How many curtain hooks per metre, and how much fabric?

These are the rules behind the Curtain Calculator. Every number of hooks and every metre of fabric on this page is worked out by that calculator. It's an estimate to plan with, not a quote.

How the number of hooks is worked out

The calculator takes 24mm off the track width, divides what is left by the number of fabric pieces and then by the runner spacing, and adds one hook. For Wave Fold and S Fold the answer is rounded up to an even number. For pleated curtains it is rounded up to a whole number.

The first three columns are Wave Fold and S Fold, which need the same number of hooks. A curtain in more than one piece is worked out for each piece: a 3600mm track in two pieces on 60mm runners is 32 x 2.

Hook spacing: runner spacing and tape spacing

Runner spacing is the distance between each runner, or glider, in the track. The calculator offers 48, 54 and 60mm for Wave Fold and S Fold, and 100mm for pleated headings.

For Wave Fold and S Fold, the runner spacing and the tape spacing together set the fullness: how much fabric the curtain takes for its width. The calculator takes Wave Fold tape spacings of 95, 108, 120, 140 and 160mm.

The table is metres of fabric for each metre of track. Wave Fold on 54mm and 60mm runners is worked out at the same fullness. In the calculator, S Fold takes 108mm tape: 2.7m on 48mm runners, 2.4m on 54mm runners, 2.1m on 60mm runners. Pinch pleat, box pleat and goblet pleat curtains are worked out at 2.5 times fullness, and pencil pleat can be set from 1.5 to 3 times.

How much fabric: with a join or without

First the calculator checks whether the drop fits across the roll. It adds a top hem allowance and the bottom hem allowance to the drop, and compares that with the fabric width less 40mm. The top hem allowance is 25mm for Wave Fold, S Fold and pencil pleat, and 125mm for the other pleats.

Fabric Join NO means it fits. The fabric's width is used as the drop and the curtain is made in one continuous length, with no joins. Fabric Required is the track width in metres, rounded up to the next 0.1, times the fullness, rounded up again to the next 0.1m. Now and then the calculator lands 0.1m above the same sum done by hand. Go with the calculator.

Fabric Join YES means it doesn't fit. The fabric is turned 90 degrees and the widths are joined side by side, with vertical joins. The calculator multiplies the track width by the fullness and divides by the fabric width to count the widths, rounded up to whole widths (an overhang of up to 4% of one width doesn't add another). Each width takes one drop plus the top and bottom hem allowances.

Three worked examples

Example 1 is a Wave Fold curtain in one piece. The 2400mm drop fits across the 300cm fabric, so there is no join, and at 2.7m of fabric for each metre of track a 3600mm track needs 9.8m.

Example 2 is an S Fold curtain in two pieces, so the answer is 40 x 2: the hooks for each piece, and the number of pieces. A 2700mm drop doesn't fit across a 140cm fabric, so the fabric is joined in widths and the job needs 23.4m.

Example 3 is a Triple Pinch Pleat curtain in two pieces at 2.5 times fullness, also joined in widths: 13 x 2 hooks and 13.4m of fabric.

What the calculator takes, and what it leaves out

• Track width from 300 to 12000mm. A number under 300 is read as hooks for each piece instead, and the fabric is worked back from it.
• Fabric width from 138 to 420cm.
• Any drop is worked out. Drops of 1000 to 6200mm are covered by our Made to Spec Guarantee, and the calculator says so when a drop is outside that.
• One curtain panel is made up to 6.0m track width or 15.0m fabric width, whichever uses less fabric, so ask us about anything wider before you quote it.
• Fabric Required has no allowance for a pattern repeat.

Buying curtains for your own home? We only make for retailers, so get in touch and we'll point you to one near you.