed. I would just count by tens using my 8 inches.


I use both of these methods too, and sometimes 2 separate balls


I’ve used this method for the mood cardigan body cast on and it worked pretty well…I had an extra long tail but not as long as it was when I cast on the first time and had WAY too much tail.

Too much math and futzing when I just want to get knitting. I use both ends of the skein. Soooo much easier!


What a great post. Thanks!

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Harder than it has to be, folks. For aran, worsted, DK and sport, allot 1 inch per stitch needed to cast on. For fingering and lace, one inch for every two stitches wanted. For bulky, allow 1-1/2”, or 3” for every two stitches. Been doing that for over 50 years.


Holy mackerel! And wow!

I think the easiest way is to just wrap your needle with the same number of stitches you are going to need and add a bit for caution. If it’s a lot of stitches, wrap say 10 or 20 and calculate what you will need from that.

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