How much yarn do you need for a blanket?

A tutorial on how to calculate yarn the requirements for different kinds of blankets – from baby blankets to chunky throws.

Do you want to decorate your home with a wonderful handknit throw or a big afghan? Does one of your loved ones expect a baby and you want to knit them a nice baby blanket? But now you want to go shopping for yarn and you just don’t how much yarn you need for a blanket, right?

Well, then you came to the right place. In this tutorial, I’m going to show you exactly how to calculate your yarn requirements the right way – no matter the size of your blanket. It’s not hard at all, but you will need a calculator. But don’t be afraid, I’ll take you by the hand and show you the process step by step.

Reading tip: Here’s how to pick the right yarn for knitting and choose the best color combinations. I also wrote a detailed guide on calculating yarn requirements for a scarf the right way.

Calculating how much yarn you need for a blanket

Now, you probably came here and might have expected to find concrete answers. Like, for a baby blanket you need 1.500 yards of yarn and for a big throw 3.500 yards.

I won’t give you these ready answers because they are a dead-end! Maybe you are a knitting beginner (make sure to check out my free knitting school) and you are looking for these easy answers. In this case, there are blanket knitting kits* with all the yarn you will need and the pattern.

They are usually totally a bit expensive and that’s not why you are here, eh? What I need you to understand is that how many skeins of yarn you need for a blanket totally depends on three factors: The yarn weight you choose, the pattern you pick, and the size. It makes a big difference if you knit your blanket with dk weight yarn or a super bulky yarn.

*I earn a small commission for purchases made through links in this article

Blankets are big projects. Even baby blankets will take quite a couple of hours. So, I really advise you to plan the projects with care and not just rush into a yarn store, tell them you want to knit a blanket, and throw your money at them. Here are two options you have:

With a super chunky yarn in simple stockinette stitch you might only need 600 yards and with fine lace yarn and cable stitch, maybe 3000 yards or more. And no calculator in the world will be able to answer this properly. You always end up overbuying or ending up with too little yarn. And that’s probably not what you are looking for.

#1 Knitting a swatch

Simple blankets are like scarves. You can basically pick a nice knitting stitch pattern, cast on stitches, and get going without a pattern. BUT I absolutely urge you to knit a swatch. So, what you should do is, go to a Local Yarn Shop or buy some nice yarn online and buy just one skein.

And then, knit a little swatch with it – say 8×8 inches (20x20cm) in the stitch pattern of your choice. Make it fairly big, cast off, and wash it once. Why? Most yarns change after washing, some more, some less. If you knit something like a baby blanket, then you will end up washing it quite often. So, it would be a pity if it ended up being twice as large after washing or totally felted and unsightly!.

Then, you can measure the swatch, and put it on your kitchen scale. And the rest is just easy math. Here’s an example.

1. Find out the exact yarn requirements of your swatch: Let’s say it’s 8 inches wide and 8 high and weighs 1oz. That means you need 1 ounce per 64 square inches (multiply the width by the height).
2. Find out the total area of your blanket: Say you want it to be 40 inches wide and 70 inches high. That would be 2800 square inches.
3. Divide the total area of your blanket by the area of your swatch: So, in this example, this would be 2800/64 = 43.75.

Since you know that you needed one ounce for the swatch, the factor will tell you how many ounces you will need for your blanket. Round it up liberally and then you can go buy the required amount. Make extra sure they are from the same dye lot! Yarn is dyed in lots/big batches, and skeins from a different lot will often have a slightly different hue and it WILL show. You don’t want that.

In this case, I would probably go for around 46 ounces. Why? Mistakes happen or you might want to add a little border later on to prevent curling. Also, a bit of spare yarn to do some mending is always a nice idea, right?

I know, a lot of beginners shy away from knitting swatches, because it’s essentially extra work you will have to unravel straight away. But, it will save you money and time. Because maybe, as you knit your little swatch, you realize that the pattern or the yarn doesn’t look the way you imagined it would be. If you only bought one skein, you can still make a different/better decision.

#2 Buying a pattern

If that sounds too complicated for you, then you do have another choice. You can buy a knitting pattern (here’s a direct link to Etsy with many beginner-friendly blanket patterns). There are thousands of really nice blanket patterns out there. And almost all of them will tell you exactly how much yarn you will need.

But here’s the catch. Typically, a pattern will tell you how much of a specific yarn you need. If you don’t want to or can’t get the same yarn, then you will have to knit a swatch as well to meet the gauge of the pattern and do similar calculations as above if you are off.

Other things to consider

The beauty of this technique is really that it’s the same for all types and sizes of blankets. No matter if you are planning to knit a blanket with chunky yarn or loop yarn. It always boils down to knitting a swatch or buying a pattern kit.

If you already have a nice blanket you want to recreate in a different color/yarn, you could also weigh that existing blanket and use it as a rough estimation of the amount you will need for the next project. But unlike swatches, that’s not 100% reliable.

You could also look for a similar pattern with a similar yarn and do some rough guestimations. I’m all for taking risks and heading right into the knitting. But blankets do take time. Some big blankets take half a year to finish, while the big chunky blankets need a lot of really expensive yarn. I don’t think that’s the perfect circumstance to be impatient.

Anyway. That’s how to calculate how much yarn for a blanket you will need. Feel free to comment below in case you have any specific questions.