How to make a backpack

1. Materials & tools

Materials (standard size)

• Main fabric (canvas or nylon) — about 110 cm wide × 120 cm (44 × 47 in)
• Lining fabric — the same amount
• Heavy fusible interfacing — for the body
• Webbing for the straps (about 4 cm / 1½ in wide) — the length you chose
• Sliders and a buckle, or hook-and-loop — 1 set

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” → “Backpack” from the tabs at the top.
2. Enter the size
   Enter the finished width, height, gusset, strap length and width, and the flap depth. 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 panels, the gusset, the flap and the straps.
2. Cut
   Cut everything in main and lining, plus two straps. The gusset is long — take it along the length of the fabric.
3. Apply interfacing
   Fuse heavy interfacing to the main body and gusset.

4. Sewing

4-1. Make the straps and flap

1. Fold self-fabric straps in quarters and topstitch, or cut webbing to length and seal the ends.
2. Sew the flap in main and lining, leaving the attachment edge open. Turn, press and topstitch.

4-2. Attach the straps to the back panel

1. Stitch the strap tops to the back panel near the top, and the strap bottoms near the base.
2. Stitch each anchor as a rectangle with a cross through it, twice.
3. The straps carry everything the bag holds, so this is the joint that decides whether the bag survives.

4-3. Attach the gusset

1. Match the center of the gusset to the center of the base of one body panel and pin outward from there.
2. Sew all the way around, clipping the gusset allowance at the base corners.
3. Attach the second body panel the same way. Assemble the lining likewise, leaving a gap.

4-4. Join and close

1. Turn the main bag out and slip it inside the lining, right sides together, catching the flap at the back edge.
2. Sew around the opening, turn through the gap, close it and push the lining in.
3. Topstitch around the opening and fit the buckle or hook-and-loop.

✏️ Work outward from the center when attaching the gusset. Starting at one end guarantees the two pieces run out of step and the last corner will not close.

5. Tips & variations

• Webbing straps: stronger than self-fabric and far quicker. Add a shoulder pad if you carry weight.
• Base reinforcement: a second layer of fabric on the base is worth the ten minutes.
• Inner pocket: sew it to the lining while everything is still flat.