Measuring for Aluminium Venetian Blinds

Recess Fit (inside the window recess)

Measure the width of the recess at three points: the top, the middle, and the bottom. Record the narrowest measurement.
Measure the drop (height) of the recess at three points: the left, the centre, and the right. Record the longest measurement.
Allow a small clearance of approximately 10mm on each side to ensure the blind fits comfortably inside the recess without catching.
Check there are no obstructions such as window handles or tile edging that could prevent the blind from sitting flush.

Top Tip: Use a steel tape measure for accuracy. Fabric tape measures can stretch over time and give inaccurate readings.

Exact Fit (outside the window recess)

Measure the overall width you would like the blind to cover. We recommend adding at least 40mm on each side of the window recess to ensure good light coverage.
Measure the drop from where the brackets will be fixed to where you would like the blind to finish. Add an extra 40mm above the recess for the headrail and brackets.
Ensure the wall or frame area where brackets will be fixed is flat and unobstructed.

Important: When ordering an exact (face) fit, provide the exact overall measurements you require. The blind will be manufactured to these dimensions.

Helpful Hints

Always measure in millimetres for the most precise fit.
Double-check all measurements before ordering – blinds are made to measure and cannot be returned if measured incorrectly.
If your recess is not perfectly square, the recess fit with a small deduction is the safest option.

Measuring for Wood Venetian Blinds

Recess Fit (inside the window recess)

Measure the width of the recess at three points: top, middle, and bottom. Use the narrowest measurement.
Measure the drop at three points: left, centre, and right. Use the longest measurement.
Deduct 10mm from the width to allow clearance for the blind to raise and lower freely within the recess.
Ensure a minimum recess depth of 60mm to accommodate the headrail and stacked slats when the blind is fully raised.
Check for any window handles, locks, or keys that may obstruct the blind when it is lowered.

Top Tip: Wood venetian blinds have a larger stacking height than aluminium venetians. Ensure you have sufficient depth in the recess for the slats to stack neatly when raised.

Exact Fit (outside the window recess)

Measure the total width you want the blind to span. Add at least 50mm on each side of the window recess to block light effectively.
Measure the total drop from the intended bracket position to the desired bottom edge. Add 50mm above the recess for the headrail.
Ensure there is a flat mounting surface free of pipes, cables, or uneven plaster.

Important: Wood venetian blinds are heavier than aluminium. Ensure your fixings are suitable for the wall or frame type (e.g. use wall plugs for masonry, appropriate anchors for plasterboard).

Helpful Hints

Always measure in millimetres.
If you are unsure about the recess depth, an exact (face) fit mounted outside the recess is the safest option.
Check that the cord or wand mechanism will not interfere with furniture or radiators beneath the window.

Measuring for Roller Blinds

Recess Fit (inside the window recess)

Measure the width of the recess at three points: top, middle, and bottom. Use the narrowest measurement.
Measure the drop at three points: left, centre, and right. Use the longest measurement.
Deduct approximately 8mm from the width to allow smooth operation of the roller mechanism within the recess.
Ensure a minimum recess depth of 45mm so the rolled-up fabric does not protrude beyond the front of the recess.

Top Tip: Roller blinds have a small gap between the fabric edge and the recess wall on each side (typically 3–4mm). If total blackout is critical, consider an exact fit with overlap.

Exact Fit (outside the window recess)

Measure the total width you want the blind to cover. Add a minimum of 50mm on each side for good light coverage. For enhanced blackout, add 70mm on each side.
Measure the drop from the bracket mounting point to the desired bottom edge. Add 50mm above the recess for mounting the brackets.
Check that the area above the recess is flat and suitable for bracket installation.

Important: The fabric width of a roller blind is slightly narrower than the ordered width (typically 30–36mm less) due to the bracket and mechanism. Keep this in mind when calculating overlap.

Helpful Hints

Always measure in millimetres for accuracy.
Consider which side you want the chain or spring mechanism – this can usually be specified when ordering.
For bay windows, measure each section individually and order separate blinds for each.
If in doubt between recess and exact fit, exact fit gives more flexibility and better light blocking.

Measuring for Vertical Blinds

Recess Fit (inside the window recess)

Measure the width of the recess at three points: top, middle, and bottom. Use the narrowest measurement.
Measure the drop at three points: left, centre, and right. Use the shortest measurement so the louvres do not drag on the windowsill.
Deduct 10mm from the width to allow space for the headrail brackets and smooth operation.
Deduct 10mm from the drop to provide clearance between the louvre bottoms and the sill.
Ensure a minimum recess depth of 75mm to accommodate the headrail and louvre carriers.

Top Tip: When measuring for a vertical blind, always deduct from both width and drop. Unlike other blind types, vertical louvres hang below the headrail and can drag on the sill if the drop is too long.

Exact Fit (outside the window recess)

Measure the total width you want the blind to cover. Add 50mm–75mm on each side of the recess for light coverage.
Measure the drop from the bracket mounting position to the desired bottom edge. The blind should finish at least 15mm below the bottom of the window recess.
Ensure adequate clearance above the recess (at least 50mm) for the headrail and brackets.

Important: Vertical blind louvres rotate 180 degrees. Ensure no obstacles (such as protruding window handles or deep sills) will impede louvre rotation when the blind is open.

Helpful Hints

Always measure in millimetres.
Decide on the draw direction before ordering: left stack, right stack, or split (centre opening).
For patio doors and wide windows, vertical blinds are an excellent choice as they slide smoothly out of the way.
Vertical blinds can be trimmed slightly in height after installation if necessary, but not in width.

Measuring for Roman Blinds

Recess Fit (inside the window recess)

Measure the width of the recess at three points: top, middle, and bottom. Use the narrowest measurement.
Measure the drop at three points: left, centre, and right. Use the longest measurement.
Deduct 10mm from the width for clearance within the recess.
Ensure the recess depth is at least 55mm to accommodate the headrail and the folded fabric when the blind is fully raised.
Roman blinds have a significant stacking height when raised. For a small window, consider whether the stacked fabric will obscure too much of the glass.

Top Tip: Roman blinds fold into neat horizontal pleats when raised. A typical roman blind will stack approximately 250mm–350mm deep depending on the drop length. Account for this when deciding how much glass you want visible when the blind is up.

Exact Fit (outside the window recess)

Measure the total width you want the blind to span. Add at least 50mm on each side for good coverage and an attractive frame around the window.
Measure the drop from the bracket mounting point to your desired bottom edge. Add 100mm above the recess so the stacked fabric sits above the glass when the blind is fully raised.
Ensure the mounting surface is flat and level. Use a spirit level when installing the brackets.

Important: Roman blinds are heavier than roller blinds due to the horizontal battens and thicker fabric. Ensure your wall fixings are strong enough to support the weight, especially for wider blinds.

Helpful Hints

Always measure in millimetres.
Roman blinds look best when the folds are evenly spaced. This is handled during manufacturing, but providing accurate drop measurements helps achieve the best appearance.
Consider the fabric thickness and light-filtering properties when choosing your roman blind – lined fabrics provide better insulation and light blocking.
For bay windows, each section should be measured and ordered as a separate blind.

Measuring for Day & Night (Vision/Duo) Blinds

Recess Fit (inside the window recess)

Measure the width of the recess at three points: top, middle, and bottom. Use the narrowest measurement.
Measure the drop at three points: left, centre, and right. Use the longest measurement.
Deduct 8–10mm from the width for smooth operation of the dual-layer mechanism.
Ensure a minimum recess depth of 50mm to accommodate the cassette or open roller mechanism.

Top Tip: Day & Night blinds have two layers of fabric (alternating sheer and opaque bands) that align to filter or block light. Because the fabric passes around two rollers, the blind requires slightly more depth than a standard roller blind.

Exact Fit (outside the window recess)

Measure the total width you want the blind to cover. Add at least 50mm on each side for adequate light coverage.
Measure the drop from the mounting point to the desired bottom edge. Add 50mm above the recess for bracket clearance.
Ensure the mounting area is flat, level, and free of obstructions.

Important: The fabric width of a day & night blind is typically 25–35mm less than the ordered width due to the mechanism. Account for this when calculating the exact coverage you need.

Helpful Hints

Always measure in millimetres.
Day & night blinds work best on windows that are relatively square. If your window is significantly out of square, gaps may be more visible due to the dual-layer design.
The sheer sections allow natural light while maintaining privacy, making these an excellent choice for living rooms and bedrooms.
Choose a cassette (boxed) headrail for a sleeker finish if your recess depth allows it.

Measuring for Perfect Fit Blinds

How Perfect Fit Works

Perfect Fit blinds clip directly into the window frame beading – no drilling, no screws, no brackets. They are designed exclusively for uPVC (double or triple glazed) windows and doors. The blind sits within the glass area and moves with the window when opened or tilted.

Measuring Steps

Measure the visible glass width – this is the glass pane only, from the inside edge of the rubber seal (or glazing bead) on the left to the inside edge on the right.
Measure the visible glass height – from the inside edge of the rubber seal at the top to the inside edge at the bottom.
Measure the glazing bead depth – the depth of the frame bead from the front of the glass to the front of the bead. This must be a minimum of 18mm for the Perfect Fit frame to clip securely.
Check the bead shape – Perfect Fit blinds work with both square-edged and round-edged (chamfered) beading. Identify which type you have, as the clips differ.
Measure at three points for both width and height to account for manufacturing tolerances. Use the smallest width and the smallest height.

Top Tip: Do not include the glazing bead itself in your width and height measurements. Measure only the visible glass area. The Perfect Fit frame will sit on top of the bead.

Compatibility Check

uPVC frames only – Perfect Fit is not compatible with aluminium, timber, or composite frames.
Glazing bead depth must be at least 18mm.
Not suitable for windows where the bead has been sealed with silicone instead of mechanically clipped in.
Tilt-and-turn windows are compatible – the blind moves with the window.

Important: Incorrect measurements are the most common reason for Perfect Fit blinds not fitting. Take extra care to measure the glass area only and verify the bead depth before ordering.

Helpful Hints

Always measure in millimetres.
Perfect Fit is ideal for conservatories, tilt-and-turn windows, and French doors where drilling is impractical.
No tools are required for installation – the frame clips in and out by hand for easy cleaning.
If you have an older uPVC frame with non-standard beading, contact us with your bead measurements and we can advise on compatibility.

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LiteBlok™ Blackout Carbon Black

Blinds Price Calculator

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Why this colour

Key features

Installation

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Let us know what you think...

What others are saying

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Recess or exact fitting?

Recess Fitting

Exact Fitting

Recess or exact fitting?

Recess Fitting

Exact Fitting

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