To measure for a roller blind, first decide whether the blind will sit inside the window recess (reveal fit) or on the wall over the opening (face fit), because that changes every measurement you take. Then measure the width and the drop in millimetres, measuring the width in several places, not just once, because window openings are rarely perfectly square.
The most common roller blind problems trace back to a measuring mistake, not a fitting one. They split into two groups. The first is simple slip-ups: adding or dropping 100mm, swapping width and height, or working in centimetres when the order needs millimetres. None of these can be undone once the blind is cut and assembled to size.
The second group is harder to spot, and it's about everything around the window rather than the glass itself. Sliding door handles, window mullions, and bulkheads above the opening all get in a blind's path. Skirting boards or tiles that stick out at the bottom can catch the bottom rail as it lowers. An online order form asks for a width and a drop, it never asks what's in the way.
Whether the blind sits inside the recess or on the wall in front of it isn't a finishing detail, it determines how you measure, so settle it first. A reveal fit goes inside the window recess for a neat, built-in look and suits most windows with enough depth. A face fit mounts on the wall and architrave over the opening, which covers the side light gaps a reveal fit always leaves, so it's the better choice for bedrooms and anywhere you want maximum darkness or privacy.
The reason this comes first is that the two fits are measured to different references. A reveal fit is measured to the inside of the recess and the blind is made slightly smaller so it can operate. A face fit is measured to cover the opening plus an overlap on each side and top, so it deliberately ends up wider and taller than the window. Measure for the wrong fit and the numbers are wrong from the start.
Measure the width in millimetres, and measure it in several places across the opening rather than trusting a single reading. Window openings are rarely perfectly square: reveals bow, plaster is uneven, and a span that measures one figure at the top can be a few millimetres different in the middle or at the sill. For a reveal fit, the blind has to clear the tightest point, so the narrowest measurement is the one that matters.
Width also has a ceiling: a single roller blind goes up to around 3,200mm wide. Wider openings are better split into two or more blinds than forced into a single oversized blind.
Measure the drop (the height) from the top fixing point to where you want the blind to finish, again in millimetres. Where the blind finishes is a real decision, to the sill, past the sill, or to the floor — and it interacts with anything protruding low down. A bottom rail measured to a sill will clash if a tile or skirting board sits proud of that line. Bulkheads above the window, common in new builds and over doors, can force a face fit and change where your top fixing lands.
The surface behind the bracket, timber, brick, or gyprock (plasterboard), changes where your fixings can safely go, and that can shift your measurements. Gyprock is the catch: it won't reliably hold a screw on its own, so the blind needs its fixings landed on the solid timber studs or noggins behind the plasterboard. Knowing the wall, and knowing where the solid fixing points sit behind it, is part of measuring a blind that stays put for years.
Because we're a shop-at-home service, measuring is something we do for you, free, before you commit to anything. A consultant comes to your home, measures every window properly, checks what's in the way and what you're fixing into, and recommends reveal or face fit based on what each room is actually for. The measurements, and the responsibility for getting them right, sit with us.
With a DIY order, a mistake is yours to live with and yours to pay for, because a made-to-measure blind can't be resized. With an in-home measure, if a window's tricky, we catch it on the day. Once you have your measurements, see how to install a roller blind.
Decide reveal fit or face fit first, it changes how every measurement is taken.
Measure width and drop in millimetres; measure the width in several places and use the narrowest reading for a reveal fit.
The common mistakes are clerical (mm vs cm, dropped 100mm) and missed obstructions (handles, mullions, bulkheads, skirting, tiles).
What you fix into matters, gyprock needs fixings on solid studs, which can affect bracket positions and measurements.
A single roller maxes out around 3,200mm; split wider spans rather than stretch them.
As a shop-at-home service, we measure free in your home, so the risk of a costly mistake is ours, not yours.
Measuring is the step where roller blinds most often go wrong, and it's the one part a DIY or online order can't take off your hands. Book your free measure and quote and we'll come to you, measure every window properly, check what's in the way, and make sure you get the right fit for each room.
Decide first whether the blind will sit inside the recess (reveal fit) or on the wall over the opening (face fit), because the two are measured differently. Then measure the width and drop in millimetres, measuring the width in several places and using the narrowest reading for a reveal fit, since openings are rarely perfectly square.
It depends on the fit. For a reveal fit you measure to the inside of the recess and the blind is made slightly smaller so it can operate. For a face fit you measure the opening plus an overlap on each side and the top, so the blind covers the window and the side gaps. Bedrooms usually suit a face fit for better light control.
Always millimetres. Mixing up centimetres and millimetres is one of the most common measuring mistakes, and because a roller blind is made to your exact measurement, the error can't be fixed afterwards.
Because window openings are rarely perfectly square, reveals bow and plaster is uneven, so the width can vary by several millimetres top to bottom. For a reveal fit the blind must clear the tightest point, so measuring in several places and using the narrowest figure stops the blind from scraping or jamming.
A single roller blind goes up to around 3,200mm wide, limited by fabric width. For wider openings, the better approach is to split the span into two or more blinds rather than force one oversized blind.
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