How to make a foldable shopping bag

1. Materials & tools

Materials (standard size)

• Main fabric (lightweight nylon or fine cotton) — about 110 cm wide × 100 cm (43 × 39 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
   Place the lower edge (the base) of the pattern on the fabric fold and trace the cutting and stitching lines.
2. Cut
   Cut one body (base on the fold) and two handles.
3. Finish the edges
   Serge or zigzag, or use French seams — lightweight nylon frays quickly.

4. Sewing

4-1. Make the handles

1. Fold each handle in quarters lengthwise and topstitch both long edges. Make two.

4-2. 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 on the gusset line. Trim the point to 1 cm or leave it folded flat.

4-3. Finish the opening and handles

1. Turn the opening edge under by the allowance, then again, to make a double-fold hem.
2. Tuck the handle ends inside the opening and baste them, measuring from the center so both sides match.
3. Stitch all around the opening, catching the handles. Fold the handles up and stitch again for strength — a stitched rectangle with a cross at each end.

✏️ 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 it up from the base. An elastic loop or a snap on one handle keeps the roll closed.
• Ripstop: ripstop nylon is light, strong and packs down to almost nothing.