How to Measure for Blinds
Measuring for blinds sounds simple enough - until you're standing at the window with a tape measure, wondering where exactly you're supposed to start.
Inside the recess? Outside it? Top of the frame or top of the wall? It's one of those tasks that feels straightforward until it isn't, and getting it slightly wrong can affect both how the blind looks and how well it functions.
Here's a clear, practical guide to getting it right.
Recess Fit or Face Fit — Decide This First
Before you measure anything, you need to know where your blind will sit.
A recess fit sits inside the window frame. It gives a clean, tailored finish that works well in most spaces, particularly where you want the architecture of the window to remain visible. It does require precise measuring, because there's less room for error.
A face fit sits outside the recess, fixed to the wall or frame above the window and overlapping on all sides. It's a better choice for blocking light, and it's also more forgiving if your recess is shallow, uneven, or awkward in any way.
If you're not sure which to go for, a recess fit is usually the default so you can add other window treatments but it's worth thinking about what you want the window to do visually before you decide.
Measuring for a Recess Fit
Walls are rarely perfectly square, and windows are no exception. Take six measurements and always use the smallest figure — it's what ensures the blind fits without catching or scratching.
- Measure the width at the top, middle, and bottom of the recess
- Measure the drop on the left, centre, and right
- Always use the smallest figure for each
- Measure carefully at the exact point where the blind will be fitted — taking into account any vents, tiling, dado rails, or other obstructions
- The simplest way to think about it: the blind needs to move up and down smoothly, and that's what you're checking for
Measuring for a Face Fit
A face fit gives you more flexibility than a recess fit, but it still needs to be thought through carefully. You're deciding not just on size, but on how much of the wall and frame you want the blind to cover.
- Measure the full width of the window opening, from one side of the frame to the other
- Add a minimum of 5cm each side — 8–10cm is better for light blocking
- If you have coving or a ceiling detail, measure down from the same fixed point on each window — this keeps the top of every blind at the same visual height across the room, which matters more than you'd think
- Measure the drop from where you want the blind to sit above the window down to your desired length
- Allow 10–15cm above the window opening so the blind can stack neatly when open and doesn't block light when raised — this also covers the top of the window reveal for a cleaner, more finished look. As a guide, a Roman blind typically stacks between 25–30cm, so factor that into your drop measurement when deciding how high to fix the blind
- Window sills are rarely perfectly level — if yours is uneven, consider dropping the blind slightly below the sill rather than trying to sit it flush. It's a cleaner finish and avoids the blind catching
- If fitting above a radiator, measure to just below the window board rather than to the floor
Check for Obstructions Before You Finalise
Window handles, radiators, tiled sills, and window boards can all affect how a blind sits and operates. It's worth walking through this before you commit to any measurements, rather than discovering the issue once everything has been ordered.
Roll direction is worth thinking about here too — and it's one of those details that's easy to overlook until the blind is up.
If you have projecting window handles, a reverse roll is usually the better choice. Because the fabric hangs away from the wall into the room, it clears the handle rather than sitting against it and catching every time the blind is raised or lowered.
If blackout is the priority — particularly on a face fit — a regular roll is more effective. The fabric sits closer to the wall and the window, reducing the gap around the edges where light tends to creep in.
If you have tiling or mouldings around a sink or basin that sits within the window reveal, the blind will need to be narrower to clear them. In that case, a cassette or pelmet is worth considering — it gives a neat finish and conceals the mechanism where the blind can't sit flush to the frame.
It's a small decision, but it makes a real difference to how the blind performs day to day.
Consider How the Blind Will Work in the Room
This part tends to get left out of measuring guides, but it matters.
Think about whether you need light filtering or blackout. Whether the blind will sit alone or alongside curtains. Whether this is a purely practical window — a bathroom, a utility room — or somewhere the finish needs to earn its place.
The measuring is technical. The decision about which blind to choose is visual, and it's worth giving it equal thought.
When It's Worth Getting Help
Bay windows, uneven reveals, floor-to-ceiling glazing, and tight recesses are all situations where a professional measure is genuinely useful. Blinds are one of those things where a few millimetres off can be noticeable — and it's a difficult thing to correct after the fact.
Measuring isn't complicated, but it does need care and a little patience. If you find yourself second-guessing the numbers, it's usually worth pausing before placing an order.
If you'd like a second opinion, we're always happy to help — get in touch and we can talk it through before anything is committed to.
Not sure where to start with the wider room?
If the blind is just one piece of a bigger picture, our Room Story Planner can help you find your direction before making any decisions. It's a good place to begin if you're thinking about how light, fabric and finish work together across a space — rather than treating each window in isolation.
