How to Calculate Piping Cord and Fabric Yardage

Piping needs two different quantities: the cord length that follows the project perimeter and the fabric strip length needed to cover that cord. Treating those as the same measurement is the fastest way to run short. Start with the finished seam path, add a deliberate join overlap, then convert the chosen strip width into a cut plan.

Measure each edge that receives piping. Add the edges rather than estimating from the cushion’s area. If the piping turns around a corner, the corner does not add a full extra length, but the seam construction may need a little extra cord at the start and finish. Record that join allowance explicitly.

Find cord length and strip width

Let the total seam path be P. Add a join allowance J and any tail allowance T: cut cord length = P + J + T. For a square cushion with a 20-inch finished face and piping on both faces, the path is 4 × 20 × 2 = 160 inches before the join. If you plan a 2-inch overlap and two 3-inch tails, the cut cord length is 168 inches.

The strip width depends on cord diameter and seam allowance. A 5/32-inch cord with a 1-inch seam allowance on each side needs at least 2 × (1 + 5/32) inches before any cutting margin. Round the strip width to the width your cutting method can repeat. Bias strips handle curves more gracefully; straight-grain strips may be efficient for square corners and stable edges.

Worked example

Suppose four 20-inch cushion edges are piped on the top and bottom, with 2 inches for joining and 6 inches of total tail allowance. The perimeter is 4 × 20 = 80 inches; both faces require 160 inches. Add the join and tails: 160 + 2 + 6 = 168 inches, or 4.667 yards of continuous strip length.

If the usable fabric width is 42 inches and your finished strip width is 2.5 inches, 16 strips fit across one width because floor(42 ÷ 2.5) = 16. Sixteen strips from one 2.5-inch-wide crosscut span 40 inches of strip length, so five crosscuts provide 200 inches before edge loss. If the print direction requires lengthwise strips, this width packing is not legal; switch to the lengthwise plan and re-run the arithmetic.

Verification checklist

• Measure the finished seam path, not the cushion’s diagonal or area.
• Count every face or edge that receives piping.
• Add one explicit join allowance and tail allowance.
• Record cord diameter and both seam allowances.
• Choose bias or straight grain based on the curve and fabric direction.
• Check whether the strip may rotate on the fabric.
• Round up to the shop increment and keep a spare strip for testing.

Caution

Piping can consume more fabric than its area suggests because strips must follow a legal grain and may need matching. The calculator is a planning aid, not a substitute for laying strips on the actual fabric. Follow the pattern or upholstery instructions when they specify a different cord size or seam allowance.

Sources and derivation

Use the seam and hem allowance reference for allowance terminology and the cushion cover calculator for the perimeter check. Compare the join-loss boundary with continuous bias binding yardage before cutting a long run.