How to calculate quilt binding
Add up the four sides of the quilt and add about 12″ for the corners and joining the ends. Divide by the usable width of your fabric (40″) and round up to whole strips, then multiply the strips by their width. A 62 × 76″ throw needs 276″ + 12″ = 288″: eight 2½″ strips, 20″ of fabric, ⅝ yd.
Plan it in your own fabrics with Sashing →
Step 1: the perimeter
Perimeter = 2 × width + 2 × length of the finished quilt, borders included. For a 62 × 76″ throw: 2 × 62 + 2 × 76 = 276″.
Step 2: add for the corners and the join
Binding folds at each mitred corner and needs tails to join its two ends. Sources suggest adding 10″ to 12″. Sashing adds 12″, which gives a comfortable tail at each end: 276 + 12 = 288″.
Step 3: how many strips
Binding is cut in strips across the width of fabric, then joined end to end. Each join uses about ½″, so divide by the usable width less ½″ and round up:
(288 − ½) ÷ (40 − ½) = 7.3, so 8 strips, joined with 7 seams.
Why 40″ and not the 42–44″ on the bolt? The selvages come off and prewashing shrinks the fabric, and a binding one strip short can only be fixed with fabric you may no longer have. In a cutting chart this reads “(8) 2½″ × WOF, join end to end (7 seams): binding”. See how to read a quilt cutting chart.
Step 4: yardage
8 strips × 2½″ = 20″. Divide by 36 and round up to the next ⅛ yd: 0.56, so ⅝ yd. If the binding shares a fabric with the border, add their inches before rounding. Rounding each separately and adding can cost you an extra ⅛. The border guide works the same throw's border.
Binding for common quilt sizes
At 2½″ strips and 40″ usable width, for the quilts in the quilt sizes chart:
| Quilt | Binding length | Strips | Buy |
|---|---|---|---|
| 34 × 48″ | 176″ | 5 | ⅜ yd |
| 62 × 76″ | 288″ | 8 | ⅝ yd |
| 76 × 90″ | 344″ | 9 | ⅝ yd |
| 90 × 104″ | 400″ | 11 | ⅞ yd |
| 104 × 104″ | 428″ | 11 | ⅞ yd |
How wide to cut binding strips
2½″ strips, folded in half lengthwise, make a double-fold binding about ⅜″ to ½″ wide on the front, depending on the batting. It is the most common width, and the one Sashing plans. Many quilters prefer 2¼″ for a narrower edge on a thin batting. Use the same method with your width: the strip count stays the same, and only the yardage changes.
Bias binding, for curved or scalloped edges, is cut on the diagonal from a square and needs a different calculation, which Sashing does not do. Straight edges, which every quilt in the app has, only need straight-grain strips.
The backing is the other fabric that sits outside the quilt top: how much fabric for quilt backing.
Sashing
A quilt design app for Android. Lay out classic blocks with sashing and borders in photos of your own fabrics, then get the finished size, the yardage for every fabric and a cutting chart with the ¼″ seams added. Designing and seeing the quilt is free; the yardage, cutting chart and PDF are part of Sashing Pro, a subscription with a 3-day free trial.