Decide whether the blind will sit inside the recess or on the wall around it, then measure the width and the drop in millimetres at three points each. For a recess fit you give the tightest measurement and let the maker take the clearances off. For a face fit you add overlap on each side and measure to where you want the vanes to finish.
Recess fit or face fit first
A recess fit puts the track inside the window reveal. It looks neat and leaves the architrave on show, but the reveal needs enough depth for the vanes to turn without hitting the glass, the handles or the winders.
A face fit puts the track on the wall or the frame above the opening, with the blind overlapping each side. It covers more, lets less light in at the edges and lets the stack sit off the glass, which is why most sliding doors are face fitted. There is more on the trade off in our guide to inside vs outside mount blinds.
Check the depth before anything else
This is the measurement people skip. When a vertical blind turns, each vane swings through half its width either side of the track, so the reveal has to be deep enough for that swing as well as the track itself.
Measure from the face of the glass, or from the front of any handle or winder that sticks out, to the front edge of the reveal. As a rough guide, the common 89mm vanes want around 100mm of clear depth and the wider 127mm vanes want closer to 140mm.
If you do not have that depth, a face fit is the answer. Forcing a recess fit means vanes that knock the winder every time you turn them.
Measuring inside a recess
Measure the width at the top, the middle and the bottom of the recess, and write down the smallest. Then measure the drop at the left, the centre and the right, and again keep the smallest.
Do not take anything off. Most makers want the exact tight size and take their own clearances at the factory, and if you deduct as well the blind ends up with gaps at both ends. Just mark the sizes clearly as recess measurements.
Brick reveals in older Sydney homes are rarely perfectly square. If your three drop measurements differ by more than a few millimetres, note all three, because the vanes all hang at the same length and will show the slope against an uneven sill.
Measuring for a face fit
For width, measure across the outside of the frame or architrave and add overlap on each side. Most people add somewhere between 50 and 100mm a side, and more on the stack side if the wall allows, so the bundle of vanes can sit beside the glass instead of on it.
For drop, decide where the track will go, usually a little above the frame, and measure down from there. On a window, finish below the sill or just past the bottom of the architrave. On a door, measure to the floor and the vanes get set to finish about 10 to 20mm above it.
Measure the floor height at both ends of a door. Older floors are often out of level, and a blind cut to the high end can drag at the low end.
Note what is around the opening
Write down anything the track or the stack could run into. Cornices close above the frame, an old curtain track, a split system head, light switches and power points beside the door, and handles that stick out all change where the blind can go.
Then mark which way you want the blind to stack and which side the controls should be on. On a sliding door the stack normally sits over the fixed panel, as explained in our guide to vertical blinds for sliding doors. On a window, think about which side you walk past and where the furniture sits.
Mistakes that cost the most
Width always goes first and drop second, and both in millimetres. Swapping them, or writing centimetres, is the classic way to end up with a blind that would only fit if the window were turned on its side.
Measuring the glass instead of the recess or the frame is the other common one. The glass is always smaller than the opening, so a blind made to it leaves a gap all the way round.
Why we measure anyway
Your measurements are useful for planning and for a rough idea before we visit. The blind itself is made from our own measure. Steve Bath measures every job himself and brings the samples, and he checks the depth, the handles and the floor while he is there.
Our verticals are made in our Sydney factory with the track cut to your opening, not the nearest stock width. That only works if the numbers are right, which is why we would rather take them ourselves.
Have a look at the vertical blinds range or the rest of our window blinds while you have the tape measure out. If you would rather skip the measuring altogether, Book a free measure and quote and we will do it as part of the visit.
Common questions
Do I measure the glass or the frame?
For a recess fit, it is neither. Measure the inside of the recess, wall to wall. For a face fit, measure across the outside of the frame or architrave and add overlap. The glass is always smaller than the opening, so measuring it leaves gaps.
How much overlap should a face fit vertical blind have?
Most face fit blinds overlap the opening by 50 to 100mm on each side. On the side the blind stacks to, extra width lets the stack sit on the wall instead of over the glass, as long as nothing is in the way.
How far off the floor should vertical blinds finish?
Usually 10 to 20mm. That is enough to stop the vanes dragging on carpet or catching a door track, without leaving an obvious strip of light along the floor.
Should I take deductions off a recess measurement?
No. Give the tightest recess size and say it is a recess measurement. The maker takes the clearances off, and if you deduct as well the finished blind will leave gaps at each end.
Is my window deep enough for a recess fit vertical blind?
Measure from the glass, or the front of any handle or winder, to the front of the reveal. Common 89mm vanes need roughly 100mm clear and wider vanes need more. Any shallower and a face fit is the better choice.