How to Join Granny Squares for a Crochet Bag {Free Template!}

There is something deeply satisfying about a pile of finished granny squares sitting beside you, all different colors, all waiting to become something beautiful. If you have ever made a crochet bag using granny squares, you already know the magic. But if you are just starting out, you might be staring at that colorful pile and wondering: how do I actually put these together? What is the best method? Will the seams look messy? Will the bag hold its shape?

This guide is going to walk you through everything you need to know about joining granny squares for a crochet bag, from choosing the right joining method to finishing your bag with confidence. There is a free template included so you can plan your layout before you ever pick up your hook. Let us get into it.

Why Granny Squares Make the Perfect Bag

Before we dive into the joining techniques, it is worth taking a moment to appreciate why granny squares are such a wonderful choice for a crochet bag project.

Granny squares are modular. You can make them anywhere, stash them in a project bag, pull them out on the train or during a lunch break, and slowly build up a collection over days or weeks. There is no large piece to lug around, no complicated stitch pattern to remember mid-row. Each square is its own small, satisfying project.

They are also endlessly customizable. You can use a scrappy, rainbow color palette with one square per color, or you can stick to two or three tones for a more structured, modern aesthetic. You can make all your squares the same size or mix large and small squares in a patchwork style. The design possibilities are genuinely limitless.

And practically speaking, a finished granny square is already a fairly dense, structured piece of fabric. When you join them together and add a lining, you get a bag that holds its shape beautifully and can handle real-world use.

What You Will Need

Before you start joining, gather everything you need so the process flows smoothly.

For the squares themselves, you will want to use a yarn that is appropriate for bags. Cotton yarn is a popular choice because it is sturdy, washable, and comes in a wonderful range of colors. A medium-weight cotton, also called worsted weight, works well and creates squares that are typically around four to five inches depending on your tension. You can also use cotton-acrylic blends, jute, or even a bulky cotton for a chunkier look.

Your hook size should match your yarn. Most medium-weight cotton works well with a 4mm or 5mm hook, but always check your yarn label and make a test square first.

You will also need yarn in your joining color. You can use one of the colors already in your squares for a tonal look, or choose a contrasting neutral like cream, black, or grey to make the join lines a visible design feature.

Other supplies include a yarn needle with a large eye for weaving in ends and for any slip stitch or flat joins, scissors, pins or locking stitch markers for holding squares in place while you join, and a crochet bag lining if you plan to line your finished bag (highly recommended for functionality).

How Many Squares Do You Need?

This depends entirely on the size of your bag. Here is a simple way to figure it out.

First, make one test square and measure it after blocking. Let us say your square measures five inches.

A small everyday tote bag might use a layout of three squares wide by four squares tall for each side panel, giving you six squares per side, twelve for the body, plus however many you want for the base and handles. A larger market bag might go four wide by five tall.

For a simple structured tote using five-inch squares, a common layout is:

Two side panels, each three squares wide by three squares tall, giving you eighteen squares for the sides. One base panel of three squares by one square, giving you three squares. That comes to twenty-one squares for the main body. You can then add a strip for the sides and base gusset if you want a boxier shape.

Use the free template at the bottom of this post to sketch out your layout and count your squares before you commit to any one method.

The Most Popular Methods for Joining Granny Squares

There is no single correct way to join granny squares, and experienced crocheters often have strong preferences shaped by years of use. Here is an honest breakdown of the most popular methods so you can choose the one that suits your project and your style.

The Flat Slip Stitch Join

This is one of the most commonly used methods and creates a very clean, subtle seam on the right side of your work. You hold two squares with wrong sides together and use a slip stitch through both layers of corresponding corner and edge stitches.

The flat slip stitch join sits almost invisibly on the right side, especially if you use a matching color. It is neat, relatively fast, and produces a flexible seam that drapes well. For bags, this works nicely for the side panels, though the seam adds very little structure.

To do it: hold your two squares with wrong sides facing each other. Insert your hook through the back loop of the corresponding stitch on the first square and the back loop of the corresponding stitch on the second square at the same time. Yarn over and pull through. Continue to the end of the edge, then secure and weave in the end.

The Flat Single Crochet Join

This is similar to the slip stitch join but uses a single crochet stitch instead, which creates a slightly raised ridge on the wrong side of the work. Because you are working with wrong sides together, that ridge stays hidden inside the bag.

The flat single crochet join is a bit more substantial than the slip stitch join, making it a great choice for bags where you want a little extra durability at the seams. It is also a forgiving method if your squares are slightly different sizes, because the single crochet gives you a small amount of flexibility to ease stitches together.

The Woven Join (Mattress Stitch)

This join is done with a yarn needle rather than a crochet hook. You lay two squares flat, right sides up, and use a yarn needle threaded with matching yarn to weave through the stitches of both edges in a figure-eight or whip stitch motion.

The woven join creates an almost invisible seam on the right side and keeps the work very flat. It is the most invisible of all the joining methods, but it takes more time and can feel fiddly if your squares have a lot of corner chain spaces to navigate. For a bag, it works beautifully on the exterior panels if you want the joins to disappear entirely.

The Join As You Go Method (JAYG)

This is a technique where you attach each new square to the previous one during the final round of crocheting, rather than seaming finished squares together afterward. Instead of making a chain space at the corners and edges of your last round, you replace those chains with slip stitches into the corresponding space of the adjacent finished square.

Join as you go is a favorite among crocheters who want to avoid the finishing process because there are far fewer ends to weave in and no separate joining step. However, it requires more planning upfront because you need to work in a specific order, attaching each new square to the right edge of the right existing square.

For a bag, JAYG works wonderfully if you are comfortable working in a structured sequence. It produces a flat, tidy finish with joins that blend naturally into the look of the squares themselves.

The Visible Chain Space Join

This method intentionally creates visible join lines as a design feature. You hold two squares with right sides together and work a slip stitch or single crochet join from the wrong side, then turn the work out so the ridge shows on the right side. Alternatively, you join with right sides facing outward so the join ridge is deliberately raised and visible.

For a modern or graphic-looking bag, this can be a stunning design choice. Using a contrasting color for the join creates bold lines that look intentional and artistic.

How to Join Granny Squares Step by Step for a Bag

Now that you understand the options, here is a practical step-by-step guide using the flat single crochet join, which is probably the best all-around method for a crochet bag because it is durable, tidy, and not too fiddly.

Start by laying all your finished squares out on a flat surface in your planned arrangement. Take a photo so you can refer back to it.

Pin or clip your first two squares together with wrong sides facing. Make sure the edges line up neatly and corners match.

Join your yarn in the corner stitch of both squares at once by inserting your hook through both corresponding stitches, yarning over, and pulling up a loop.

Chain one, then work a single crochet into each pair of corresponding stitches along the edge, working through both layers together. At corner chain spaces, work a single crochet through both chain spaces at once.

When you reach the end of the edge, fasten off and weave in your end. Repeat until all squares in a row are joined, then join the rows to each other.

For the bag body, join squares into horizontal strips first, then join the strips together vertically. This makes the process more manageable and helps you keep your layout correct.

Once your front and back panels are complete, join them to the base panel, then join the front and back panels to each other at the sides. If you are making a gusseted bag, add the side strips here.

Tips for Professional-Looking Joins

A few small habits will make a significant difference in how polished your finished bag looks.

Always block your squares before joining them. Blocking means wetting them, gently squeezing out the excess water, and pinning them to a foam mat or blocking board at their exact intended size. This evens out any tension differences and makes your squares the same size, which makes joining so much easier.

Use stitch markers to mark the center stitch of each edge. This helps you match up the midpoints of your squares so any slight sizing differences get distributed evenly rather than bunching up at one end.

Keep your joining tension consistent. It is easy to pull too tightly when joining, which causes the seam to pucker and the fabric to pull inward. Practice on a small sample before you start your bag.

Weave in your ends as you go rather than saving them all for the end. Trust this advice. You will thank yourself later.

Adding Handles

Handles can be crocheted, or you can use purchased bag handles in wood, bamboo, or metal. For crocheted handles, a row of single or double crochet worked back and forth creates a sturdy strap. A braided cord of chain stitches is another quick option.

Attach handles by folding the top edge of the bag inward and securing it with slip stitches or a whip stitch, then attaching the handle ends to the reinforced top edge. For wooden ring handles, gather the top of the bag around the rings and stitch the fabric to itself through both layers to secure.

Lining Your Granny Square Bag

Lining is what turns a pretty crochet project into a truly functional everyday bag. It protects small items from slipping through the gaps between squares, keeps the bag from stretching out of shape, and adds a polished, professional finish when you peek inside.

To line your bag, cut two pieces of fabric (or one large piece if you are doing a simple rectangle) slightly larger than your bag’s interior. Use a cotton fabric, canvas, or a woven lining fabric. Sew the lining pieces together at the side and base seams, press the seams flat, fold the top edge down by about half an inch, and press. Slip the lining inside the finished bag, pin it to the top edge, and whip stitch it in place by hand using a matching thread.

If you want to add an interior pocket, sew a simple rectangular pocket to the lining piece before inserting it into the bag.

Free Template for Planning Your Granny Square Bag Layout

Print or trace this grid to plan your bag layout before you start joining. Each square in the grid represents one granny square. Shade in colors or mark your squares with letters to represent different color groups.

Front/Back Panel (adjust to your bag size):

Base Panel:

Side Gusset (optional, for a boxier bag):

Use this template to count how many squares you need in each color, check that your color distribution looks balanced, and plan which joining method you will use for which seams.

Final Thoughts

Joining granny squares is one of those skills that feels slightly intimidating the first time and then becomes almost meditative once you find your rhythm. There is a real pleasure in watching a loose collection of colorful squares transform into a cohesive, beautiful bag with every row of joining stitches.

The key is to choose a method that suits both your skill level and the look you want, to take the time to block your squares before you start, and to work through the joining in a logical order so your layout stays exactly as you planned it.

Whether you go with the barely-there mattress stitch, the satisfying snap of single crochet joins worked right sides together, or the seamless result of join as you go, your finished bag is going to be something you are genuinely proud to use or give as a gift.

Happy crocheting, and do not forget to save or print the free template before you get started.