Fabric is ordered as a length of metres cut from the roll. The fabric quantity calculation depends on whether the fabric is PLAIN or has a PATTERN.

To calculate the fabric quantity you need the following

• Number of Fabric widths (calculated in STEP 2)
• Finished Curtain Length
• Vertical Pattern Repeat (if using patterned fabric)
• Hem allowance (20cm for full length curtains (double 10cm), 16cm for sill length (double 8cm))
• Heading allowance ( Buckram Depth + 5cm )

Plain Fabric cut drops are cut to the following size.

FABRIC QUANTITY REQUIRED (Plain Fabric)

The minimum PLAIN FABRIC required to make a pair of curtains is

FABRIC CUT DROP x NUMBER OF WIDTHS = PLAIN FABRIC QTY

PRO TIP: In the workroom we also add a 5cm trimming allowance to each cut drop for PLAIN FABRIC to enable us to straighten the ends of the cut lengths. We don't for PATTERN FABRIC as there is usually extra fabric in the ADJUSTED CUT DROP.

PATTERNED FABRIC

This tutorial is based on a standard pattern repeat fabric, if your fabric has a half drop pattern repeat please read HERE and adjust the instructions accordingly.

Note: The majority of fabrics are standard pattern repeat - check with your supplier.

When the fabric has a pattern we need to make sure

1. The pattern matches when we join drops
2. The pattern is placed (vertically) in the same position on each curtain, so the curtains match.

To do this we increase the fabric cut drop so the pattern starts and finishes at the same position on the fabric on a cut length, (creating identical drops when cut consecutively). This is called an ADJUSTED CUT DROP.

ADJUSTED CUT DROP

To calculate the Adjusted Cut Drop:

• Divide the Fabric Cut Drop (see plain fabric) by the vertical Pattern Repeat
• Round the result up to the nearest whole number
• Multiply the whole number by the vertical Pattern Repeat
• You now have the Adjusted Cut Drop (ACD)
• The Adjusted Cut Drop is also a whole number of vertical pattern repeats, make a note of both the length and number of pattern repeats for use when measuring cut drops in STEP 6.

So in this example the Adjusted Cut Drop (ACD) is 286.2cm and 9 Pattern Repeats

In calculating the adjusted cut drop we have effectively increased the Plain Fabric Cut Drop length so it is a whole number of pattern repeats. This means when the fabric is cut from the roll, a cut drop will start and finish at the same point on the pattern. Thus by cutting the adjusted cut drops consecutively each cut drop will be identical starting and finishing at the same point on the pattern. They will then match and join when placed along side each other.

Note: adding an extra pattern repeat to the total is optional. With some random patterns this may not be necessary.

FABRIC QUANTITY REQUIRED (Patterned Fabric)

To calculate the amount of patterned fabric required to make a pair of curtains:

(NUMBER OF FABRIC WIDTHS x ADJUSTED CUT DROP) Plus add one PATTERN REPEAT

Adding one vertical pattern repeat to the total allows you to choose where the pattern starts on the curtain.

PHEW!! WE'VE MADE YOU A CALCULATOR

To help check your results and make the process easier or if you don't like maths we've made this calculator for calculating curtain fabric and lining quanities.