How to Measure for Blinds – The Complete Guide

Getting accurate measurements is the most important step when ordering made-to-measure blinds in Ireland. Unlike off-the-shelf blinds, our products are manufactured to your exact specifications – which means if your measurements are wrong, your blind won’t fit. The good news is that measuring your windows is straightforward when you know what to do. This guide walks you through how to measure blinds for every product type we supply, including roller blinds, venetian blinds, roman blinds, day and night blinds, composite doors, and uPVC windows.

Still unsure? Dublin Blinds also offers a free professional measuring service across Dublin and the surrounding counties. Contact us today to book an appointment.

What You Will Need

Before you start measuring, have the following to hand:

• Steel tape measure – essential for accuracy. Avoid fabric or soft tape measures, which can stretch and give inaccurate readings.
• Pencil and notepad – record each measurement immediately; don’t rely on memory.
• Step ladder – for high windows or mezzanine-level rooms.
• Assistant – a second pair of hands makes measuring wide windows much easier.

Important: Always measure in millimetres (mm). Our order forms and manufacturing processes use millimetres, so quoting in centimetres or inches can lead to errors.

Recess Fitting vs. Face Fitting – Understanding the Difference

Before measuring, you need to decide how your blind will be fitted. This is known as the fitting type, and it affects how you take your measurements.

Recess Fitting (Inside Mount)

The blind is fitted inside the window reveal, sitting within the recess. This is the most common fitting in Irish homes and gives a clean, tailored look. For recess fitting:

• The blind sits within the window opening.
• Deduct 10mm from the actual recess width to allow clearance for brackets and smooth operation.
• Measure the full height of the recess for the drop.
• Requires a minimum recess depth of approximately 50-70mm depending on blind type.

Face Fitting (Outside Mount)

The blind is fitted outside the window recess, mounted on the wall or onto the window frame surround. This is ideal when the recess is too shallow, when you want to maximise the amount of light blocked, or when you prefer a bolder look. For face fitting:

• Add at least 75mm overlap on each side of the window opening to block light effectively.
• Add at least 100mm above the top of the window opening for the headrail.
• Measure the drop from where the bracket will be fixed down to the required finish point.

How to Measure for Roller Blinds

Roller blinds are one of the most popular window coverings in Ireland. Their clean, minimalist profile makes them easy to measure and fit. Here is how to measure for roller blinds in both recess and face-fitting scenarios.

Roller Blinds – Recess Fitting

1. Width: Measure the inside width of the recess at three points – top, middle, and bottom. Use the smallest measurement. Deduct 10mm from this figure to allow for the brackets on each side. This is your order width.
2. Drop: Measure from the very top of the recess to the window sill. This is your order drop. If you have a deep reveal and want the blind to sit as close to the glass as possible, measure from the intended bracket fixing point down to the sill and add the headrail height (usually 30-40mm).

Example: Recess width 900mm → Deduct 10mm → Order width: 890mm. Recess drop 1,200mm → Order drop: 1,200mm.

Roller Blinds – Face Fitting

1. Width: Measure the full width you want the blind to cover. Add a minimum of 75mm overlap on each side of the window opening. This is your order width.
2. Drop: Measure from where the top of the bracket will be fixed (above the window) down to the lowest point you want the blind to reach (sill or 50mm below sill for a fuller drop).

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How to Measure for Venetian Blinds

Venetian blinds – available in real wood, faux wood, and aluminium – require slightly more precision due to their rigid slat construction. It is especially important to measure for recess depth before ordering.

Recess Depth Check for Venetian Blinds

Before measuring width and drop, check that your window recess is deep enough to accommodate the headrail and tilted slats:

• Aluminium venetian blinds (25mm slats): Minimum recess depth of 55mm required.
• Wooden venetian blinds (50mm slats): Minimum recess depth of 65mm required.
• Faux wood venetian blinds (50mm slats): Minimum recess depth of 65mm required.

If your recess is shallower, opt for face fitting.

Venetian Blinds – Recess Fitting

1. Width: Measure the inside width of the recess at top, middle, and bottom. Use the smallest reading. Deduct 10mm. This is your order width.
2. Drop: Measure from the top of the recess to the window sill. Deduct 10mm to prevent the bottom rail resting on the sill (which causes binding and wear). This is your order drop.

Venetian Blinds – Face Fitting

1. Width: Add 75mm to each side of the window opening for overlap.
2. Drop: Measure from the top bracket position to your required finish point. The blind will hang 30-40mm below the bottom rail, so account for this if fitting above a sill.

Browse our full range of venetian blinds

How to Measure for Roman Blinds

Roman blinds create an elegant, tailored appearance with their soft fabric folds. Because the fabric piles up at the top when raised, face fitting is often recommended for roman blinds if you need maximum window clearance when the blind is open.

Roman Blinds – Recess Fitting

1. Width: Measure the inside width of the recess at three points. Use the smallest measurement. Deduct 20mm (to allow 10mm clearance on each side, as roman blind fabric is wider than the headrail). This is your order width.
2. Drop: Measure from the top of the recess to the window sill. For a neater finish, deduct 10mm so the blind clears the sill. This is your order drop.

Roman Blinds – Face Fitting

1. Width: Add a minimum of 100mm overlap on each side of the window opening (total addition of 200mm to the window opening width). This blocks more light and gives a more generous, luxurious appearance.
2. Drop: Measure from the intended bracket fixing point to the required finish point. Fix the bracket at least 100mm above the window opening to allow the fabric folds to clear the glass when the blind is raised.

Tip: For north-facing rooms or rooms requiring good light control, always choose face fitting for roman blinds and maximise the overlap.

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How to Measure for Day & Night Blinds

Day and night blinds (also called zebra or vision blinds) feature alternating sheer and opaque fabric bands. Because the operating mechanism requires slightly more clearance than a standard roller blind, the measuring process includes one additional consideration.

Recess Depth Check for Day & Night Blinds

Day and night blinds require a minimum recess depth of 60mm for the cassette headrail. If your recess is shallower, you must use face fitting.

Day & Night Blinds – Recess Fitting

1. Width: Measure the inside width of the recess at top, middle, and bottom. Use the smallest reading. Deduct 10mm for clearance. This is your order width.
2. Drop: Measure from the top of the recess to the window sill. This is your order drop. Note: the sheer bands will remain visible even when the blind is fully ‘closed’, offering privacy while maintaining some natural light.

Day & Night Blinds – Face Fitting

1. Width: Add 75-100mm to each side of the window opening. The wider the overlap, the better the light blocking when the opaque bands are aligned.
2. Drop: Measure from your intended bracket position to the required finish. Allow 50-100mm above the window opening for the headrail cassette.

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How to Measure for Composite Doors

Whether you are replacing an existing door or fitting a new composite door into a newly built frame, accurate measurements are critical. A composite door is a significant investment, and incorrect measurements can result in costly delays. Our team recommends letting our fitting professionals carry out a full site survey before any composite door order is placed.

Measuring an Existing Door Opening

1. Width: Measure the width of the existing door opening (inside the frame) at three heights – top, middle, and bottom. Use the smallest measurement.
2. Height: Measure the clear height of the door opening (inside the frame) from the floor (or threshold) to the top of the frame at three points – left side, centre, and right side. Use the smallest measurement.
3. Frame depth: Measure the depth of the existing frame at the reveal to confirm that a standard frame will suit your wall thickness. Most Irish homes have reveals of 150-200mm, and we supply frames to suit.
4. Handing: Note whether the door is left-handed or right-handed. Stand outside facing the door: if the handle is on the right and the hinges are on the left, it is left-handed; if the handle is on the left and hinges are on the right, it is right-handed.
5. Inward or Outward Opening: Note whether the existing door opens inward (into the house) or outward. The vast majority of Irish front doors open inward.

Composite Door – Key Measurements Summary

We strongly recommend a free professional site survey for all composite door orders. Book your free survey today.

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How to Measure for uPVC Windows

Measuring for replacement uPVC windows is a more involved process than measuring for blinds. Wall thickness, reveal depth, lintel positions, and existing frame conditions all need to be assessed. As with composite doors, Dublin Blinds always recommends a professional survey before any window order is confirmed.

Replace-in-Frame vs. Full Frame Replacement

Before taking measurements, establish whether you are doing a replace-in-frame installation (the new window is inserted into the existing outer frame) or a full frame replacement (the entire existing frame is removed and a new frame is fitted into the masonry opening).

• Replace-in-frame: Measure the inner visible opening of the existing frame at top, middle, and bottom for width, and at left, centre, and right for height. Deduct 10mm from each dimension to allow for fitting clearance.
• Full frame replacement: Measure the masonry opening (the complete hole in the wall) at multiple points. Our surveyor will assess lintel, sill, and reveal condition during the site visit.

uPVC Window – Key Measurements Summary

All uPVC window orders include a free professional site survey. Request your free survey today.

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Top 5 Measuring Mistakes to Avoid

Even experienced DIYers make these common errors. Avoid them to ensure your first order is correct:

1. Using a fabric tape measure. Fabric tapes stretch over time and can give readings that are several millimetres off – enough to cause fitting problems. Always use a rigid steel tape measure.
2. Measuring in centimetres or inches. All our products are manufactured in millimetres. Submitting measurements in other units causes confusion and potential errors. Measure and record in mm only.
3. Only measuring at one point. Window openings are rarely perfectly square, especially in older Irish homes. Always measure width at three heights and height at three widths, and use the smallest reading each time.
4. Forgetting the deduction for recess fitting. If you order a blind at the exact recess width, it will not fit. Always deduct 10mm for roller, day & night, and venetian blinds; and 20mm for roman blinds.
5. Not checking recess depth. A beautiful venetian or day & night blind will not fit if your recess is too shallow for the headrail. Check the minimum depth requirements before choosing recess fitting.

How to Measure for Blinds

Measuring FAQs

Ready to Order? Let Us Help.

Now that you know how to measure for blinds, you are ready to browse our full collection and place your order with confidence. If you have any questions about measuring or need professional help, our friendly team is always happy to assist.