How to Measure for Made-to-Measure Blinds

Before you start

Most blinds that do not fit were measured from the wrong place, not with the wrong tape. This guide shows you where to measure for each type of fitting, what to write down and when to stop and ask us. It is the same method we use on a free home visit before we make blinds in our Rainham workshop. At the end there is a measurement sheet you can print and fill in.

The tools

1. A steel tape measure. A fabric tape stretches and sags, especially across wider windows.
2. A short steel rule, for small measurements such as bead depth and handle clearance.
3. A bank card, for the bead depth check on Perfect Fit windows.
4. A pencil and the measurement sheet at the end of this guide.
5. A second person for windows wider than you can comfortably reach.
6. A phone camera, so you can photograph each window and anything unusual about it.

General rules for every blind

These rules apply whichever blind you choose.

1. Use a steel tape and keep it straight and flat.
2. Measure in millimetres, not centimetres or inches. Round to the nearest millimetre.
3. Measure the width three times, at the top, the middle and the bottom.
4. Measure the drop three times, on the left, in the centre and on the right.
5. Write all three figures down, then use the smallest of each.
6. Measure every window and every pane separately. Windows that look the same are often a few millimetres different.
7. Do not deduct anything yourself unless the guide for your fitting type tells you to.
8. Label every measurement with the room and the window, for example "Bedroom 2, left pane".

Perfect Fit blinds

A Perfect Fit blind clips onto the glazing bead of a uPVC window and is made to the size of the glass, not the recess. The bead is the strip that holds the glass in place, with a rubber seal between it and the glass.

Glass to bead.

1. Find the point where the glass disappears under the rubber seal on the left.
2. Measure across to the same point on the right. That is one width.
3. Repeat at the top, middle and bottom. Use the smallest.
4. Measure the drop the same way, from the seal at the top to the seal at the bottom, on the left, centre and right. Use the smallest.
5. Do not deduct anything. The allowance for the frame and brackets is built in when the blind is made.

If the seals stick out over the glass by more than a few millimetres, the right measuring point depends on whether the seals are soft or solid. If your seals look unusually wide, photograph them and send the picture to us.

Bead depth check.

The bead depth is how far the face of the window frame sits back from the glass. It decides the size of bracket your blind needs.

1. Lay a bank card flat across the corner of the frame so it bridges the bead.
2. Measure from the glass to the underside of the card.
3. Write it down to the nearest millimetre.

Common depths are 18 mm, 20 mm and 24 mm, but older or chunkier frames can sit outside that, so always measure. Check your blind's own instructions for the depths it accepts.

You also need a flat strip of frame all round the outside of the bead for the blind frame to sit on. Check your blind's own instructions for the space it needs.

Handle clearance.

The blind frame sits on the same part of the window as the handle, so the handle can get in the way.

1. With a steel rule, measure from the edge of the glass, where it meets the seal, across to the nearest edge of the handle base.
2. Note which side the handle is on.
3. Do the same for any trickle vent or restrictor near the glass edge.

Each system sets its own minimum gap between the edge of the glass and any obstruction such as a handle, so check your blind's own instructions or tell us the figure. If your handle is too close, a handle spacer or a slimline handle can often solve it, and we can advise.

Recess blinds and exact-size blinds

Standard roller, Roman, Venetian and vertical blinds can sit inside the window recess or outside it. When you order, you tell us whether your figures are the recess size or the exact size of the blind you want.

Recess size. You give us the inside measurements of the recess, wall to wall and top to sill, using the smallest of three readings each way. We take a small allowance off when the blind is made, so it runs freely without rubbing the walls. Do not take anything off yourself.

Exact size. You give us the finished size of the blind itself, and we make it to that figure with nothing taken off. This is usually used for face fit blinds, or when you are replacing a blind and know exactly what you want.

Recess depth.

For a blind inside the recess, you also need the recess depth.

1. Measure from the window frame, or from the glass if the frame is flush, forward to the front edge of the recess.
2. Check it in a few places, because plaster is not always even.
3. Note anything that sticks out into the recess, such as handles, tiles or a deep sill.

Each type of blind needs a different depth to sit inside the recess, and double rollers need more than single blinds. Check your blind's own instructions, or tell us the figure and we will confirm what fits. If the recess is too shallow, a face fit is usually the answer.

Face fit blinds

A face fit blind is fixed to the wall or frame above the window, outside the recess, so it covers the whole opening.

1. Measure the width of the opening, then decide how far you want the blind to overlap on each side. A wider overlap blocks more light at the edges.
2. Measure the drop from where the brackets will go, usually above the recess, to where you want the blind to stop, either on the sill, below it or at the floor.
3. Give these figures as an exact size.
4. Check that nothing gets in the way of the overlap, such as a radiator, curtain pole, light switch or tiled reveal.

Roof windows

Roof windows need blinds made for that specific window, so you do not need to measure them at all. You read the code from the window instead.

1. Open the ventilation flap at the top of the window.
2. Look for the type sign in the right-hand corner of the top sash, behind the flap.
3. Write down the full code. It shows the window's type, size and variant, plus a production code.
4. Photograph the sign so nothing is copied wrongly.

If you cannot find or read the sign, we can read it at the free visit.

Double roller blinds

A double roller has two rollers on one bracket, usually a blackout fabric and a sheer, each with its own chain.

1. Measure width and drop in the same way as a single blind, smallest of three each way.
2. Measure the recess depth carefully. Two rollers need noticeably more depth than one, and if the recess is too shallow, the blind is face fitted instead.
3. Decide whether both rollers need the same drop. A blackout roller might go to the sill while the sheer stops higher, or the other way round. Write both drops down.
4. On a tilt and turn window, check that the handle can turn freely with the bracket in place.
5. In a bay, measure each section on its own. Each one gets its own blind.

Measurement sheet

Print this page and fill in one row per pane. Write every figure in millimetres. For Fit type, write Perfect Fit, Recess, Face fit or Roof window. Use Notes for handle clearance, recess depth, handle side and anything unusual.

The PDF has a full printable sheet with eight rows. Download the measurement sheet.

Let us measure for free

If your windows are bays, tilt and turn, out of square, or you simply want to be sure, let us do it. Our home measuring visit is free. We measure every pane, check every bead, handle and recess, and bring samples so you can see fabrics in your own light. Your written quote is emailed or phoned through after the visit. We have been measuring and fitting across East London and Essex since 2015.

References

1. Child safety: blind cords. Office for Product Safety and Standards (GOV.UK). Retrieved 25 October 2026.
2. BBSA supports Child Safety Week to raise awareness of window blind safety. British Blind and Shutter Association. Retrieved 25 October 2026.