How To Knit a Diagonal Rectangle

Learn how to Knit a diagonal rectangle in this tutorial today! In addition, you’ll finish a cute baby blanket while learning this!

I love knitting blankets and I picked this one up on Monday and finished it by the end of the week. All of you loved my corner to corner baby blanket and requested an easy tutorial to make it a rectangle. A rectangle has similar increases and decreases but also a NEW middle area, which I will explain below.

If you have never knit before, start here: How To Knit Beginners Step by Step Photos

how to knit a rectangle using wool ease thick and quick


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You will need a Size 17 US or 12.5mm Circular needle at least 29-inch long for this blanket. Even though it is a circular needle, you need to knit back and forth, and not in the round. The circular needle is simply to accommodate a large number of stitches.

You will need a yarn that works with this size needle, like these yarns. The exact yarn and colorways I have used are listed near the bottom of this post.


In today’s post, I’ll show you how to knit a diagonal rectangle baby blanket in 5 days! The yarn I used here makes it easy to finish this project in a short amount of time.

To knit a diagonal rectangle, you need to work your blanket in three portions- the increase, the middle, and the decrease.

how to knit a rectangle on the bias

Here’s how to knit a diagonal rectangle:

INCREASE: We start with the increase area, here in pink yarn. You start by casting on 1 stitch. And then you work in the following pattern:

Row 1: Knit in front and back of the first stitch, knit till the last but one stitch, knit in the front and back of the last stitch. (We’ve made or created 2 extra stitches in this row)

Next row, and all even rows: Knit all stitches.

Repeat these two rows until you have a triangle whose two sides measure 28 inches (this is the width of our blanket)


MIDDLE: Next is the middle area. This is the area I created with a grey and white stripe. In this portion, we simply grow the blanket, but as we are knitting on the bias we need to increase each row by one stitch and decrease that one stitch at the end of each row. The pattern goes as follows:

Right side: Knit in the front and back of the first stitch, knit till the last two stitches, knit 2 tog (We have maintained the number of stitches on the needle)

Next row, and all even rows: Knit all stitches.

Repeat these two rows until you measure the length to be 40 inches.


DECREASE: We end our blanket with the decrease area, here in yellow/ochre colored yarn. You work in the following pattern now,

Right side rows: Knit 2 tog, knit till the last two stitches, knit 2 tog (We’ve decreased 2 stitches in this row)

Next row, and all even rows: Knit all stitches.

Repeat these two rows until you have two stitches left on your needle. Knit 2 tog to cast off.



And there it is! You just saw how to knit a rectangle, and I hope this tutorial explains it better to you. This blanket took me about 5 days to knit, but it can be easily finished in one long weekend. It is a small blanket, therefore perfectly portable!

Knitting a rectangle on the bias

I finished off the blanket with a single crochet border all around. A darker grey color medium yarn (4) with a size I hook created a bold yet simple edge.

wool ease thick and quick baby blanket

I absolutely loved the color pop of the thin white stripe. I kinda wish I had added the white stripe throughout the blanket instead of just in the middle area. That could be a great option if you were to recreate this!

how to knit a diagonal rectangle


I used 4 colors of yarn for my blanket and they are all Lion Brand Wool-Ease Thick and Quick yarns. This yarn works up very quickly and hence a great choice for quick projects. I also love the colors they come in! This is not a sponsored post, I like to build my yarn stash during sales online.


For this blanket size, I used 1 skein of each of the color Blossom, 1 skein of the color Slate, 1 skein of the color Fisherman, and 1 skein of the color Mustard. That’s a total of 4 skeins to create the stripe pattern that I have. If you were to make this blanket in one solid color you would probably only need 3 skeins. I would say 4 skeins to be on the safer side.

Here is a list of everything I used and you see in this blog post:


changing colors garter stitch how to knit a diagonal rectangle
  1. This blanket can be easily made in different colors to suit what you have in mind. A great option would be to use just grey, white and pink colors. Replace the yellow/ochre area with the pink itself for a more symmetric look. The choice is yours.
  2. If you wish to change this to stockinette stitch, then simply purl all the even rows instead of knitting them.
  3. If you are using a stockinette stitch, you would want to prevent the curling of the blanket fabric. I would recommend, slipping the first stitch of each purl row to prevent this.
  4. If you do not own any chunky yarns and are hesitant to purchase them, try multi-strand knitting. I holding multiple strands of medium yarn together also known as multi-strand knitting
  5. For my color changes, since I used a thin white stripe, I cut the white yarn after each use. However, I did not cut the grey yarn, but carried it up instead.
  6. Gauge isn’t really a main part of this blanket. You can literally pick up your needles and start knitting. Make sure to choose a needle size appropriate for your yarn type.


You can make your knit rectangle as large as you want easily! In other words, you can keep knitting until you are happy with the knit fabric size. Follow these three steps:

  1. Increase the area until you reach the width of your choice.
  2. Once you have reached the width, stop the increase. After that continue building the middle area until the length becomes the size you want.
  3. With the width and length achieved, now all you need to do is decrease. Create the final two corners of the blanket to finish it off.


Thank you for your interest in this How to knit a diagonal rectangle pattern!

Click here to print this knitting pattern or save to your computer.

I enjoyed knitting this rectangle blanket so much! Above all, I’ve loved the whole process- from selecting the yarn, casting on, repeated knitting to casting off.

Now that you have learned how to knit a diagonal rectangle, what will you be knitting with this idea? Let me know in the comments below!


Thank you for being here today and spending some creative time with my friends! I’m so thankful for your kind words and support.

If you recreate this tutorial and share it on social media don’t forget to tag me! @smithakatti #smithakatti

For yarn projects, find me at @smittenbyyarn #smithaknits #smithacrochets

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  1. Thank you so much for this post!! I’ve been trying to find out how to knit on the bias for a while now but all the patterns or tutorials are either all about garter stitch or square shape. Your photos and explanations were perfect! I can’t thank you enough.

  2. Hello Smitha, I’m an experienced knitter, but have never knitted on the bias before. I am designing a lace bias shawl and needed some clear instructions for how to manage the increases and decreases for knitting on the bias. Your writing and instructions are so clear and understandable. Thank you!

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