To calculate the dimensions of your curtain and then the fabric quantities, you first need to consider.

• FULLNESS RATIO
• EASE & OVERLAP
• PLEAT DEPTH
• HEM SIZE

FULLNESS RATIO

The fullness ratio of a curtain determines how full or skimpy it will be. Fullness ratio is the ratio of the "width of fabric used to make a curtain" to the "width of the pole". We recommend a fullness ratio of 2.2 to 2.4 for lined double pleat curtains

Please see our FULLNESS RATIO GUIDE for more information on fullness ratio and the situations where we may vary from these figures.

EASE & OVERLAP

If you made your curtains to the exact width of the pole or track, they would spring back when pulled together leaving a gap. For this reason we make them slightly wider than the pole/track. We add 10% to the distance the curtain will cover on the pole/track for ease and to create an overlap. (note we add a minmum value of 10cm)

CHOOSE YOUR PLEAT DEPTH

This is a design decision. Note you can cut buckram down if needed.

The depth of your pleats is determined by the depth of the buckram you use and will have a small affect on the amount of fabric you require (as calculated in step 3).

For guidance generally we would make sill length curtains with a 10cm (4") buckram and floor length curtains with a 12.5cm (5") or sometimes 15cm (6") buckram.

CHOOSE YOUR HEM SIZE

We use a double (folded up twice) 10cm hem for full length curtains and a double 8cm hem for sill length.

CALCULATION

FINISHED CURTAIN LENGTH

The "finished curtain length" is the length of the curtain from top to bottom after it has been made.

The finished curtain length for each curtain is "hook drop" plus "hook to top" measurements.

CALCULATION

FINISHED CURTAIN WIDTH

The "finished curtain width" is the width of the curtain after it is pleated and made.

For a pair of curtains the finished curtain width for each curtain is half the pole length plus 10% for ease and overlap. (note add a minimum of 10cm)

Note 1: 10% is less than 10cm so we use the minimum value of 10cm.

Note 2: If you are making a single curtain rather than a pair. The calculation for the finished curtain width is Pole length plus 10%.

CALCULATION

NUMBER OF WIDTHS OF FABRIC REQUIRED

To calculate the number of fabric widths to make a pair of curtains.

1. Multiply pole length by chosen fullness ratio
2. Divide result by fabric width*
3. Finally round this figure up (sometimes down) to the next whole number**

*Usable fabric width - this is the joinable width of the fabric and is what is generally quoted by suppliers. It is usually approx 137cm.

**If the result is close to a whole number in some cases we may round down but the curtain will lose fullness (see below).

NUMBER OF WIDTHS = (Pole length x Fullness Ratio ) ÷ Width of fabric

GUIDANCE ON ROUNDING UP OR DOWN THE NUMBER OF WIDTHS

How close the result is to a whole number determines how close that number of widths will be to your chosen fullness ratio. Rounding down decreases fullness ratio, leads to a skimpier curtain (bigger spaces/smaller pleats) but saves fabric. Rounding up increases fullness ratio and makes fuller curtains (bigger pleats/smaller spaces).

In some cases there is a judgement to be made as to whether the rounding up or down takes you too far from your ideal fullness ratio and hence your ideal pleat and space size. In that instance we would use an ADVANCED METHOD and look to cut the joined fabric panel to a calculated width to give us our chosen fullness ratio.