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This bag with box bottom corners came about by special request of my daughter, who had been using a bag she liked as her pencil bag but it wasn’t quite perfect. I hope I’ve gotten closer with this one!
The Original Bag
I think this bag originally held a set of sheets. It’s made from two pieces of fabric with a box bottom and a flap and Velcro closure at the top.
She didn’t love the Velcro because it got fuzzy and was shedding in her bag. The bag also developed a hole in the bottom and a few highlighter stains.
But she loves the size and style of this bag so it was time for a new and improved knockoff.
Supplies for a Bag with Box Bottom Corners
This is a pretty easy sewing pattern and doesn’t require a lot of supplies. You’ll need two pieces of fabric of your desired size. The original bag was about 12 inches/30.5 cm square, so I cut my pieces to be 14 inches/35.5 cm square to account for seam allowances and cutting the corners for the box bottom.
You’ll also need thread to coordinate and a sewing machine, plus a zipper at least as wide as your fabric. I ended up cutting down a 24-inch/61 cm zipper because that’s the one I had in the house that was the right color.
Some Wonder Clips or pins will be helpful, and you’ll also need fabric scissors. I also used pinking shears, but that’s optional. A ruler and a marking tool like a heat erasable pen is good for marking the corners. If you need to cut your fabric, a rotary cutter and mat would be helpful.
Sewing a Box Bottom Bag
Place your fabric right-sides together and clip or pin together along three sides.
Sew along those sides with your preferred seam allowance.
Use pinking shears to trim the seam allowance, or zig-zag the edges.
Install the zipper on the open side of the bag. Begin by clipping or pinning one side of the zipper (while open) to one side of the fabric, situated such that the top/front/right side of the zipper is touching the right/front side of the bag and that the other side of the zipper will align with the other side of the bag.
With the zipper still open and using the zipper foot on your sewing machine, sew the zipper and the bag together. You’ll want to get close to the teeth. As you sew, stop and zip the zipper closed so that you don’t have to stitch around the zipper pull.
Repeat on the other side. Fold over and sew down the flaps at the top of the zipper.
Zip the bag closed and make sure the zipper is secure where you want it and fully sewn down. I went back and sewed a bit closer on that part where you can see it’s uneven.
Switch back to your regular foot and zigzag along the edge of the zipper and the raw edge of the fabric to prevent fraying.
Adding the Box Bottom
Of course to make this a bag with box bottom corners, we need to do a little more to the bottom of the bag. With the wrong/inside of the bag facing out, mark a square of 2 inches/5 cm at each bottom corner.
Cut this fabric away.
Fold the bottom of the bag so that the side and bottom seams are aligned and the corner you just cut is flat on either side of the seams (it’s easier to see in the picture than to say in words).
Sew this seam.
Repeat on the other side. Pink or zigzag the seams.
On the outside this makes the base flat and gives it a boxy look, but it’s still only two pieces of fabric. Isn’t that clever?
So far the girl seems to really like her bag with box bottom corners that has a lot more personality and hopefully is a little more durable than the original. Now I just need to learn how to get highlighter out of fabric!
