Short answer: the method is the same for blinds and shades, but shades are less forgiving on width and blackout shades need extra overlap to control light gaps.
What differs between blinds and shades
A blind has slats and a headrail. A shade is a continuous panel. That makes shades cleaner looking and slightly less tolerant of a crooked opening, because there are no slats to disguise a gap.
- Blinds hide small width errors better than shades do
- Roller and solar shades need the roll direction decided before ordering
- Cellular shades need clear depth for the headrail stack
- Blackout shades need overlap or a side channel, or light leaks at the edges
Measuring step by step
1. Decide inside or outside mount first
Everything downstream changes based on this. Inside mount sits within the frame and looks built in. Outside mount covers the opening and hides an out of square frame.
2. Measure the width in three places
Top, middle and bottom. Openings settle, especially in older houses. For an inside mount use the narrowest of the three. For an outside mount measure the area you want covered and add overlap on each side.
3. Measure the height in three places
Left, centre and right. For an inside mount use the longest. For an outside mount measure from where the treatment will mount to where you want it to end.
4. Check the depth
Inside mount needs enough clear depth for the headrail. Shutters need more than blinds. If the frame is shallow, or there is a crank, alarm sensor or tile return in the way, outside mount is the answer.
5. Write it width by height, always
Width first, height second, every time. Reversing them is the single most common way a custom order goes wrong.
The mistakes that cost a remake
- Measuring the old blind instead of the opening
- Rounding up on an inside mount, which leaves a treatment that will not fit
- Using one width measurement on an opening that is not square
- Forgetting the depth check before committing to inside mount
- Writing height before width
Light gaps, and what actually closes them
Every inside mount leaves a gap at the edges. It is physics, not a defect. If the room has to be genuinely dark, the options are an outside mount with overlap, side channels, or layering a drape over the shade.
Why custom orders punish small errors
A custom treatment is cut to the number you give. There is no returning it, no trimming it down and no swapping it for the next size. That is the whole reason we measure every opening ourselves rather than working from a list.
- An eighth of an inch too wide on an inside mount will not fit at all
- An eighth too narrow leaves a light gap you will notice every morning
- A height error shows as a treatment that stops short of the sill
- Reversing width and height produces something unusable
Openings are rarely square
Houses settle. Frames move. In most homes over a few years old, the width at the top of a window is not the width at the bottom, and the difference is often enough to matter on an inside mount.
This is why we measure in three places and why an outside mount is frequently the right answer in an older house, even when an inside mount would look neater.
Tools worth having
- A steel tape, not a cloth or fabric one, which stretches
- A step ladder, so you are measuring level rather than reaching
- A notepad with a column for width and a column for height, kept in that order
- A second person for anything wide or high
Or let us measure it
Every consultation includes measuring each opening on site. It is free, there is no obligation, and it removes the one risk that matters on a custom order: a treatment cut to the wrong number.
