A bag starts with yarn, needles, and a straightforward rectangle

A knitted bag is a rectangle you fold in half and seam up the sides. You cast on stitches for the width you want, knit rows until the piece is twice as tall as you need it to be, then bind off. Fold it in half lengthwise, seam the two long sides together with a tapestry needle, and you have a bag. The simplest bags use garter stitch (knit every row) or stockinette stitch (alternate knit and purl rows), both of which are beginner patterns.

The size depends on how many stitches you cast on and how many rows you knit. A small crossbody bag might be 30 stitches wide and 80 rows tall. A larger tote could be 50 stitches wide and 120 rows tall. Yarn weight matters too — thicker yarn creates a sturdier bag faster, while thinner yarn takes longer but gives you more control over the final shape.

Key Takeaways

  • A basic bag is a rectangle folded in half, so you cast on for width, knit to double your desired height, then seam the sides.
  • Garter stitch and stockinette stitch are the easiest patterns for bags and require no shaping or color changes.
  • Yarn weight determines how quickly you finish and how sturdy the bag feels — worsted weight is a good middle ground for beginners.
  • You will need a tapestry needle to seam the sides together after binding off, and blocking (wetting and shaping) makes the seams sit flat.
  • Adding handles requires either picking up stitches along the top edge or knitting a separate strip and sewing it on.

Choose yarn weight and needle size based on how sturdy you want the bag

Worsted weight yarn (also called medium or #4) is the standard choice for bags because it knits up fast, holds its shape, and is thick enough to support weight without sagging. Bulky yarn (#5 and up) finishes even faster but can look loose and floppy. Fingering or sport weight (#1 or #2) takes much longer and is better for small bags or detailed patterns.

Match your needle size to the yarn label. Most worsted weight calls for US 8 to 10 needles. Needles that are too small make the fabric tight and stiff; needles that are too large make it loose and stretchy. If you do not have the exact size, go one size up or down and knit a gauge swatch — a 4-inch square in your stitch pattern — to see if the fabric feels right for a bag.

Natural fibers like wool and wool blends are more durable than acrylic for bags because they hold their shape longer and resist pilling. If you plan to use the bag often, wool or a wool-acrylic blend is worth the extra cost.

Cast on and knit the body in one continuous piece

Cast on the number of stitches for your bag width using the long-tail cast-on or cable cast-on — both create a sturdy edge that will not unravel. For a medium bag, cast on 40 to 50 stitches. For a small bag, 25 to 35 stitches. For a large tote, 55 to 70 stitches.

Knit every row (garter stitch) or alternate knit and purl rows (stockinette stitch). Garter stitch is thicker and more textured; stockinette is smoother and drapes better. Both work equally well for bags. Keep knitting until your piece is roughly twice the height you want the finished bag to be — if you want a 10-inch-tall bag, knit until the piece is about 20 inches tall.

Count your rows as you go. Most bags take 80 to 150 rows depending on yarn weight and how tall you want them. Bind off loosely so the top edge does not pucker. Cut the yarn, pull it through the last loop, and weave the tail in with a tapestry needle.

Seam the sides and add handles

Lay the rectangle flat. Fold it in half lengthwise so the two short ends meet. Thread a tapestry needle with yarn that matches your bag (or use the tail you left at the bind-off). Using the mattress stitch, seam the two long sides together from the inside. The mattress stitch runs the needle under the bumps along the edge of each side, creating an invisible seam.

To work mattress stitch, insert the needle under the first bump on one side, then under the first bump on the other side, then back to the first side one bump up. Keep the tension loose enough that the seam does not pucker but tight enough that it does not gap. Seam all the way to the top, then weave in the tail.

For handles, pick up stitches along the top edge using a smaller needle and knit a strip 2 to 4 inches wide and 12 to 16 inches long (depending on how long you want the handles). Bind off and sew both ends to the inside of the bag. Alternatively, knit two separate strips and sew them on as handles after the bag is complete.

Block the finished bag to flatten seams and set the shape

Blocking is optional but makes a big difference in how polished the bag looks. Wet the finished bag in cool water with a drop of wool wash or gentle detergent, squeeze out the excess water gently, and lay it flat on a towel or blocking board. Shape it into a rectangle, smooth out the seams, and let it dry completely — usually 24 to 48 hours.

If you used acrylic yarn, you can also steam-block: hold a steamer or iron set to low heat a few inches above the bag without touching it directly. The heat sets the stitches and flattens the seams. Do not press down hard or you will crush the texture.

Common mistakes and how to avoid them

Casting on too tightly is the most common problem — it makes the bottom edge stiff and hard to seam. Use a larger needle for the cast-on row, then switch to your regular needle for the body. Binding off too tightly has the same effect on the top edge.

Seaming too tightly puckers the sides and makes the bag look bunched. Keep your seaming tension loose and even. If you pull too hard, the seam will show and the bag will not lie flat.

Choosing yarn that is too thin or too loosely spun makes the bag sag under weight. Worsted weight or heavier is safer for a first bag. If you want something lighter, use a sturdy blend like wool-acrylic rather than pure acrylic.

Forgetting to weave in ends before seaming means you have to do it after, which is harder. Weave in all tails as you go, especially the cast-on and bind-off tails.

Adding pockets, linings, or decorative details

Once you have made a basic bag, you can add features. Pockets are easiest: knit a small rectangle separately, block it, and sew it to the inside of the bag before seaming the sides. A 4-by-6-inch pocket is practical without being bulky.

A lining prevents items from snagging on the inside bumps of garter stitch. Cut a piece of cotton or linen fabric slightly smaller than your bag, fold the raw edges under, and sew it to the inside with a needle and thread. This also makes the bag feel more finished.

Decorative details like stripes, color changes, or a contrasting bind-off edge are straightforward once you understand the basics. Stripes are as straightforward as switching yarn colors every few rows. A contrasting bind-off means knitting the last row or two in a different color before binding off.

Frequently Asked Questions

How much yarn do I need for a bag?

A small bag uses 200 to 400 yards, a medium bag 400 to 800 yards, and a large tote 800 to 1200 yards. Check the yardage on the yarn label and buy one or two extra balls to be safe. It is easier to have leftover yarn than to run short and not be able to finish.

Can I knit a bag in the round instead of flat?

Yes, but it is more complex. You cast on in the round using circular needles or double-pointed needles, knit the body, then bind off. You still need handles, and you skip the seaming step. Flat knitting is simpler for beginners because you only have to manage one needle and one direction.

What if my bag is too loose or stretches out of shape?

Loose bags usually mean your tension is too loose or your needles are too large. Try going down a needle size or practicing tighter tension on your next bag. Blocking also helps — wet-blocking can tighten a loose bag slightly. If the bag is already finished and too loose, you can reinforce the seams by running a second line of stitching next to the first.

Do I need to add a lining?

No, but it makes the bag last longer and look more polished. A lining protects the inside from wear and prevents small items from catching on the knit bumps. For a first bag, skip the lining and add it later if you want to.

How do I make the bag waterproof?

Knitted bags are not waterproof on their own because yarn is porous. You can line the bag with waterproof fabric like oilcloth or laminated cotton, or spray the finished bag with a fabric water-repellent product. Neither method is perfect, so do not rely on a knitted bag to protect electronics or documents in heavy rain.