•   Sewing Machine
  • - Tape Measure
  • - Needles
  • - Pins
  • - Scissors
  • - Set Square
  • - Straight Edge
  •   Pencil
  • - Vanishing Marker
  • - Clamps
  • Step 3: Calculate Fabric Quantity

    Fabric is ordered in a length of metres cut from the roll. Before calculating fabric quantities you will need the following:

    With this information we :

    • Calculate the NUMBER OF WIDTHS OF FABRIC required to make the pair of curtains
    • Calculate the FABRIC CUT DROP
    • Then Calculate* the amount of FABRIC REQUIRED.

    * Note: The final calculation depends on whether the fabric is PLAIN or has a PATTERN.


    To calculate the number of fabric widths required to make your curtains:

    • Multiply Pole Length by Fullness Ratio.
    • Divide this figure by the Fabric Width.
    • Round the result up to the nearest whole number*.
    • This whole number is the number of widths you require to make your curtains.
    * Note: When rounding up or down you are slightly increasing/decreasing the fullness of your curtains. We do not round down below 2.5 fullness ratio for a triple pleat curtain. We round up then cut the panel down to a 2.5 fullness ratio if we had to round up excessively.


    To calculate the Fabric Cut Drop

    * We also add a 5cm trimming allowance for PLAIN FABRIC to enable us to straighten the ends of the cut lengths, we dont for PATTERN FABRIC as there is usually extra fabric in the ADJUSTED CUT DROP.

    PLAIN and PATTERNED FABRIC are treated differently at this stage


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

    • Multiply the "Number of fabric widths" by Fabric Cut Drop.

    Alternatively try our online calculator.


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

    When the fabric has a pattern we also have to take into account that the pattern will need to line up where we join fabric and the pattern will need to be in the same position on each curtain.

    To enable this we adjust the fabric cut drop so we can get a cut drop starting at the same pattern position each time.


    To calculate the Adjusted Cut Drop:

    • Divide the Fabric Cut Drop 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, note this number down for use in measuring cut drops in step 6.


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

    • Multiply the "Number of fabric widths" by Adjusted Cut Drop.
    • Add one vertical pattern repeat (this allows you to choose where the pattern starts)

    Alternatively try our online calculator.

    This video explains
    • The difference between half drop pattern repeat and normal pattern repeat
    • Adjusted cut drop

    Questions & Comments


    Hello, In your example of fabric widths, your answer comes to 3 widths. Does this mean that 1 width will have to be cut in half to be joined to the other 2?


    Yes for a pair each curtain will be 1.5 widths, so you cut one in half.


    HI - Does the hem allowance for full length of 20 cm include the side hems and seams? I guess they are about 15-20 cm?


    No the hem allowance is for the hem and is for calculating lengths not widths. 

    We calculate the number of widths of fabric needed to give your curtain the correct fullness when pleated. The side turns on the fabric are found in STEP 7 they are 5cm.

    Sharron Boog-Scott

    Do triple pleat curtains require more fabric than double pleat? ie is the pleat the same but just folded differently?

    I used the calculator and discovered that the fabric requirements were the same for both. I want to get started, not sure which pleat to choose, or which tutorial to purchase, but wonder if the tutorials are the same up to the last formation of the pleats stage


    Triple pleat does require more fabric than a double pleat. you are not changing your fullness ratio in the fabric calculator when calculating for each pleat. We recommend a fullness ratio of 2.5 for triple pleat and 1.9 to 2.2 for a double pleat.

    The tutorial method is the same up to the folding of the pleat. The pleats are similar but obviously not the same.

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