How to Measure Your Windows for Made-to-Measure Blinds

Getting your measurements right is the single biggest factor in how well a made-to-measure blind fits and performs. Get it wrong by even a centimetre and you can end up with light gaps down the sides, a blind that won’t close properly, or one that simply doesn’t fit the recess at all. The good news is that measuring properly takes ten minutes and just a few simple tools.

What you’ll need

• A metal tape measure (fabric tape measures stretch and aren’t accurate enough)
• A pencil and paper, or your phone’s notes app
• Someone to help steady the tape on larger windows

Recess fit or face fit?

The first decision is whether your blind will sit inside the window recess (a neat, built-in look, ideal when you have at least 6–7cm of usable depth) or be fitted to the wall or window frame outside the recess (better for shallow recesses, or when you want the blind to fully block light by overlapping the frame). This decision changes how you measure, so decide first.

Measuring for a recess fit

1. Width: measure the recess at the top, middle, and bottom. Recesses are rarely perfectly square, so always use the narrowest of the three measurements — this is the width we’ll make the blind to, minus a small tolerance (usually 1–1.5cm total) so it doesn’t bind against the sides.
2. Height (drop): measure from the top of the recess down to the sill at the left, middle, and right. Use the longest measurement so the blind fully covers the window at its deepest point.
3. Depth: check you have enough clearance for the brackets and headrail, especially if there are handles, hinges, or a windowsill lip that could get in the way.

Measuring for a face fit

1. Width: measure the width of the recess (or the area you want to cover) and add at least 10–15cm — around 5–7.5cm extra on each side — so the blind overlaps the frame and blocks light from creeping in at the edges.
2. Height: measure from where you want the top of the headrail to sit down to where you want the blind to finish, typically to the sill or a little below it.
3. Fixing surface: make sure there’s solid wall, frame, or a pelmet board wide enough to take the brackets across your new, wider measurement.

Common measuring mistakes

• Measuring only once, in the middle — always take three measurements and use the narrowest (width) or longest (drop) as your working figure.
• Forgetting to allow for obstructions like door handles, radiators, or window handles that protrude into the recess.
• Using a fabric tape measure, which stretches slightly and can throw off a fit by several millimetres.
• Rounding measurements up or down “to the nearest whole number” — precision matters more here than almost anywhere else in home furnishing.

Why we still measure for you

Even with a careful DIY measure, we always carry out our own measure and survey before manufacturing begins. Every window in an older London property tends to be very slightly out of square, and our fitters know how to account for that, plus any quirks specific to the product you’ve chosen — whether that’s a chain-operated roller blind, a motorised system, or a set of interior shutters. Think of a DIY measure as a great way to get an accurate quote quickly; our site visit is what guarantees the final fit. Bay windows need particular care — see our guide to dressing bay windowsfor why. And if you’re still deciding between made-to-measure and a ready-made blind, our made-to-measure vs ready-made comparison covers exactly how much fit matters.