How to Sew a Tote Bag with Flat Bottom

Large Flat Bottom Tote Bag

A large flat bottom tote uses the same rule as the small bag: finished base depth equals twice the corner cutout. The large row in the cutting matrix is two exterior panels at 20″ × 18″, a 3″ × 3″ corner notch, and a finished bag of 14″ wide × 15″ high × 6″ base. That height holds a paperback upright, which is the bookshelf tote people look for. It is this large cut, not a second pattern. More bags and sleeves are on the sewing projects hub, including the patchwork laptop sleeve when the tote is carrying a computer.

✨ AI Visual

Method 1: The Cutout Corner Method (Most Accurate Base)

The cutout corner method produces the crispest, most uniform flat base for canvas and quilting cotton tote bags:

1. Cut the Corner Squares: Layer your exterior panels right sides together. Using an acrylic ruler and a sharp 45mm rotary cutter, cut a 2-inch by 2-inch square from both bottom corners (do NOT cut the top corners). Repeat for the lining panels.
2. Stitch Side & Bottom Seams: Stitch the side seams and bottom seam with a 3/8-inch seam allowance, leaving the cut-out corner notches open.
3. Box the Corner: Pinch the corner open so the side seam aligns directly with the bottom seam. Press the seam allowances open (or nest them to opposite sides), pin securely, and stitch straight across with a reinforced 3/8-inch seam.

Method 2: The Pinch and Stitch Triangle Method

If you prefer not to cut your fabric beforehand, sew the side and bottom seams as a standard pouch, flatten the bottom corner into a triangle with the side seam centered, draw a 4-inch line perpendicular to the seam with an acrylic ruler, stitch across, and trim away the excess triangle.

Interfacing Selection: Achieving Structural Free-Standing Rigidity

The difference between a floppy bag that collapses into a pile and a crisp, freestanding market tote lies in your choice of stabilizer. Pellon SF101 Shape-Flex is a 100% cotton woven fusible, 20 inches wide, made for light-to-medium wovens (Pellon SF101; SF101 instruction PDF). One bolt width covers a 20-inch exterior panel. Pre-shrink it in warm water and let it dry before fusing, which is the maker’s own instruction, so the adhesive is not loosened in a washer. Cut the corner notches with a 45mm rotary cutter.

• Pellon SF101 Shape-Flex (All-Cotton Woven): Adds crispness and body while preserving the soft, breathable hand of cotton prints. Best for lightweight grocery and day totes.
• Pellon 987F Fusible Fleece (Low-Loft Polyester): Fuses to the exterior panels to add plush structure and protect delicate electronics (like a tablet or notebook) from ground impacts.
• Decovil Light (Non-Woven Leather-Like): Delivers rigid, professional designer bag stiffness without creasing when folded.

Interior Drop-In Slip Pocket Construction & Math

To add an organized phone and keys pocket inside your lining:

1. Cut a fabric rectangle measuring 9.0″ wide by 12.0″ tall.
2. Fold in half with right sides facing (creating a 9.0″ × 6.0″ rectangle). Stitch around the three open edges with a 1/4″ seam, leaving a 2-inch opening at the bottom.
3. Turn right side out through the opening, press edges crisp, and topstitch the top folded edge with a 1/8″ seam.
4. Center the pocket on one interior lining panel, 3.0 inches below the top raw edge. Edge-stitch the left, bottom, and right sides to secure, adding backstitches at top stress corners.

Attaching Reinforced Cotton Webbing Handles & Topstitching

Cut two 28-inch lengths of 1-inch cotton or nylon webbing. Position strap ends 3.5 inches inward from the side seams on the exterior panels. Stitch an "X-Box" reinforcement pattern (a 1-inch square with an stitched X inside) at the top hem to ensure the handles can easily carry 25+ lbs of heavy groceries, books, and laptops without tearing.

Finish the top opening by pressing the lining inward and edgestitching at 1/8″ followed by a parallel topstitch row at 3/8″ using a #90/14 Jeans needle and 3.0mm stitch length for clean industrial tension.