How to Measure for Roller Blinds: Exact Step-by-Step

Accurate measurement is the single most important step in buying a made-to-measure roller blind. An incorrectly measured blind will not fit properly, will not operate correctly, and may not provide the light control or privacy you need. The good news is that measuring a window for a roller blind is a straightforward process — this guide takes you through every step, including the common pitfalls that catch out first-time buyers.

What You Will Need

Before you start, gather a steel measuring tape (fabric tapes stretch and are not reliable enough for this purpose), a pencil and paper, and a spirit level. Measure every window individually, even if they appear to be the same size — windows in older properties especially can vary by several millimetres, and that variation matters when ordering a made-to-measure blind.

Step 1: Decide on Inside Recess or Face Fix

Your first decision is whether to fit the blind inside the window recess (so it sits within the frame) or face-fixed on the wall or architrave above the window. This decision affects how you measure and what figures you give the supplier.

Inside recess fitting gives a clean, built-in appearance and is the most popular choice for modern interiors. Face fixing makes the window appear slightly larger, provides better light exclusion around the edges, and is the better choice when the recess is too shallow for the blind mechanism to sit comfortably inside it.

Inside Recess Measurement: Width

To measure the width for an inside recess fit, extend your tape from one side of the recess to the other at three points: at the top of the recess, at the middle, and at the bottom. Record all three measurements. If they differ — which is common, particularly in older properties — use the narrowest measurement. This ensures the blind will fit inside the recess without catching on the sides.

The blind supplier will typically deduct a small amount — usually 10 to 20 mm — from the width you provide in order to give the blind clearance inside the recess. Check the supplier's exact deduction before ordering so you are not surprised by a slightly narrower blind than expected.

Tip: Do not measure the existing blind if there is one already installed, as it may already have been made smaller than the recess. Always measure the recess itself.

Inside Recess Measurement: Drop

For the drop, measure from the top of the recess (where the bracket will be mounted) to the bottom of the recess at the window sill. Again, measure at three points — left side, centre, and right side — and use the longest measurement to ensure the blind reaches the full depth of the recess.

If you have a deep sill that extends into the room, you can choose to measure only to the top of the sill rather than to the bottom of the recess — this is a matter of personal preference based on how you want the blind to look when fully lowered.

Face Fix Measurement: Width

For a face-fixed blind, start with the width of the window opening (not the recess). Add at least 50 mm on each side of the window opening — so 100 mm to the total width. This overlap ensures that light cannot enter around the sides of the blind when it is lowered. For rooms where blackout performance is important, increase the side overlap to 75 or 100 mm on each side.

Bear in mind that the wider the blind, the more fabric there is to manage when it is fully raised. Very wide face-fixed blinds may produce a large fabric stack above the window when raised — consider whether this is aesthetically acceptable in your room.

Face Fix Measurement: Drop

For the drop of a face-fixed blind, decide how far above the window you want the head rail to sit. Mounting the head rail 50 to 100 mm above the top of the window opening makes the window appear taller and reduces the amount of light that enters at the top of the blind. Measure from the intended mounting point down to the sill or to the floor, depending on whether you want the blind to end at the sill or extend fully to the floor.

Face-fixed roller blinds that extend to the floor are increasingly popular in living rooms and home offices, particularly when paired with day and night blinds for a floor-to-ceiling effect. If this is the look you are going for, measure the full floor-to-ceiling height from the intended mounting point.

Checking for Obstacles

Before finalising your measurements, check for any obstacles within the recess or on the face of the wall that might impede the blind. Window handles are the most common culprit — if the handle protrudes into the recess, either the blind will need to be mounted above the handle's reach, or you will need to order the blind with a gap that allows the handle to operate freely.

Window winders, trickle vents, and secondary glazing frames can all also affect how and where the blind is mounted. Always measure with these obstacles in mind and note them when placing your order.

Recording and Ordering Your Measurements

Record your width and drop measurements clearly, specifying whether they are for inside recess or face fixing, and whether any deduction has been applied. When ordering from a made-to-measure blind supplier, provide the width and drop measurements in millimetres, confirm the fitting type, and note any obstacles or special requirements.

If you are ordering multiple blinds for the same room, measure each window individually and list the measurements separately, even if you expect the windows to be the same size. For any questions about measuring for a specific window type or configuration, the team at 1ClickBlinds is available to advise before you order.

What to Do if Your Measurements Are Wrong

If a made-to-measure blind arrives and does not fit correctly, the first step is to re-measure the window carefully and compare your new measurements with those you provided. If the error is on your side, most suppliers will offer a discounted replacement but may not be able to exchange a correctly made blind. This is why careful measurement — and double-checking before ordering — is so important.

If the blind has been made to the wrong size despite correct measurements being provided, contact the supplier's customer service team immediately with your original order confirmation and the measurements of the blind as delivered.