How Much Curtain Fabric Do I Need? Understanding Curtain Fullness

One of the questions I'm often asked when someone has chosen their curtain fabric is:

“How many metres do I need?”

It sounds like it should be a straightforward calculation. Measure the window, measure the drop and work out the amount of fabric.

Unfortunately, it isn't quite that simple.

The amount of fabric needed for made-to-measure curtains depends on several things, including the width of the window or track, the finished drop, the width of the fabric, the pattern repeat and — importantly — the fullness of the curtains.

Understanding fullness is useful because it explains why two curtains for exactly the same window can require quite different amounts of fabric.

What does curtain fullness mean?

Curtain fullness is simply the amount of fabric used to cover the width of your window when the curtains are closed.

The finished curtains aren't made from a single flat piece of fabric the same width as your window.

Instead, extra fabric is gathered or folded into pleats, waves or gathers.

The more fabric you use, the fuller the curtains will appear.

For example, if your track is 200cm wide and you use 2x fullness, you're allowing approximately 400cm of flat fabric across the finished pair of curtains.

That's before allowing for hems, pattern repeats and other construction requirements.

Why do curtains need fullness?

Without fullness, curtains would look very flat and wouldn't hang properly.

Fullness creates the folds and gathers that give curtains their shape.

It also affects how the curtains look when they are closed and how they stack when they are pulled back.

This is one of the reasons I don't recommend choosing fabric based simply on the width of your window.

The finished curtain is a carefully constructed piece of soft furnishing, not simply a piece of fabric cut to the size of the glass.

How much fullness do curtains need?

There isn't one fullness that works for every curtain heading.

As a general guide, many pencil pleat and eyelet curtains are made at around 2x fullness, while pinch pleat curtains can require around 2.5x fullness. Wave curtains work differently because the fullness is determined by the wave system and glider spacing.

The exact amount I would recommend depends on the style you're trying to achieve and the system being used.

More fullness generally creates a richer, more luxurious appearance, but it also means more fabric — and therefore a higher fabric cost.

Why does the width of the fabric matter?

Curtain fabrics aren't all the same width.

Many fabrics are around 137cm wide, but widths vary, and some specialist fabrics can be considerably different.

This matters because the fabric needs to be divided into workable widths to create the curtains.

For example, if your calculations require 2.4 widths of fabric, you can't order 2.4 widths.

You need to allow for the required number of complete fabric widths.

This is why a seemingly small change in the width of a window can sometimes change the amount of fabric required.

What difference does a pattern repeat make?

Pattern repeat can make a surprisingly big difference.

If you've chosen a plain fabric, the curtain maker can simply calculate the required drop and allowances.

With a patterned fabric, the pattern needs to be matched correctly from one curtain width to another.

If a fabric has a large vertical pattern repeat, additional fabric may be needed so that the pattern lines up correctly.

This is particularly important with large florals, stripes and geometric patterns.

It's one reason why I always recommend checking the fabric requirements before ordering.

Does the curtain heading affect the amount of fabric?

Yes.

Different headings create different effects and require different amounts of fabric.

For example, pencil pleat, pinch pleat and wave headings don't all use fabric in exactly the same way.

A wave heading also requires the correct track and spacing system, so the fabric calculation needs to be based on that particular system.

This is another reason why the curtain heading should be decided before the fabric is ordered.

Why can two curtains for the same window cost different amounts?

Imagine two customers have exactly the same size window.

One chooses a plain fabric with a small repeat, a standard lining and a simple heading.

The other chooses a wide-width designer fabric with a large pattern repeat, a fuller heading and interlining.

The windows are identical.

But the amount of fabric, construction and lining required could be very different.

That's why it isn't possible to give a meaningful curtain price simply by knowing the size of the window.

Does a bigger drop mean more fabric?

Yes.

The longer the curtains, the more fabric is needed for each width.

And you also need to allow for hems and, where applicable, pattern matching.

A pair of floor-length curtains can therefore require considerably more fabric than a pair of curtains finishing at the windowsill.

This is particularly noticeable in rooms with high ceilings.

Why I don't recommend ordering curtain fabric before it has been calculated

This is one area where it is very easy to get caught out.

You might measure your track, look at the fabric width and think you've worked out how much you need.

But once you take into account:

• Fullness

• Pattern repeat

• Hems

• Heading

• Fabric width

• Matching

• Finished drop

the calculation can be very different.

And if you've ordered too little fabric, you may not be able to get more from the same dye batch — or the fabric may have gone out of stock altogether.

It's always better to calculate it properly before ordering.

Does more fullness always mean better curtains?

Not necessarily.

More fullness can create a beautiful, luxurious look, but it isn't automatically the right choice for every room or every heading.

The style of the room, the fabric and the type of curtain all need to be considered.

A contemporary wave curtain, for example, has a very different appearance from a traditional pinch pleat curtain.

The aim isn't simply to use as much fabric as possible. It's about creating the right proportions for the room.

The bottom line

There is much more to calculating curtain fabric than simply measuring the window.

The width, drop, fullness, fabric width, pattern repeat and heading all need to be considered before the final amount of fabric can be calculated.

And this is one of the advantages of having curtains made to measure.

The fabric can be selected and calculated specifically for your window and the style of curtain you want, rather than trying to make a standard size work.

At Indiana Rose Interiors, I can talk you through the different heading, fullness and lining options and work out exactly what is needed for your curtains.

Getting the calculation right at the beginning means you can order with confidence — and avoid the very expensive mistake of running out of fabric halfway through making your curtains.