How to make a foldable shopping bag

1. Materials & tools

Materials (standard size)

• Main fabric (lightweight nylon or fine cotton) — about 110 cm wide × 90 cm (44 × 35 in)
• Fabric for the fold-away pocket — about 15 × 20 cm (6 × 8 in)
• Optional: a snap or short elastic to hold it folded

Tools

• Sewing machine (or needle and thread)
• Fabric marker or pencil
• Ruler and scissors
• Iron
• Pins or clips

2. Make the pattern (auto-generated in Katagami)

With the Katagami pattern tool, you just enter the finished size and it drafts a seam-allowance-included pattern, tiled to print at actual size on Letter or A4.

1. Open the tool
   Open the pattern tool and choose “Bags” → “Foldable shopping bag” from the tabs at the top.
2. Enter the size
   Enter the finished width, height, gusset and handle length. Presets cover small, standard and large.
3. Set the seam allowance
   Use the slider at the bottom (beginners: 1.0–1.5 cm / about 3/8–5/8 in).
4. Print
   Press “Print (actual size)”, then in the print dialog set Scale = 100% and turn “Fit to page” OFF. Check the 50 mm calibration box on the first guide sheet with a ruler.

3. Cutting the fabric

1. Trace the pattern
   Trace the body (base on the fold), the handles and the pocket.
2. Cut
   Cut one body, two handles and one pocket.
3. Finish the edges
   Serge or zigzag, or use French seams — lightweight nylon frays quickly.

4. Sewing

4-1. Make the handles and pocket

1. Fold each handle in quarters lengthwise and topstitch both long edges.
2. Turn the pocket's opening edge under twice and stitch, then press the other three edges under.

4-2. Attach the pocket

1. Topstitch the pocket to the outside of the body, low on one side, while the fabric is still flat.
2. This is the pocket the whole bag folds into, so stitch all three edges firmly.

4-3. Sew the body

1. Fold the body at the base, right sides together, and sew both sides.
2. Pinch each base corner into a triangle and sew across to form the gusset.

4-4. Finish the opening and handles

1. Turn the opening edge under twice and stitch.
2. Topstitch the handles to the inside of the opening with a stitched rectangle and a cross at each end.
3. Lightweight fabric plus a full shopping bag is a lot of load on four small squares of stitching, so go over them twice.

✏️ Reinforce the handle attachments harder than feels necessary. Thin nylon tears at the stitch line long before the fabric itself gives way, and a bag of groceries finds that point immediately.

5. Tips & variations

• French seams: they enclose every raw edge, which makes a thin bag far more durable.
• Fold it small: roll from the base and tuck it into its pocket. A snap keeps it closed.
• Ripstop: ripstop nylon is light, strong and packs down to almost nothing.