measuring for curtains and blinds

The Ultimate Guide to Measuring for Curtains and Blinds.

Measuring up is truly where the magic is when it comes to creating stunning curtain and blind installations.

Whilst accurate curtain and blind measuring is, of course, vital, it is so much more than that. It is at this stage that opportunities are spotted, that future problems are avoided, and that bold ideas are born!

Read on to get complete confidence and ensure you are delighted by your window dressings for years to come.

The magic is in the measuring up for curtains and blinds.

Measuring up for curtains and blinds is something to be taken very seriously, and there are three really good reasons for this:

1.   If you get the measurements wrong and go ahead and order your curtains or blinds, it may not be possible to change without a complete re-make. It is a great way to turn a ‘cheap’ online purchase into an eye-watering expense when you have to do it all over again.

2.   We also often see issues where curtains or blinds do not work effectively after being measured incorrectly. The track or pole is too narrow, or the curtains or blinds can’t function properly because obstructions have not been considered. If you are trying to achieve the perfect blackout for your bedroom, then accurate measurements are essential.

3.   Taking time at this stage to consider your window-dressing more widely will almost always provide exciting opportunities to optimise the finished look and style and dial up the joy you’ll get every day.

Top tip: Placing your curtain pole a good distance above the window can transform your curtains into a dramatic statement rather than a light-reducing necessity.

If you don’t consider this at the measuring stage, you will never have the option.

Whilst this guide on measuring your windows for curtains and blinds is all about accurate measuring, there are a few essential steps to work through before you even reach for your tape measure. Taking the time to assess the window features and all your style options will make the measuring so much easier and the end results much better.

How to measure your windows for curtains and blinds – step 1:

Understanding window types

The first step when measuring for curtains and blinds is identifying your window type and any key features or considerations. For example, we need to know if your window is a straight window or a bay, whether it is a sash or casement window. There are many types of bay windows, including 2-bend, 4-bend, square and segmented bays, which will dictate the available hardware options.

If we are dressing doors, we need to know their opening configuration. For example, are they sliding or bi-folding? We also need to know if windows and doors open inwards or outwards.

Assessing the space we have around the window

The next consideration when measuring for curtains and blinds is the space above the window to house hardware such as tracks, poles and blinds. Is there coving on the ceiling and above the window which will prevent us from ceiling mounting the hardware?

Top tip: We need a nice flat surface above the window to fit the brackets for poles and tracks.

The next consideration is how much space there is on each side of the window for curtains to stack back or for blinds to overlap the window.

In most cases, we would recommend placing hardware, curtains, and roman blinds outside the window recess (this blocks less light during the daytime and also looks great). However, if there is a nice deep window recess, we will often use this space for sheer curtains (on top fixed tracks) or roller blinds (more space-efficient). In the case of dormer windows, we often have no choice but to site the window dressing inside the recess.

Looking out for obstacles when measuring for curtains and blinds

When we survey a window, we are also looking out for obstacles such as deep window sills, deep radiators, nearby wardrobe doors (can they still fully open once window dressings and hardware are fitted) or protruding window handles that we need to clear.

There’s a lot to consider when measuring for curtains and blinds, which is why we include a full site survey as part of our curtain making service so that our curtains and blinds fit beautifully and there are no nasty surprises or compromises on installation day.

Kensington Curtain Maker

Doing the measuring – blinds

The first consideration when measuring for blinds is whether to fit them inside or outside the recess, and this depends on several factors.


If space allows, privacy roller blinds, Roman blinds, and cafe curtains tend to be fitted inside the recess, as these dressings don’t darken the room.


Blackout roller blinds are also often fitted inside the recess because when up, they take up little space (and therefore light), often fit neatly into the recess, and give better blackout as there is less opportunity for light creep at the sides.


Whereas bulkier lined Roman blinds are often better outside the recess so that less light is lost from the room during the daytime, and positioning them above the window can make the window feel grander and also help with the blackout in bedrooms.

Measuring for blinds INSIDE the recess

When measuring for a blind that is to sit inside the recess, you will need to measure the width in 3 places, top, middle and bottom and the drop in 3 places, left, middle and right – you will take the narrowest measure so that the blind fits. If you need to clear window furniture such as handles, consider where to position the blind within the recess. If you have a roller blind, then having the fabric reverse-rolled will help clear protrusions.

Top tip: Make it clear when ordering that your measurements are recessed, as the manufacturer will take off a little tolerance to ensure the blind fits inside the recess.

Measuring for blinds OUTSIDE the recess

If your blind is going outside the recess, we would suggest either mounting it on the window frame or even above this on the wall or ceiling. This is a good idea to maximise light in the room during the daytime. The principles for blinds going outside the recess are the same: measure the width and drop in 3 places and the exact area you want to cover.

Top tip: In this case, make it clear when ordering that your measurements are the exact size of the blind so that the manufacturer makes the blind exactly the size.

Doing the measuring – curtains

The first step when measuring curtains is to measure the window width from frame to frame.

Bay window measuring tips

If it is a bay window, you will need to measure around the bay (or, if easier, measure each section of the bay and add them together).

Existing curtain track or pole

If you already have a track or pole in place that you plan to reuse, you would measure the curtain track (plus overlap arm if it’s a corded track) or pole width excluding finials – rather than the window.

New curtain tracks or poles

If a new track or pole is needed, we recommend adding 15 to 30cm on either side of the window so that the curtains can stack back off the window. The size of the curtain stack will vary depending on the size of the window opening and the available wall space on each side.

If you are fitting new curtain hardware in a bay window, you will also need to measure the angles so that the track or pole can be bent to the correct shape.

Another key measurement for new hardware is the required bracket depth, especially if curtains need to clear a deep radiator or sill.

Corded curtain track

If you plan to use a corded track, we also need to add additional width for the curtain overlap. If you have an uncorded track or pole, it’s best to add a small amount of additional width for spring back and tolerance.

Curtain returns

For a professional look (and improved bedroom blackout), you should also include curtain returns so they can be returned and hooked to the wall at each end. This is particularly important for curtain poles and tracks with a deep wall projection. For curtain poles, this will be the depth of the brackets plus 1cm, same for tracks.

Measuring the drop

The second step is to measure the curtain drop, but first, you will need to decide where you would like the curtains to reach: e.g., to the floor, just below the sill, or another length. If you have read our article ‘Best Blackout Curtains for Your Bedroom,’ you will know that we recommend full-length curtains for bedrooms as there is less opportunity for light creep.

Existing track or pole

If you already have a track in place that you plan to re-use, then you should measure from the top of the track (if curtains are to sit in front of the track), or below the track if curtains are to be underslung, to where you want the curtains to reach.

Pole with rings

If you have a pole with rings, then you measure from the bottom of the eyelet (the small eyelet at the bottom of the curtain ring) to the point you would like your curtains to reach.

Glider pole

If you have a glider pole (a pole with a track inside), you measure from the underside of the pole to the point you would like your curtains to reach.

Skim, break or puddle

For a really bespoke look you should consider whether you would like your curtains to just skim the floor, break on the floor (+2.5cm) or puddle (+5-7cm).

Top tip: if curtains are in a high traffic area such as a kitchen you may prefer the curtains to clear the floor so that they don’t pick up dirt from the floor.

No hardware in place

If you don’t already have hardware in place, you would need to consider where to place the track or pole. If space allows, we recommend 15 to 25cm above the window, especially in a bedroom, as the higher it is placed, the better the blackout.

Top tip: fitting the pole or track as high as possible (10cm below the ceiling or cornice) can add real drama to a room and help emphasise and enhance the ceiling height. Or try lining through the top of the curtains or blind with built-in furniture or another anchor point in the room.

Projection for brackets

Don’t forget to measure the depth of any deep window sills and radiators to make sure you order the correct brackets so that the track or pole has the correct projection to allow your curtains to hang freely.

Top tip: If you have a deep window sill or radiator to clear, a ceiling-fixed track (or pole) can be a really smart solution. The track can be positioned just where it clears the obstacle below, thus avoiding deep, unsightly wall-mounted brackets—but this isn’t advised if you have cornicing.

Measuring time is thinking time – are you up to date on the latest trends in fabrics and finishes? Do you know what automation is possible?

Our Guide to the latest trends is a great start.

The magic of measuring for curtains and blinds isn’t just in the measuring.

Top tip: This initial part of your window-dressing project is the only time you can really be free to consider all the options available and get inspiration from all possible sources.

When we measure up for clients, we also share the latest ideas in colours, fabrics, as well as finishing touches such as braids, tassels, and fun design tips.

If you want to be reassured that you will not make any costly or annoying mistakes and wish to experience a full professional curtain and blind consultation and measurement, then please be in touch.

Get the look