How the binding math works
- Find the length. Perimeter = 2 × (width + length). Add about 12" for mitered corners and joining the ends.
- Count the strips. Each strip cut across the width of fabric gives you about 40" of length. Every join uses some of it: roughly one strip width for a diagonal join, ½" for a straight one. Round up to whole strips.
- Convert to yardage. Strips × strip width gives the inches of fabric you cut through. Divide by 36 and round up to the next ⅛ yard.
Example: a 60" × 80" quilt has a 280" perimeter, so you need 292" with the 12" allowance. With 40" usable fabric and diagonal joins, each additional strip adds 37½", so you need 8 strips. 8 × 2½" = 20" of fabric, which rounds up to ⅝ yard.
Binding yardage chart
2½" strips, 40" usable fabric width, diagonal joins and 12" extra.
| Quilt | Size | Strips | Fabric |
|---|---|---|---|
| Mini | 24" × 24" | 3 | ¼ yd |
| Baby | 36" × 52" | 5 | ⅜ yd |
| Throw | 60" × 70" | 8 | ⅝ yd |
| Twin | 70" × 90" | 9 | ⅝ yd |
| Queen | 90" × 100" | 11 | ⅞ yd |
| King | 108" × 100" | 12 | ⅞ yd |
Binding tips
- Press the joined strip in half lengthwise, wrong sides together, before you sew it on. That's double-fold binding.
- Start sewing partway down one side, not at a corner, and leave an 8–10" tail so you have room to join the ends.
- Cutting from fat quarters? A fat quarter is about 18" × 21", so each strip is only about 20" long. You'll need roughly twice as many strips, and twice as many joins, as the calculator shows for full-width fabric.
- Planning the whole quilt? Work out the back with the backing calculator.