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Pencil Pleat Calculator — Tape & Fabric
Calculate fabric and tape for pencil pleat curtain headings.
How We Calculate This
Pencil pleat curtains use heading tape that draws up into even, closely packed folds. Fabric quantity depends on fullness ratio and the heading tape width determines the heading allowance.
The formula
Total width = Track width × Fullness ratio
Usable width = Fabric width − 2 × Selvedge trim
Widths per curtain = ceil((Total width ÷ Curtains) ÷ Usable width)
Fabric widths = Widths per curtain × Curtains
Heading allowance = Tape width + 3cm
Cut drop = Drop + Hem + Heading allowance
Tape = Fabric widths × Fabric width + ~10cm per curtain (≈20cm for a pair)
Selvedges are trimmed before the widths are joined, so the usable gathering width per width is the fabric width minus twice the selvedge trim. For patterned fabric each cut drop is rounded up to a whole pattern repeat and one extra repeat is added to the total so the design can be matched across joined widths.
Frequently Asked Questions
Standard pencil pleat uses 2-2.5x fullness. The tape manufacturer usually specifies the correct ratio. 2.25x is the most common. Using less looks skimpy; using more wastes fabric and makes curtains bulky.
Standard pencil pleat tape is 7.5cm (3in) wide with 3 hook pockets. Deep pencil pleat tape is 15cm (6in) for a more luxurious heading. Narrow tape (3cm) is used for lightweight curtains and valances.
Allow the tape width plus 3cm for folding the fabric over the tape. For 7.5cm tape, allow 10.5cm. The fabric folds over the top of the tape and is stitched along the bottom, enclosing the tape.
You need tape equal to the total ungathered curtain width plus about 10cm per curtain for turning under at each end. For a standard pair that is roughly 20cm extra. The ungathered width equals the number of fabric widths times the fabric width. Allow more if joining tape lengths.
Yes. Each cut drop is rounded up to a whole pattern repeat so every width starts at the same point in the design, and one additional pattern repeat is added to the order so you can choose where the pattern sits and match it across joined widths (Sew-Helpful Step 3). Plain fabric needs no repeat allowance.
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Last updated: February 2026
All calculations are estimates. Always verify quantities before cutting or purchasing fabric.