• - Fabric
  • - Lining
  • - Thread
  • - Buckram
  • - Wadding
  • - Weights
  • - Curtain Hooks
  • Tools
  • - Sewing Machine
  • - Needles
  • - Pins
  • - Clamps
  • - Scissors
  • - Set Square
  • - Straight Edge
  • - Invisible Marker
  • Step 3: Calculate Fabric Quantity
    Printable Worksheet
    Printable Worksheet

    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 or down 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. Rounding down results in less full curtains and if using a fullness ratio of 1.9 the curtains can be too thin if you round down.


    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

    Extra Help & Comments

    for eg calculation for number of fabric widths you have put the fullness ratio as 2.0 as in double pleat.
    you had mentioned the F.R as 2.5 for triple pleat curtain.
    Can you change that please.
    Kind Regards
    Sew Helpful
    All changed.

    Thanks for the feedback 
    I have a pole of 1.5 metres and a curtain which i would like to change the heading to, (was pencil pleats) but am now looking at cartridge, the curtain i have is 4 metres in width should i reduce this to 3 metres or would 4 metres be ok
    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?
    Sew Helpful
    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.

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