Bias Tape Length Calculator
Figures out exactly how much bias tape or binding you need to finish the edges of any fabric project. Accounts for perimeter length, corner mitering, and a working buffer so you never run short.
About this calculator
Bias tape is used to encase raw fabric edges on quilts, garments, and crafts. The total length required is the sum of three components: the perimeter of the area being bound, extra length consumed at each corner for mitering or folding, and a general extra allowance for joining, starting, and finishing ends. The formula is: total length = perimeterLength + (corners × 2) + extraAllowance. The corners term adds 2 inches per corner — a common allowance for a mitered or folded corner. The extraAllowance field lets you add a project-specific buffer (typically 6–12 inches) for overlap at the join and any fitting adjustments. Bias tape is cut on the 45° grain of the fabric, which gives it stretch and allows it to curve smoothly around edges and corners without puckering.
How to use
You are binding a baby quilt with a perimeter of 180 inches (e.g., 45" × 45" quilt: 4 × 45 = 180"). It has 4 corners, and you want 10 inches of extra allowance. Step 1 — corner allowance: 4 × 2 = 8 inches. Step 2 — add all components: 180 + 8 + 10 = 198 inches total. Step 3 — convert to yards if needed: 198 / 36 ≈ 5.5 yards of bias tape. Purchase at least 5.5 yards, or round up to 6 yards for peace of mind.
Frequently asked questions
How much extra bias tape should I add for joining and finishing the ends?
Most sewists recommend adding at least 6 to 12 inches beyond the calculated perimeter-plus-corners total. This extra length covers the diagonal join where the two ends of the binding meet, plus any small adjustments needed when easing the tape around curves or corners. For quilts larger than a lap size, bumping that buffer to 15–18 inches is a safe practice. It is always easier to trim excess than to piece in a short length.
Why is bias tape cut on the diagonal grain of the fabric?
Cutting strips at a 45° angle to the fabric's selvage places them on the true bias, where woven fabric has its maximum stretch. This stretch allows bias tape to curve smoothly around rounded edges and corners without forming tucks or puckers. Straight-grain tape can be used on perfectly straight edges, but it will pucker or distort on any curve. The bias cut also distributes wear more evenly along the edge over the life of the item.
What width of bias tape do I need for different types of projects?
Standard packaged bias tape comes in 1/2" (single fold) and 1" (double fold) widths. Double-fold 1/2" tape is typical for light garments and quilt binding on thin fabrics. Wider 1" or custom-cut double-fold tape — often 2.5" strips that finish to about 1/2" — is preferred for quilts because it is more durable and easier to hand-stitch to the back. For heavy upholstery or bag edges, cut even wider strips (3"–4") to achieve a sturdy, visible binding.