How to calculate fabric for quilt borders

30 September 2026 · Sashing guides

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Step 1: measure the quilt centre

Measure the pieced centre across the middle as well as at the edges, and use the middle figure: edges stretch while you piece. For the worked example the centre is twenty 12″ blocks with 2″ sashing, 54 × 68″ (see how sashing sets the size).

Step 2: add up the length of border you need

With butted corners the side borders go on first and the top and bottom borders run across them:

• Sides: 2 × (centre length + ½″) = 2 × 68½″ = 137″
• Top and bottom: 2 × (centre width + 2 × border + ½″) = 2 × (54 + 8 + ½)″ = 125″
• Total: 262″ of 4″ border

The ½″ on each piece is the seam allowance where the border meets the next border or the binding at each end. That is how Sashing adds up a border. Some patterns skip it and add a safety margin instead.

Step 3: how many strips across the fabric

Borders are usually cut across the width of fabric (WOF) and joined end to end. Divide the total by the usable width and round up. Quilting cotton is sold 42–44″ wide, but after the selvages come off and after prewashing, 40″ is what you can count on. Each join also uses ½″ of length. So the count is the smallest number of strips whose length, less the joins, reaches 262″:

(262 − ½) ÷ (40 − ½) = 6.6, so 7 strips, joined with 6 seams.

Cut each strip the border width plus ½″, so 4½″ here. In a cutting chart the line reads “(7) 4½″ × WOF, join end to end (6 seams): border”; how to read a cutting chart explains the notation.

Step 4: turn strips into yardage

7 strips × 4½″ = 31½″ of fabric. Divide by 36: 0.875, exactly ⅞ yd. Round anything else up to the next ⅛ yd, with ¼ yd as the smallest amount Sashing lists. In centimetres, 31½″ is 80.01 cm, and rounding up to the next 10 cm gives 90 cm.

If the same fabric is also your binding, add its strips before you round: eight 2½″ binding strips add 20″, so 51½″ in all, and 1½ yd. See how to calculate quilt binding.

A second border

Work outward: the second border is measured on the quilt with the first one on. After a 4″ border the quilt is 62 × 76″, so a 6″ outer border needs 2 × 76½″ + 2 × (62 + 12 + ½)″ = 153 + 149 = 302″. That is 8 strips of 6½″, 52″ of fabric, rounded up to 1½ yd.

When your numbers will differ

• Mitred corners need each strip to run past the corner by the border width, so they take more than butted corners.
• Borders cut along the length of the fabric have no joins but need yardage as long as the quilt. That is worth it for a large print, and wasteful for a solid.
• A 42″ width sometimes saves a strip: 262″ still needs 7 strips at 42″, but a slightly shorter border might need one fewer.