Why We Measure Fabric Opacity, Stretch and Drape

Buying fabric online can be difficult. A photograph can show colour and pattern beautifully, but it cannot always tell you how transparent a fabric is, how much it stretches, or how it will hang and move when made into a garment or project.

That is why, at Sewing-Sanctuary, we are introducing three simple fabric properties to our product information: Opacity, Stretch and Drape.

Our aim is to give you a clearer idea of how a fabric behaves before you order it, using the same testing method and rating system across our range.

Opacity

Opacity tells you how much you can see through a fabric.

This can be particularly useful when choosing fabrics for dresses, skirts, tops, curtains or any project where coverage matters.

We assess a single layer of fabric under consistent lighting and compare how clearly a hand or contrasting background can be seen through it.

Our four opacity ratings are:

• Sheer – clearly see-through
• Semi-sheer – some transparency, with shapes or shadows visible
• Mostly opaque – good coverage, although a little transparency may be noticeable in bright light
• Opaque – little to no visibility through the fabric

You will see this shown on product pages using a simple four-part visual scale.

Stretch

Stretch tells you how much a fabric can comfortably extend.

Rather than relying on descriptions such as “a little stretchy” or “very stretchy”, we use a simple measured test.

We mark a 10 cm section of fabric, stretch it firmly but naturally without forcing it, and measure how far it extends.

The result is then placed into one of four categories:

• No stretch – under 5%
• Slight stretch – 5–19%
• Moderate stretch – 20–40%
• High stretch – over 40%

For example, if a 10 cm section comfortably stretches to 13 cm, that is approximately 30% stretch and would be described as Moderate stretch.

Stretch direction

How much a fabric stretches is only part of the story. The direction of the stretch can also be important, particularly for dressmaking.

We therefore also record whether the fabric has:

• None – no meaningful stretch
• Crosswise – stretches across the width, from selvedge to selvedge
• Lengthwise – stretches along the length of the fabric
• 4-way – stretches both across the width and along the length

This gives you a much clearer picture of how the fabric is likely to behave when cut and worn.

Drape

Drape describes how a fabric hangs, falls and forms folds.

Two fabrics can be the same weight but behave completely differently. One might hold its shape and stand away from the body, while another falls into soft flowing folds.

To assess drape consistently, we allow a standard-sized fabric sample to hang freely under its own weight and observe how readily it falls and how much shape it retains.

Our drape scale is:

• Crisp – holds its shape and resists falling into soft folds
• Structured – has some movement but retains noticeable body
• Fluid – falls readily into soft, flowing folds
• Very fluid – falls extremely freely and closely follows contours

An important point is that drape is not the same as weight. A lightweight fabric can be crisp, while a heavier fabric can have a beautiful fluid drape.

Why use a rating system?

Fabric descriptions can be subjective. Words such as light, flowy, stretchy or see-through can mean different things to different people.

By using a consistent testing process and a simple rating scale, we hope to make those descriptions more useful and easier to compare from one fabric to another.

The ratings are designed as a practical guide rather than laboratory specifications. Fabrics can also behave differently depending on colour, lighting, how they are cut, how much they are stretched, and the design of the finished project.

However, testing them in the same way gives you a much better starting point when choosing online.

Look for the information symbol

On participating fabric product pages you will see Opacity, Stretch and Drape listed under the product information.

Each property has a small ⓘ information symbol beside it. Select the symbol to see the full rating guide and compare where that particular fabric sits on the scale.

We hope these extra details make it easier to choose the right fabric for your project — and give you a little more confidence about what will arrive through your letterbox.