Knit Squares Blanket Step-by-Step: Checkered Rainbow Layout
There is something deeply satisfying about a blanket made entirely of squares. Each small piece is its own accomplishment — a portable project you can tuck into a bag, work on during a lunch break, and set aside without losing your place in a complicated pattern. When you arrange those squares in a checkered rainbow layout, the finished blanket becomes something spectacular: a riot of color organized into a design that feels both playful and structured, like a stained-glass window you can wrap around your shoulders.
This guide walks you through every step of making a knit squares blanket in a checkered rainbow layout, from choosing your yarn to weaving in the last end. Whether you are a beginner who has only ever knitted rectangles or an experienced knitter looking for a satisfying stash-busting project, this is a blanket worth making.
What Is a Checkered Rainbow Layout?
Before we talk about needles and cast-ons, it helps to understand what the layout actually means. A checkered rainbow blanket arranges solid-color squares in a grid where no two squares of the same color sit directly next to each other — horizontally or vertically. The effect is a checkerboard pattern, but instead of just two colors alternating, you cycle through the full rainbow spectrum across the blanket.
Imagine laying out your squares like this: the first row starts with red, then orange, then yellow, then green, then blue, then violet, then red again. The second row starts with orange, then yellow, then green — each color shifted by one position. The third row starts with yellow, and so on. From a distance, the blanket appears to travel diagonally through the rainbow, with each “diagonal stripe” being a single color, but because the squares alternate with their neighbors, the overall impression is a dazzling, vibrating checkerboard of pure color.
You can adapt this principle to use as few as two colors (for a classic checkerboard) or as many as twelve or more (for a dense, complex rainbow). The instructions below use seven colors — the traditional ROYGBIV spectrum — which creates a rich, balanced blanket.
Materials You Will Need
Yarn: Choose a smooth, worsted-weight yarn in seven colors. For a lap blanket approximately 42 by 42 inches, you will need roughly 200 yards of each color, totaling around 1,400 yards. For a throw blanket around 56 by 56 inches, plan for approximately 400 yards per color, or 2,800 yards total. A smooth yarn in 100% wool, a wool-acrylic blend, or a cotton-acrylic blend works best because the stitches show up clearly and the fabric has good drape. Avoid very fuzzy yarns for your first attempt — they make it harder to count stitches and see your work.
Needles: Size US 7 (4.5mm) or US 8 (5mm) straight or circular needles work well with worsted weight yarn. If you prefer double-pointed needles or interchangeable circulars, those work too. The important thing is that your gauge feels comfortable and produces a fabric that is not too loose and floppy or too stiff and dense.
Notions: A yarn needle for weaving in ends and seaming, scissors, stitch markers (optional but helpful), a ruler or measuring tape, and blocking pins or blocking wires if you plan to wet block your finished squares.
A note on gauge: For this project, precise gauge is less critical than consistency. Each individual square should measure the same size as every other square. Work a swatch, measure it, and adjust your needle size if needed until your square comes out even and lies flat without curling dramatically at the edges. Most knitters working at a standard worsted weight gauge produce a square of about 6 by 6 inches on US 7 or US 8 needles with around 20 stitches cast on, but your hands may differ.
How Many Squares Do You Need?
This depends on the size of your finished square and the size of blanket you want. Here is a simple formula: divide the desired blanket width by the square size to get the number of squares per row, then do the same for the length.
For a 42-inch-wide blanket using 6-inch squares, you need 7 squares across. For a 42-inch length, you need 7 squares down. That gives you 49 squares total. With 7 colors in a shifting checkerboard pattern, 49 divides evenly, so the color arrangement works out beautifully with 7 squares of each color.
For a 56-inch-wide throw using 6-inch squares, you need about 9 to 10 squares across and 9 to 10 down, giving you 81 to 100 squares. If you want the color sequence to work out evenly, choose a number of squares per row that is a multiple of 7 (so 7 or 14), or be prepared to have some colors appear slightly more often than others — which is perfectly fine and adds visual interest.
Knitting Each Square
The individual squares are knitted in garter stitch, which means you knit every single row. Garter stitch creates a squishy, reversible fabric that lies flat without blocking and has a lovely ridged texture that reads beautifully in a grid of colors.
Casting on: For a 6-inch square at standard worsted gauge, cast on 24 stitches. (If your gauge swatch showed you that you need more or fewer stitches to reach 6 inches, adjust accordingly.) Use a long-tail cast on or a knitted cast on — both give you a tidy edge that looks good when you seam the squares together later.
Knitting the body: Knit every row until your piece measures 6 inches from the cast-on edge. This will be approximately 48 to 52 rows of garter stitch. Do not count the rows obsessively — just measure with your tape measure and trust what you see.
Binding off: Use a standard bind off or a stretchy bind off. Knit two stitches, then pass the first over the second. Continue across the row until one stitch remains, then cut your yarn, leaving a 6-inch tail, and pull it through the last loop. Your square is done.
Make as many squares as you need, repeating this process in each of your seven colors. Some knitters like to make all their squares in a single color before moving on to the next. Others prefer to rotate through the colors as they go, which keeps the project feeling varied. Either approach works.
Blocking Your Squares
Blocking is the process of wetting your knitted pieces and gently stretching them to their final measurements while they dry. It is optional but highly recommended for this project because it evens out the tension across each square, makes the edges tidier, and most importantly, ensures that all your squares end up exactly the same size. A slight difference in size between squares will create puckering and distortion when you seam them together.
To block, soak your squares in cool water for about 20 minutes until fully saturated. Gently squeeze out the water — do not wring — and lay each square on a foam blocking mat. Use T-pins to pin each corner to the exact same measurements: 6 by 6 inches, or whatever your target size is. Let them dry completely before unpinning, which usually takes 12 to 24 hours depending on humidity.
If you are working with an acrylic yarn, wet blocking will not permanently set the stitches the way it does with wool. For acrylic, you can steam block instead: hover a steam iron a few inches above the surface of the square (do not press the iron directly against the yarn) and let the steam relax the fibers. Pin immediately and let cool.
Planning the Checkered Rainbow Layout
Before you start seaming, lay all your squares out on a large flat surface — a bed, a clean floor, or a design wall if you have one. Arrange them in the shifted checkerboard pattern described earlier.
Here is a concrete example for a 7-by-7 grid using colors labeled 1 through 7 (Red, Orange, Yellow, Green, Blue, Indigo, Violet):
Row 1: 1, 2, 3, 4, 5, 6, 7
Row 2: 2, 3, 4, 5, 6, 7, 1
Row 3: 3, 4, 5, 6, 7, 1, 2
Row 4: 4, 5, 6, 7, 1, 2, 3
Row 5: 5, 6, 7, 1, 2, 3, 4
Row 6: 6, 7, 1, 2, 3, 4, 5
Row 7: 7, 1, 2, 3, 4, 5, 6
Each color appears exactly seven times, and no two adjacent squares share a color. The diagonal streaks of each color run from the upper right to the lower left, giving the blanket a sense of movement. You can reverse the direction of the shift (starting each row one later instead of one earlier) to make the diagonals run the other way.
Photograph your layout before you start seaming so you can refer back to it if squares get moved around.
Seaming the Squares Together
There are several methods for joining knitted squares, and each creates a slightly different look. Here are the three most popular options for a blanket like this one.
Mattress stitch seam: This is an invisible seam worked with a yarn needle, joining two pieces along their edges with a ladder-like motion. It creates a nearly seamless join that lies flat and flexible. Use a neutral color or match the color of one of the squares being joined. Work with the right sides of both squares facing you. Insert the needle under one bar between stitches on one piece, then the corresponding bar on the other piece, and pull snug. Continue along the entire edge, then weave in the tail.
Whip stitch seam: Faster than mattress stitch but slightly more visible, the whip stitch passes the yarn over the edges of both pieces repeatedly. You can work it with the right sides together (so the seam is hidden inside) or with the wrong sides together (so the seam becomes a decorative ridge on the front). The ridge version, worked with a contrasting color, can become a design feature — it adds an extra graphic element to the checkerboard pattern and is very popular in patchwork-style blankets.
Crochet slip stitch seam: If you know even basic crochet, a slip stitch seam is fast and sturdy. With a crochet hook and yarn, work a slip stitch through both edges simultaneously. This creates a flat, strong seam and is especially useful if you want to add a crochet border later.
Assembling the blanket: The most common approach is to seam the squares into horizontal rows first, then seam the rows together. This gives you manageable pieces to work with and lets you check your color layout as you go. Pin or clip the squares together before seaming to keep them aligned.
Adding a Border
A border is not strictly necessary, but it gives the blanket a polished, finished look and can help stabilize the edges. The simplest border is a garter stitch border worked by picking up stitches around the entire perimeter of the blanket and knitting back and forth for 6 to 10 rows before binding off.
To pick up stitches along the edge: with the right side facing you, insert your needle into the edge of the blanket, wrap the yarn around the needle, and pull through a loop. Space your pick-up points evenly — roughly one stitch for every two rows of garter stitch along the sides, and one stitch for every cast-on or bound-off stitch along the top and bottom edges. At the corners, pick up two or three extra stitches so the border can turn the corner without puckering.
You can work the border in a single neutral color like white, cream, or black, or in one of your rainbow colors. Some knitters like to add a striped border, working a few rows in each rainbow color in sequence, which creates a colorful frame around the whole blanket.
Finishing and Care
Once your border is complete, weave in all remaining yarn ends. Thread each tail onto your yarn needle and work it back and forth through the stitches on the wrong side of the blanket, changing direction at least twice to lock it in place. Trim the ends close to the fabric.
Give the finished blanket a final blocking if you want it to look its absolute best. Soak it, squeeze out the water, and spread it flat to dry. You will be amazed at how much more luxurious and even it looks once the fibers have relaxed and settled.
For care instructions, follow the guidance on your yarn label. Most wool or wool-blend blankets can be hand washed in cool water with gentle soap and laid flat to dry. Many acrylic blends are machine washable on a gentle cycle, which makes them practical for everyday use and especially good choices for baby blankets or gifts that will see heavy use.
Tips for a More Successful Project
Work consistently. If your tension tends to change when you are tired or anxious, save your knitting for moments when you are relaxed. Uneven tension is the primary reason knitted squares come out slightly different sizes, and blocking can only do so much to compensate.
Keep a simple tally of how many squares you have completed in each color. It is very easy, when you are making forty-nine squares over several weeks, to lose count and accidentally make nine reds and only five indigos.
Embrace imperfection. Handmade textiles have slight variations, and those variations are part of their beauty and value. A blanket that took you 60 or 80 or 100 hours to make will be cherished precisely because it was made by human hands.
Consider making extra squares. Knitting one or two bonus squares in each color takes only a small amount of extra time and gives you flexibility if a square gets damaged, if you decide to make a larger blanket, or if you simply want to experiment with a different layout arrangement before committing to seaming.
Why This Project Is Worth Every Stitch
A checkered rainbow knit squares blanket is one of those projects that earns its place on the list of all-time great knitting projects. It is genuinely beginner-friendly because the skill required for each individual square is minimal — just casting on, knitting every row, and binding off. At the same time, it scales beautifully in ambition: experienced knitters can use it as a canvas for experimenting with yarns, textures, and color theory, swapping out plain garter stitch squares for mitered squares, seed stitch squares, or textured cables.
The modular nature of the project means you can work on it in tiny increments without ever feeling lost or overwhelmed. Every square you finish is a small, complete victory. And when you lay them all out on the floor and see the rainbow checkerboard taking shape before you start seaming, there is a moment of pure visual delight that makes the whole investment of time feel completely worthwhile.
Whether you make this blanket for yourself, for a new baby, for a friend who needs a little color in their life, or simply because you have a basket full of yarn in every shade of the rainbow and you finally know what to do with it — start knitting. One square at a time, you will build something genuinely beautiful.
