How To Measure For Curtains And Blinds (a step by step guide)

Most people get their measurements wrong in the same three ways. We know because we have been making and fitting curtains and blinds for homes around Sutton Coldfield for years, and we see the same notes come through on the same scraps of paper. Nobody is being careless. It is just that measuring a window is not really measuring a window at all, and that catches people out.

So here is how it actually works. Read this before you order anything, because with made-to-measure curtains there is no returning them if the drop is 8cm out.

What you need before you start

A steel tape measure. Not a fabric one, and not a phone app. Fabric tapes stretch over a long drop and you can lose a couple of centimetres without noticing.

Work in centimetres, write everything down as width first then drop, and label each window by room. If you have two windows that look identical, measure them both anyway. In a 1930s semi we quite often find 2cm to 3cm of difference between two windows in the same bay. Houses move.

You also need to know your pole or track before you measure, which is the bit most guides skip over.

Measuring for curtains: start with the pole, not the window

This is the big one. Curtains hang from the pole or the track, so the pole is what you measure. The window opening barely matters.

If your pole is already up, measure the length between the finials, the decorative ends. That is your width. For a track, measure the full length of the track including any overlap arm.

If the pole is not up yet, decide where it goes first. Where the wall allows it, we fit poles so they extend around 15cm to 20cm past each side of the window. That gives the curtains somewhere to stack back to when they are open, so you get the full window and the full daylight rather than fabric sitting across the glass. Height wise, around 10cm to 15cm above the top of the window recess works for most rooms. Higher makes the window look taller, which is worth knowing if you have squat windows.

We supply poles and tracks alongside the fabric for exactly this reason. You can see the range on our accessories page.

Measuring for curtains: working out the drop

Measure the drop from the bottom of the curtain ring, not from the pole itself. Get that wrong and every curtain in the house sits a couple of centimetres too low. For a track, measure from the top of the track.

Then pick where you want the curtains to finish. There are really only three sensible answers:

• To the sill, finishing about 1cm above it so the hem does not catch and wear.
• Below the sill, usually around 15cm down, which suits kitchens and smaller bedrooms.
• To the floor, finishing 1cm clear of the carpet.

Here is something worth thinking about that hardly ever gets mentioned. If you have a radiator under the window, floor length curtains will trap the heat behind the fabric and send most of it up the glass instead of into the room. It looks lovely and it costs you money all winter. A sill length drop, or a shorter interlined curtain, is often the better call. We would rather tell you that at the measuring stage than after.

If you want a puddled finish, add 10cm to 20cm to the floor measurement depending on how dramatic you want it. And in older houses, measure the drop at both ends and in the middle. Floors slope, and a 3cm slope across a bay is very visible once the curtains are up.

How much fabric you actually need

Curtain width is not the same as pole width. You need fullness, which means gathering more fabric than the space it covers. As a rough guide, pencil pleat and pinch pleat headings want around 2 to 2.5 times the pole width. Wave and eyelet headings sit closer to 1.8 to 2.3 times, because they fold differently.

Patterned fabric adds another layer. The pattern repeat has to line up across every width and across every window in the room, so a fabric with a 64cm repeat can quietly push you into buying an extra width of fabric. This is why two fabrics at the same price per metre can end up costing very different amounts by the time they are made up. Ask about the repeat before you fall in love with a print. We work with Harlequin, Romo, Sanderson, Morris and Prestigious among others, and the repeat is always on the sample.

How to measure for blinds

Blinds are a different job because they usually sit inside the window recess, so precision matters more.

For a recess fit, measure the width in three places, at the top, the middle and the bottom. Use the smallest of the three. Then measure the drop on the left, in the centre and on the right, and use the longest. Recesses are rarely square.

Give us the exact recess size and tell us it is a recess fit. Do not take an allowance off yourself. The workroom deducts a small amount, usually around 10mm to 15mm in total, so the blind runs freely without scraping the plaster. If you deduct as well, you end up with gaps of light down both sides.

For a blind fitted outside the recess, add 5cm to 10cm either side and around 10cm above the opening.

Before you write anything down, look at what is in the way. Window handles, tiled sills, pipe boxing and window openers all affect whether a blind will sit flat. Roman blinds need a decent stacking depth at the top when raised, and roller blinds need clearance for the barrel. Our full range of Roman, roller and wooden blinds is here if you want to see the options first.

The mistakes we see most often

Measuring the glass instead of the pole. Guessing the drop from a photo. And assuming that because two windows were built at the same time, they are the same size.

When to just let us do it

Honestly, this is the part where we would say get someone in. Not because measuring for curtains is difficult, but because the responsibility sits in the wrong place when you do it yourself. If we measure and something is wrong, we fix it. If you measure and something is wrong, the fabric is already cut.

We offer a free home visit across Sutton Coldfield and the surrounding areas, samples included, and every set of curtains and blinds comes with a five year guarantee. Have a look at the gallery to see how it comes out, then give us a ring on 0121 355 2723 or use the contact form and we will sort a time that suits you.