How to measure your space for window coverings

Window coverings are often an afterthought in the grand scheme of home furnishings.

But depending on which type you opt for, these “afterthoughts” can cost in the tens of thousands – and some leave no margin for error.

Taking measurements may seem pretty straightforward but, like most things, there is a right way and a wrong way to do it.

Owner of Regency Knights Martin Smith is an expert and says many people don’t realise that shifting walls, ceilings and window frames can impact your measurements.

“Most windows are not perfectly square or rectangular, and there are steps we in the industry take to ensure we adjust measurements accordingly. For instance, the space you have to work with might actually be 1200 mm wide at the top and 1190 mm wide at the bottom,” he says.

“For most products you will need to measure in three different places for both width and drop and make some industry standard deductions.

“A fraction of a millimetre can sometimes be the difference between success and failure, and the latter can cost you.”

There are also things you need to consider when choosing which furnishing to opt for.

“Take note of anything that may get in the way of the operation of the window furnishing. What is inside the reveal? A handle? A window winder? Will there be a key sticking out?” Martin says.

“You’ll need to look top to bottom, left to right, to know how much room you actually have there and which products will work best for your space.”

Here are Martin’s methods for determining the most accurate measurements for ‘inside reveal’ covers – blinds and shutters.

What you’ll need

• Pen and paper
• Reliable tape measure

Method

Roman blinds

For this style of covering, you need to measure the window opening in several places.

This is because the headboard at the top of the blinds is the same width as the fabric all the way down to the bottom of the blinds. As such, you must ensure you order the width of your “make size” to fit the narrowest part of the opening.

The length or “drop” is the opposite: if the window is longer on one side, generally opt for the longest measurement.

1. Measure the width at the bottom, middle and top of the opening. Jot down the smallest of the three measurements.
2. Measure the drop (length) on the far right, middle and far left of the opening. Jot down the longest of the three measurements.
3. You will need to make a deduction off the width. The industry standard for Roman blinds is 10 mm for width to get what’s called the “make size”. This is the size you should order your blinds in.
4. For drop, consider whether you want your blinds resting on the window sill or sitting off it a little, and deduct from your drop measurement accordingly. Most people prefer the drop to sit on the sill.
5. Decide which side you want the chain on. In bedrooms, consider placing this on the side of the blind closest to the door for the easiest route from the entrance to walk in and operate the blinds.

Roller blinds

The roller blind fabric and base rail are already 30 or 40 mm narrower than the spool and where the brackets go at the top of your reveal.

As such, you must ensure you order the width of your “make size” to fit the narrowest part of the opening.

The length or “drop” is the opposite: if the window is longer on one side, generally opt for the longest measurement.

1. Measure the width of the opening at the top of the window frame and jot down the opening size.
2. Make a 3 mm deduction from the width to meet industry standards.
3. Measure the drop (length) in one part of the window opening. This measurement does not need to be perfect, as roller blinds tend to contain excess fabric, and you can operate it in such a way to sit as you prefer.

Honeycomb Blinds

For this style of covering, you need to measure the window opening in several places.

This is because the width of the top of the blinds, the bottom of the blinds and the fabric are all cut the same.

As such, you need to ensure you order the width of your “make size” to fit the narrowest part of the opening and opt for the longest measurement you get for your length or “drop”.

1. Measure the width at the bottom, middle and top of the opening. Jot down the smallest of the three measurements.
2. Measure the drop (length) on the far right, middle and far left of the opening. Jot down the longest of the three measurements.
3. You will need to make a deduction off the width. The industry standard for honeycomb blinds is 3 mm to 4 mm to get your “make size”. This is the size you should order the blinds at. There is no deduction for the drop on honeycomb blinds.

Shutters

Shutters require more depth in your reveal, so ensure you have adequate depth to accommodate your “tilt rod”.

Shutters come with a frame that fits inside the window first and are rigid with no margin for error. You will need absolutely accurate measurements for shutters.

1. Measure the width at the bottom, middle and top of the opening. Jot down the smallest of the three measurements.
2. Measure the drop (length) on the far right, middle and far left of the opening. Jot down the smallest of the three measurements.
3. You will need to make a deduction off the width and drop of 2 mm to 3 mm each to get your “make size” for shutters.

Hints

1. Ensure there are no distractions. If anyone is talking to you, pause what you’re doing and resume when you can have your full attention on the job.
2. Take the time to place yourself to get a clean reading of your measurements. This may necessitate using a step ladder or moving furniture out of the way.
3. Once you have completed all measurements, take a short break and do them all again. Do not repeat a measurement right away, as you’re likely to repeat any mistakes.
4. If you have even a sliver of doubt, it’s best to call in the experts – it could save you a small fortune in the long run.

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