When it comes to choosing vertical blinds, one of the most important — yet often overlooked — decisions is the slat width. The slats, also called blades, play a major role not just in how the blinds look, but also in how they perform. The two most common vertical blind blade sizes are 89mm and 127mm, and each offers unique advantages depending on the type of window, the look you want, and how much light or privacy you need.

Understanding the difference between these two blade sizes can help you choose the right vertical blinds for your space — whether you’re dressing a small bedroom window, a wide sliding door, or a bright sunroom. Let’s explore how 89mm and 127mm vertical blind blades compare, and how to decide which is best for your home or office.

Check out our Blinds by Room guide and Blinds by Window guide for expert advice on choosing the perfect window coverings for every space and window style in your home.

Understanding vertical blind blade sizes

Vertical blind blade sizes refer to the width of each individual slat that makes up the blind. The most common options are 89mm (approximately 3.5 inches) and 127mm (approximately 5 inches). While the difference might seem small, it can have a significant effect on how your blinds look and function.

The choice between these two sizes depends largely on window size, room design, and the amount of natural light and privacy you prefer. Smaller blades like 89mm create a contemporary, fine-lined appearance and are excellent for compact windows, while 127mm blades have a bold, classic presence that suits larger openings.

Both sizes can be customised in a wide range of fabrics, textures, and colours — from light-filtering materials to blockout fabrics — so the decision often comes down to aesthetics and proportions.

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89mm vertical blind blades

The 89mm vertical blind blade size is ideal for those who prefer a sleek, refined, and modern look. These slimmer slats are often used in residential interiors that favour minimalism or contemporary design.

Best for:

• Smaller or narrow windows: The narrower blades complement smaller spaces, helping windows appear taller and more elegant.
• Recess-fit installations: When blinds are installed inside the window frame, 89mm blades stack more compactly when open, allowing maximum visibility and keeping the frame clean and uncluttered.
• Greater privacy: Because there are more blades per blind, the overlap between slats provides enhanced privacy. Even when the blinds are tilted, the gaps are minimal, preventing clear visibility from outside.

From a design perspective, 89mm vertical blind blade sizes create fine vertical lines that visually elongate a room — perfect for enhancing height in areas with low ceilings. They also work well in offices, studies, and bathrooms where subtlety and privacy are priorities.

However, since there are more slats per blind, the overall appearance can feel a little “busier” on larger windows, and they may slightly restrict the view when the blinds are partially open.

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127mm vertical blind blades

The 127mm vertical blind blade size delivers a bolder, more traditional appearance. With their wider stance, these slats make a statement and are ideal for larger glass surfaces like sliding doors, picture windows, and bay windows.

Best for:

• Large windows and doors: The wider blades are better proportioned for big openings, ensuring the blind doesn’t look too crowded or cluttered.
• Unobstructed views: When drawn open, fewer slats mean a clearer, less obstructed view outside — ideal for spaces overlooking gardens, patios, or ocean views.
• Spacious installations: Because larger slats cover more area, fewer blades are needed, which simplifies the look and reduces the overall stack size when opened fully.

127mm vertical blind blade sizes are often chosen for open-plan living areas, sunrooms, and sliding doors that see frequent use. Their wide spacing between slats gives a clean, airy appearance when open and excellent light control when closed.

They also pair beautifully with high ceilings and expansive spaces, offering a balanced look that complements the scale of the room.

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Comparison: 89mm vs 127mm vertical blind blade sizes

Feature	89mm Blades	127mm Blades
Aesthetic	Sleek and modern	Broad and classic
Window size	Best for small or narrow windows	Best for large windows and sliding doors
View	Slightly more obstructed when open	Clearer view when open
Stack size	Smaller stack when pulled back	Wider stack when pulled back
Privacy	Better overlap, offering more privacy	Excellent privacy when closed, but less when tilted
Installation fit	Ideal for recess-fit installations	Best for face-fit installations over large areas

This comparison highlights that both blade sizes are effective — it’s really about matching proportions and priorities. If your focus is on privacy, tight stacking, and a modern aesthetic, go with 89mm blades. If you want larger-scale coverage, better outside views, and a classic look, 127mm blades are your best choice.

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Light control and energy efficiency

Regardless of size, both 89mm and 127mm vertical blind blade sizes provide excellent light control. Their rotating slats allow you to adjust sunlight levels precisely, helping to reduce glare while maintaining natural illumination.

Smaller 89mm slats offer tighter light-blocking properties due to the closer overlap, making them ideal for bedrooms or TV rooms. In contrast, 127mm slats allow a little more light diffusion when tilted, creating a soft, ambient glow that’s perfect for living and dining areas.

Both blade sizes can also contribute to energy efficiency. When closed, vertical blinds create a layer of insulation that helps regulate indoor temperature — keeping rooms cooler in summer and warmer in winter. Choosing a thicker or blockout fabric can further enhance these benefits.

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Style and design considerations

Choosing between the two vertical blind blade sizes also depends on your room’s interior design and overall aesthetic goals.

• Modern and minimal spaces: The clean, narrow lines of 89mm blades suit modern homes and offices with sleek furniture and subtle décor.
• Traditional or open-plan homes: The wider 127mm blades feel more balanced in larger rooms with generous windows or high ceilings.
• Fabric texture: Smooth or matte finishes look sharp and contemporary, while textured or woven fabrics add warmth and depth.
• Colour coordination: Lighter tones make a space feel open and airy, while darker shades create a bold focal point or contrast feature.

Vertical blinds are incredibly versatile and can be customised with curved tracks, pelmets, or chainless bottom weights for a cleaner finish — regardless of blade size.

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Choosing the right vertical blind blade size

Ultimately, the best vertical blind blade size comes down to proportion and purpose. For smaller windows, offices, and compact spaces, 89mm slats deliver a clean, unobtrusive look with excellent privacy. For wide openings like sliding doors or bay windows, 127mm slats provide strong visual balance, better outdoor visibility, and timeless appeal.

When installed correctly, both blade sizes offer durability, flexibility, and control — making them a reliable window furnishing solution for every type of room.

If you’re unsure which size suits your home best, consider how the blinds will function day to day. Do you need more privacy, or do you prioritise natural light and open views? Matching your lifestyle needs to the blade width will ensure you get the best results.

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Custom vertical blinds from The Blind Crew

At The Blind Crew, we specialise in custom vertical blinds designed to fit perfectly — whether you prefer the modern elegance of 89mm blades or the bold, classic style of 127mm blades. Our locally made blinds are built for durability, easy maintenance, and smooth operation, ensuring long-lasting performance.

We offer a wide range of fabrics, colours, and finishes to complement any interior style. Every blind is custom-measured and professionally installed to guarantee a perfect fit for your windows or doors. Whether it’s a small study, a sunroom, or a large sliding door, we can help you achieve the ideal look and functionality.

With The Blind Crew, you get expert advice, premium quality, and a finish that enhances your space — right down to the perfect blade size.