How to Use Fabric Calculator
The Fabric Calculator is for sewists who need a quick estimate of how much fabric to purchase.
- Enter Finished Width and Length — The dimensions of the finished panel, garment piece, or quilt block.
- Enter Seam Allowance — Default is 1.5 cm / 5/8 in.
- Enter Bolt Width — Fabric store bolt width (cm or inches).
- Read the Result — The Fabric Calculator returns the total fabric width including seam allowance, total length needed, and total yardage / meterage to buy.
Formula & Theory — Fabric Calculator
total_width = finished_width + 2 × seam_allowance
total_length = finished_length + 2 × seam_allowance
panels = ceil(total_width ÷ bolt_width)
bolt_length = panels × total_length
area = total_width × total_length| Symbol | Meaning |
|---|---|
| finished_width | Width of finished panel |
| finished_length | Length of finished panel |
| seam_allowance | Allowance added to each edge |
| bolt_width | Fabric store bolt width |
| panels | Number of bolt-width panels needed |
Why the 2× Allowance?
A seam allowance is added on both edges (top + bottom, left + right). For a panel that needs to be hemmed only once, halve the calculation accordingly.
Use Cases for Fabric Calculator
- Dressmaking — Compute fabric for tops, dresses, and skirts.
- Quilting — Estimate background or border fabric.
- Home Décor — Pillow covers, tablecloths, slipcovers.
- Bag Making — Plan exterior, lining, and pocket fabric in one go.
- Costume & Cosplay — Bulk projects can use the Fabric Calculator to plan multiple panels.
The Fabric Calculator quickly turns finished dimensions into a clear shopping list.