How much fabric do I need for Curtains with a heading tape

How much fabric do I need for curtains? – This is the first question you will ask after you’ve decided to make your own curtains.

In this tutorial I want to share with you how to measure your windows and calculate fabric for tape headed curtains, how to work with fabrics that have pattern, what factors you need to take into account when deciding whether to line your curtains or not and many other tips and techniques you will need to be equipped with when you start making your own  curtains.

The very first step to take in making curtains is to decide on the length of the curtains.

There are four standard lengths: the sill length – curtains finish ½”/1cm above sill, the radiator length – curtains finish 4”/10cm below sill,  if the curtains you are making are floor length, allow ½” to 1” clearance between the lower edge of your curtains and the floor and if you want to give your room a relaxed look with curtains paddling on the floor add approx 20” to the floor length.

Before you start

If you have a number of windows in the same room measure for all curtains in the room to be the same height from the floor – curtains of same length will give your room a harmonised stylish look.

When measuring for curtains, it would be helpful if the poles or tracks are in place before you begin – you will get more accurate measurements with curtain hardware already installed over your window. So select and install the hardware you want before measuring for window curtains.

Then choose your fabric as you will need to know the fabric width and fabric thickness for your calculations: for lightweight fabric you can use 2 to 3 times fullness, the heavier fabrics will need less fullness to look full.

The next step is to choose the heading tape as that affects the width of the curtains. For instance, pencil pleat curtains require a fabric width of 2.5 times the length of the track or pole, a simple gathered tape requires 1.5 times the length of the track and pinch pleats – 2 times the track length.

How to measure windows for curtains and estimate the fabric required

This step is the most difficult if you have never done it before and it is also very important. Remember the old saying: “Measure twice and cut once”?

To estimate the fabric you need to know two figures: the number of widths required and the cut length of your curtains.

Calculating the fabric width for curtains

  • Measure the length of your curtain pole (do not include the finals – the decorative pieces on the ends).
  • Multiply the figure by fullness ratio (usually 2 to 2.5 times).
  • Divide the result by fabric width (54” is quite common but can be up to 120”).
  • Round up to the nearest whole number.

Example:

Pole length – 80” / 203cm

Fullness ratio – 2

Fabric width – 54” / 137cm

Number of fabric widths required – 80”x 2 : 54” = 2.96

Round up to the nearest number = 3 widths.

Calculating the cut length of curtains

Determine the desired (or finished) length of your curtains. The finished length is measured:

  • For Poles with rings – from the bottom of the curtain ring to the desired drop;
  • For Eyelet poles – from the top of the pole to the desired drop, then add 1.5” (4cm) for the fabric that sits above the pole;
  • For Tracks – from the top of the track (to ensure the curtain will hide the track) to the desired drop.

When measuring the drop, take measurements in several places: from the middle of the pole and from the sides of the pole – in case your floor or window sill is not level you will need to adjust the length of the curtain accordingly.

The cut length is equal to finished (or desired) length of the curtain + 2” for the upper hem + bottom hem allowance.

                Bottom hem allowance

  • Sill length curtains                            6” / 15cm
  • Floor length curtains                        8” / 20.5cm
  • Curtains paddling on the floor       1” / 2.5cm

When working with a patterned fabric add the length of one repeat pattern to each fabric width. The pattern repeat is usually indicated on the selvage of the fabric or can be measured on the fabric.

Example 1:

Finished curtain length – 62” / 157cm

Heading allowance – 2” / 5cm

Bottom hem allowance – 6” / 15cm

Pattern repeat – 23”

Cut length – 62”+2”+6”+23”=93”

Example 2:

Finished curtain length – 92” / 234cm

Heading allowance – 2” / 5cm

Bottom hem allowance – 8” / 20.5cm

Pattern repeat – 23”

Cut length – 92”+2”+6”+23”=123”

Calculating the fabric required

Now, multiply the cut length of curtain by number of fabric widths and this is the length of fabric required for your curtains.

Example:

For the curtain from the Example1:

93” x 3 = 279” (divide by 36 to arrive to yardage)

For the curtain from the Example2:

123” x 3 = 369”(divide by 36 to arrive to yardage)

Cutting fabrics with pattern

If your fabric has a pattern: Before you cut your first curtain panel you need to decide on the best position for the pattern in regards to the top and bottom of the finished curtain.

  • Choose one main point in the design and mark off your first length starting at this point. The length of this panel should be equal to the finished length of your curtain plus seam allowance.
  • Cut the first drop of curtaining and leave it face up on your working space.
  • Roll out the second length.
  • Match the pattern carefully by aligning one of the edges and checking the pattern exactly matches between the two pieces of fabric.

Lined curt 1

  • Cut the second length of the fabric to the same length.

Joining the widths of face fabric

If you need to join widths to make up each curtain:

  • Pin the fabric pieces together along the selvages with right sides facing. If you have an odd number of fabric widths, cut the ‘odd’ piece in half lengthways and pin one half to the outside edge of each curtain.
  • Stitch the pieces together.
  • Press the seams open.

Joining the widths of face fabric with pattern

  • Lay fabric widths right sides together matching selvages.
  • Fold back the upper selvage until the pattern matches.
  • Press the foldline.

Matching fabric pattern

  • Unfold the selvage and pin the fabric widths together on foldline.

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  • Check the match from right side.
  • Re-pin the fabric so the pins are perpendicular to the foldline.
  • Machine stitch on the foldline.

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Dealing with selvages

Because the selvages are constructed differently than the rest of the fabric, they may shrink at a different rate than the rest of the fabric when washed. So it is usually better to cut them off to prevent curtain puckering or twisting at the edges.

However, sometimes it is much easier to match the curtain pattern by stitching the two pieces of fabric together just inside the selvage, using it as a seam allowance. In that case, snip into the selvage ½” in or so at regular intervals. This will enable the fabric to lie flat, which is very important for making curtains.

Lined curtains vs. un-lined

Lined curtains have some distinctive advantages against un-lined curtains: lining will add extra fullness and give your curtains a more luxurious appearance, will help you with heat, sound and light insulation and also the lining will prevent your curtain from discolouring due to sun exposure through the window.

Un-lined curtains, on the other hand, are easy to look after, provide privacy but do not block all the light, simple to make and they are best used on windows where frequent washing is required such as kitchen or bathroom windows.

Pre-wash or not pre-wash the fabric

This is a very good question but unfortunately there is no straight answer to it.

What you need to take into account before you make your decision is:

  1. Whether the fabric is manmade or natural – fabrics made from natural fibres shrink when washed;
  2. Some decorator fabrics are treated with special finishes to resist dirt and retain the sheen which would be destroyed by washing – for curtains that will need to be washed, such as kitchen or bathroom, avoid using treated fabrics;
  3. Some fabrics may shrink even after they have been pre-washed.
  4. Washing curtains that have lining and interlining may result in uneven shrinkage due to different rates of shrinkage of the lining and interlining materials.

Hopefully you find this information useful and now you are ready to start making your own curtains.

If you want to know How to make lined curtains, please have a look at my next post.

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