The Ultimate Guide to Measuring Your Windows for Blinds and Shades So, you're ready to transform your living space with beautiful new blinds or shades! That's fantastic. However, before you dive into choosing colours and styles, there's one crucial step you absolutely cannot skip: accurate window measurement. Getting this right is the foundation for perfectly fitting window treatments that look stunning and function flawlessly. At Blinds Concept, we understand that measuring can feel a little daunting.
That's why we've put together this comprehensive, step-by-step guide to walk you through every scenario, from standard windows to tricky architectural features. Grab your trusty steel tape measure, a pen, and our handy worksheet, and let's get started! Why is accurate measurement so important? Perfect Fit: Ill-fitting blinds look unprofessional and can detract from your efforts to create a beautiful home. Too narrow, and you'll have light gaps. Too wide, and they won't fit at all.
Optimal Light Control & Privacy: Precise measurements ensure your blinds provide the light control and privacy you desire. Smooth Operation: Properly sized blinds operate smoothly without snagging or struggling. Cost Savings: Avoiding mistakes means avoiding costly re-orders and wasted time. Enhanced Aesthetics: Custom-fit window treatments elevate the entire look of your room. Before You Begin: Essential Tools & Tips You don't need a lot, but what you do need should be reliable: Steel Tape Measure: Crucially, this must be a steel tape measure.
Cloth or retractable fabric ones can stretch and give inaccurate readings. Pen or Pencil: To jot down your measurements. Paper/Worksheet: We've provided one below, or you can create your own. Step Ladder (if needed): For high windows, safety first! A Friend (optional but helpful): An extra pair of hands can make things easier, especially for large windows. Phone/Camera: Take photos of your windows, especially if they have unique features. This can be helpful when discussing your order.
Key Measurement Tips: Measure Twice (or Thrice!): This isn't just a saying; it's a golden rule for window treatments. Re-measure to confirm accuracy. Always Use Millimetres or Centimetres for Precision (or Inches to the Nearest 1/8"): We recommend measuring in metric for the ultimate precision. If using inches, always measure to the nearest 1/8th of an inch. Provide the EXACT Measurement: Do not make deductions! Our manufacturers will make the necessary deductions or additions based on whether you choose an inside or outside mount and the specific product type.
Giving us the exact window opening (for inside mount) or desired finished size (for outside mount) is critical. Specify Inside vs. Outside Mount: Clearly indicate for each window whether the measurement is for an inside mount or an outside mount. Label Each Window: Assign a unique name or number to each window you measure (e.g., "Living Room North Window," "Bedroom 1 West Window"). This prevents confusion. Understanding Mount Types: Inside vs.
Outside The first decision you need to make for each window is whether your blinds or shades will be mounted inside the window frame recess or outside the frame, on the wall or trim. Inside Mount What it is: Your window treatment fits snugly within the window frame opening, creating a clean, integrated look. The frame itself acts as a natural border for the blind. Ideal for: Showcasing beautiful window trim. Situations where you want the blinds to be less prominent. French doors or areas where protruding blinds might interfere with door handles or room flow.
Windows with deep sills you want to keep clear. Considerations: Requires a minimum window frame depth (we'll check for this). May allow for small light gaps around the edges. Outside Mount What it is: Your window treatment is mounted on the wall or window trim around the window opening, extending beyond the frame. This allows for maximum light blockage and privacy, as the blind overlaps the window opening. Ideal for: Shallow window frames where an inside mount isn't possible. Covering an entire window and its trim for a more dramatic look.
Maximizing light blockage and privacy (room darkening, blackout blinds). Making a window appear larger. Covering inconsistencies in window frame squareness. Considerations: Means the blind will project further into the room. Requires sufficient flat mounting surface around the window. Step-by-Step Measurement Guide 1. Measuring for Inside Mount Blinds and Shades For an inside mount, you are measuring the exact dimensions of the window opening into which the blind will fit. Crucially, DO NOT make any deductions yourself; the manufacturer will handle this for a perfect fit.
Provide us with the exact opening size. Step 1: Measure the Width Measure the inside width of your window opening in three different places: Top: From the inside edge of the frame to the opposite inside edge, right at the top. Middle: Repeat the measurement across the centre of the window. Bottom: Repeat the measurement across the bottom of the window. Record the NARROWEST of these three measurements. This ensures your blind will fit even if your window isn't perfectly square. Example: Top: 91.5 cm (36" - 1/8"), Middle: 91.3 cm (36" - 1/16"), Bottom: 91.4 cm (36" - 1/8").
You would record 91.3 cm (36" - 1/16") as your width. Step 2: Measure the Height Measure the inside height of your window opening in three different places: Left: From the top inside edge of the frame to the bottom inside edge, on the left side. Centre: Repeat the measurement in the middle of the window opening. Right: Repeat the measurement on the right side of the window opening. Record the LONGEST of these three measurements. This ensures your blind will cover the entire height of the window, even if it's slightly uneven.
Example: Left: 122.0 cm (48" - 1/8"), Centre: 122.1 cm (48" - 1/4"), Right: 121.9 cm (48"). You would record 122.1 cm (48" - 1/4") as your height. Step 3: Check the Depth of Your Window Frame This is vital for inside mount to ensure there's enough room for the blind headrail to be mounted flush with the window frame. Take your tape measure and measure the depth from the window glass to the front edge of the window moulding (or to wherever you want the blinds to sit).
Required Depth: The minimum depth varies significantly by product: Roller Shades: Typically 4 cm to 6 cm (1.5" to 2.5") depending on the roll size and bracket. Cellular/Honeycomb Shades: Around 3 cm to 5 cm (1.25" to 2") for flush mount. Faux Wood/Wood Blinds: 5 cm to 7 cm (2" to 2.75") for flush mount. Vertical Blinds: 6 cm to 8 cm (2.5" to 3.25"). If your window frame depth is less than the required amount for a flush inside mount, the headrail may protrude slightly, or you might need to consider an outside mount. Consult with us if you're unsure!
Step 4: Check for Obstructions Look for anything that might prevent the blind from operating freely: Window Crank Handles: Ensure there's clearance for handles, especially for roller or cellular shades. Latches or Locks: Will the blind clear these when fully raised or lowered? Alarms: Are there any alarm sensors on the window frame that the blind might interfere with? If obstructions exist, measure their protrusion. You might need to order "projection brackets" or consider an outside mount. 2.
Measuring for Outside Mount Blinds and Shades For an outside mount, you are measuring the exact dimensions of the blind or shade you want, including any overlap beyond the window opening. This means you need to add your desired overlap to the window opening dimensions. The manufacturer will NOT make deductions; they will produce the blind to the exact measurements you provide. Step 1: Determine Your Desired Coverage (Width) First, measure the actual width of your window opening (from inside edge to inside edge of the trim).
Then, decide how much you want the blind to overlap the window opening on each side. A common overlap is 5 cm to 10 cm (2" to 4") on each side, though often 7.5 cm (3") per side is a good starting point for optimal light coverage. Calculation for Width: Actual Window Opening Width + Desired Overlap Left Side + Desired Overlap Right Side = Total Finished Blind Width Example: Window opening is 91.5 cm (36"). You want 7.5 cm (3") overlap on each side. 91.5 cm + 7.5 cm + 7.5 cm = 106.5 cm (36" + 3" + 3" = 42"). Record 106.5 cm (42") as your width.
Measurement Tip: Instead of calculating, you can hold your tape measure up directly to the wall and mark your desired left and right edges. Then, measure the distance between those two marks. This can be easier for some! Step 2: Determine Your Desired Coverage (Height) First, measure the actual height of your window opening (from inside edge to inside edge of the trim). Then, decide how much you want the blind to overlap the window opening at the top and bottom.
A common overlap is 5 cm to 10 cm (2" to 4") at the top and 5 cm (2") at the bottom, or letting it extend to the window sill if you prefer. For maximum light blockage, overlapping well above the top of the window trim is recommended. Calculation for Height: Actual Window Opening Height + Desired Overlap Top + Desired Overlap Bottom = Total Finished Blind Height Example: Window opening is 122.0 cm (48"). You choose 10 cm (4") overlap at the top and 5 cm (2") overlap at the bottom. 122.0 cm + 10 cm + 5 cm = 137.0 cm (48" + 4" + 2" = 54"). Record 137.0 cm (54") as your height.
Measurement Tip: Just like width, you can mark your desired top and bottom mounting points on the wall and measure the distance between them. Step 3: Consider Mounting Location and Space (Header Height) You'll need a flat, unobstructed surface at the top above your window for the headrail brackets. Measure this space to ensure there's enough room. Above Trim: Measure the flat space available above your window trim. Sufficient Space: Most headrails for blinds and shades require 2.5 cm to 5 cm (1" to 2") of flat space above the window for secure mounting.
Ensure there are no permanent fixtures (like light fixtures or crown moulding) that will interfere. Step 4: Check for Obstructions (Wall/Trim) Ensure there are no obstructions on the wall or trim where the blind will hang, such as light fixtures, decorative moulding, or alarm sensors, that would prevent the blind from falling straight or operating properly. Special Window Measurement Situations Sometimes, a window isn't just a simple rectangle. Here's how to tackle common special situations: 1.
Bay Windows & Corner Windows Measuring for bay windows requires careful attention to angles and depths to ensure blinds don't collide when operated. The goal is to achieve minimal light gaps while allowing each blind to function independently. Key Principle: Overlap at the Corners (or gap for clearance) Blinds for bay windows are often installed with a small overlap at the corner where two windows meet, or with a small gap to ensure clearance. Sketch Your Bay Window: Draw a simple top-down diagram of your bay window, numbering each section (e.g., Left, Centre, Right).
Decide on Mount Type: Inside mount is most common for bay windows to preserve the architectural feature. Measure Each Section Individually (Inside Mount): Width: For each section, measure the width at the top, middle, and bottom. Record the narrowest measurement. Height: For each section, measure the height at the left, centre, and right. Record the longest measurement. Measure Depth: Check the depth of each window frame section. Measure Corner-to-Corner Gaps (Crucial!): Measure the distance from the point where the left blind will end to the point where the centre blind will begin.
Repeat for the centre to the right blind. Why this matters: Manufacturers need to know if they need to make additional deductions for end caps or if a small positive overlap is desired. Standard deductions are usually made to prevent collision, but exact measurements help. Identify Obstructions: Are there window cranks or latches at the corner where the blinds meet? Note their position and protrusion. Recommendation: For bay windows, especially if you're feeling less confident, we strongly recommend a professional measurement consultation . 2.
French Doors & Sliding Patio Doors The main challenge here is dealing with door handles that protrude, and ensuring the blinds don't interfere with the door's operation or get damaged. For French Doors (generally inside mount, sometimes shallow outside mount): Measure Each Door Window Individually: Treat each glass pane as a separate window. Width: Measure width at top, middle, and bottom of the glass recess. Record narrowest. Height: Measure height at left, centre, and right of the glass recess. Record longest.
Obstruction Check (Handles!): Measure Handle Depth: Determine how far the door handle projects from the surface of the door. Measure Handle Height: From top or bottom of the glass opening to the top/bottom of the handle. Choose Slim Profile Blinds: Cellular/Honeycomb shades, especially top-down/bottom-up, or thin roller shades are excellent choices. Hold Down Brackets (Optional): These are small clips at the bottom of the blinds that keep them from flapping against the door when it opens and closes. If you want these, ensure you have a flat surface on the bottom of the door frame.
Mount Type: Often, an inside mount is preferred for a clean look, or a very shallow outside mount directly onto the door surface, allowing clearance for handles. For Sliding Patio Doors (usually outside mount): Outside Mount Preferred: Typically, vertical blinds, panel tracks, or large roller shades are used for sliding doors, mounted on the wall above and beside the door frame. This allows the blind to stack off the glass, maximizing the opening. Width: Measure the total width including all door panels & any trim you want to cover.
Add your desired overlap on each side (e.g., 10-15 cm / 4-6" per side) for better light blockage and stacking space. Height: Measure from where you want to mount (typically 5-10 cm / 2-4" above the door frame) down to the floor or just above any sill/threshold. Stacking Room: Consider which direction your door slides. You'll want enough wall space on that side for the blind to completely clear the glass when open. 3. Arched Windows Arched windows are beautiful architectural features that require specialized treatment.
Key Principle: Specialized Shapes These often require custom-shaped treatments like specialty cellular shades or sunburst shutters that are built to fit the curve. Width: Measure the width at the widest point of the arch (usually just before the curve begins). Height (Legs): Measure the vertical height from the base of the window to the point where the curve starts, on both the left and right sides. Height (Apex): Measure the total vertical height from the base of the window to the very top (apex) of the arch. Depth Check: Ensure sufficient depth for mounting brackets.
Recommendation: For arched windows, professional measurement is highly recommended, as these treatments are custom-fabricated to precise tolerances. Book a Consultation with Blinds Concept. 4. Skylights Skylights bring in wonderful light but can also introduce glare and heat. Measuring them correctly ensures the shades function reliably in an overhead position. Key Principle: Recessed Opening Skylight shades are almost always designed for an inside mount within the skylight frame.
Identify the Mount Surface: Shades for skylights are typically installed onto the frame or a surrounding drywall recess. Width: Measure the width of the opening at the nearest point where the shade will mount, top, middle, and bottom. Record the narrowest. Height/Length: Measure the length of the opening at the left, centre, and right. Record the longest. Depth: Measure the depth of the recess to ensure the mechanism can fit flush or recessed. Operational Type: Consider if you need a manual (with an extension pole) or motorized shade for ease of use.
Recommendation: Skylights can be tricky due to their overhead position and potential for obstructions. A professional measurement is a good idea here. Common Measurement Mistakes to Avoid Even the most careful DIYer can stumble. Watch out for these pitfalls: Not Using a Steel Tape Measure: Fabric tapes stretch, leading to inaccurate readings. Making Your Own Deductions for Inside Mounts: Always provide the exact window opening size; our manufacturers apply the correct deductions.
Forgetting to Add Overlap for Outside Mounts: You must account for how much wider and longer you want the blind than the window opening. Measuring Only Once: Always measure at least twice, preferably three times, for both width and height. Measuring at Only One Point: Windows are rarely perfectly square. Measuring at multiple points (top/mid/bottom for width, left/mid/right for height) is critical. Not Checking Depth for Inside Mounts: A shallow window frame can't accommodate a flush inside mount for many products.
Ignoring Obstructions: Window cranks, door handles, alarm sensors, or even nearby furniture can interfere with blind operation. Rounding Errors: Measure to the nearest 1/8" or millimetre for optimal precision. Avoid rounding to the nearest full inch or centimetre. Confusing Width and Height: It sounds obvious, but it's an easy mistake to make when recording! Always double-check which dimension is which. Not Labeling Windows Clearly: If you're ordering for multiple windows, confusing "Bathroom East" with "Bathroom West" can lead to big headaches.
When to Hire a Professional Measurer While we encourage you to use this guide, there are times when bringing in an expert is truly the best course of action: Complex Windows: Bay windows, arched windows, skylights, unusually shaped windows, or very large windows. Multiple Windows: If you're doing an entire home, the sheer volume can be overwhelming. High or Hard-to-Reach Windows: For safety reasons if a tall ladder is required. Expensive Custom Treatments: If you're investing in premium wood blinds or motorized shades, ensuring a perfect fit is paramount.
Uncertainty: If you feel at all unsure about any step of the measuring process. At Blinds Concept, we offer complimentary professional measurement services. Our experts will come to your home, take precise measurements, assess any unique challenges, and provide tailored recommendations. This eliminates guesswork and guarantees a perfect fit every time. Measurement Worksheet/Checklist Print this out and use it for each window!
Window Information: Window Location/Name: Product Interest (e.g., Roller Shade, Faux Wood Blind): Mount Type: [ ] Inside Mount [ ] Outside Mount For Inside Mount: Width Measurements: Top Width: cm / inches Middle Width: cm / inches Bottom Width: cm / inches RECORD NARROWEST WIDTH: cm / inches Height Measurements: Left Height: cm / inches Centre Height: cm / inches Right Height: cm / inches RECORD LONGEST HEIGHT: cm / inches Window Frame Depth: cm / inches (Glass to front of trim) Obstructions (handles, alarms, etc.)?
[ ] Yes [ ] No Details: For Outside Mount: Actual Window Opening Width (for reference): cm / inches Desired Overlap (each side): cm / inches Total Desired Finished Blind WIDTH: cm / inches Actual Window Opening Height (for reference): cm / inches Desired Overlap (top): cm / inches Desired Overlap (bottom): cm / inches Total Desired Finished Blind HEIGHT: cm / inches Flat Mounting Space Above Window: cm / inches Obstructions on Wall/Trim?
[ ] Yes [ ] No Details: Frequently Asked Questions (FAQ) Q: Do I measure inside or outside the window frame? A: It depends on the look and function you desire! Inside mount: Measure the exact window opening. This gives a clean, built-in look. Outside mount: Measure the desired finished size of the blind, including any overlap onto the wall or trim. This offers better light blockage and can make a window appear larger. Always indicate which mount type you're measuring for when placing your order. Q: How much extra width for outside mount shades?
A: For best light blockage and aesthetics, we generally recommend adding 5 cm to 10 cm (2" to 4") of overlap to each side of the window opening. So, if your window opening is 90 cm (35.5"), you might order a blind that is 100 cm to 110 cm (39.5" to 43.5") wide (adding 5-10 cm / 2-4" on each side). Q: What if my window isn't square? A: This is very common! For Inside Mount: Always record the narrowest width and the longest height. Our manufacturers will make the appropriate deductions to fit the smallest dimension, ensuring the blind fits without forcing.
This means there might be very tiny light gaps where the window is wider, but the blind will operate smoothly. For Outside Mount: This is an excellent solution for out-of-square windows, as the blind covers the entire opening and any imperfections of the frame. Simply measure the desired finished size of your blind, extending beyond the frame's irregularities. Q: How do I measure for motorized blinds? A: The measurement process for motorized blinds is exactly the same as for their manual counterparts (inside mount or outside mount). The key difference is often in power source considerations.