👜 Bag Calculator
Enter your bag’s dimensions to estimate how much fabric you’ll need and the bag’s interior volume.
Planning a bag sewing project
Before cutting fabric for a tote, purse, or pouch, it helps to know both how much material to buy and how much the finished bag will actually hold.
The formula
This calculator treats your bag as a rectangular box, computing total surface area with Surface Area = 2(L×H) + 2(W×H) + 2(L×W) for panels, then estimates fabric yardage by adding your seam allowance to each panel and dividing the total area by a standard 44-inch-wide fabric bolt (36 in × 44 in per yard). Interior volume uses Volume = Length × Width × Height, converted to liters.
This is a simplified box estimate — gussets, curved bottoms, linings, pockets, and straps will change actual yardage needs, so buy a bit extra fabric as a buffer. For general sewing planning purposes.