Pelmet Calculator — Fabric & Board Dimensions

As a rule of thumb a pelmet sits at roughly 1/5 to 1/6 of the finished curtain drop, so 35–42cm for a 210cm drop. Aim for at least 25–30cm so the fabric covers the curtain track and heading tape. This calculator accepts depths from 15cm (for very short windows) up to 60cm, but most pelmets on standard windows look best at 25cm or more. Shaped pelmets can be deeper at the centre.

The pelmet board should extend 10–15cm beyond each side of the curtain track so the drawn-back curtains tuck behind it. The return (the depth from the wall, set with the Return Depth input) needs to clear the curtain stack — typically 12–18cm, with 15cm a safe default.

A padded pelmet is soft, with wadding behind the fabric for a plump look. A buckram pelmet uses stiffened pelmet buckram for a rigid, structured shape and can be cut into a decorative shaped lower edge. Both wrap a face and a backing, so this calculator allows twice the depth plus turnings for the fabric height.

A pelmet piece is wide (board length plus returns) but not very tall. With plain furnishing fabric the piece is usually "railroaded" — cut sideways along the length of the bolt — so you buy the piece WIDTH in metres. With patterned or directional fabric the pattern must run upright, so the piece is made from joined drops cut across the standard 137cm bolt; you then buy drops × the cut drop. Turn on "Patterned / directional fabric" to switch the calculation to joined drops.

Yes, a pelmet board is essential. Use 15–18mm MDF or plywood. The board mounts above the window on angle brackets, and the pelmet fabric attaches to the board with hook-and-loop (Velcro) tape for easy removal and cleaning.