Measuring Windows for Shades and Blinds
Measuring Windows for Shades & Blinds
Follow this step-by-step playbook to capture precise widths, heights, and depths before ordering custom smart window treatments.
Quick Start Checklist
Work room by room and duplicate this list for every opening. Store each set of measurements in a labelled worksheet or spreadsheet.
- Decide whether the shade will sit inside the jamb (inside mount) or overlap the trim (outside mount).
- Inspect for obstructions — handles, locks, alarms, or tiles — and note anything that narrows the opening, then confirm at least 3–4 in (7.6–10 cm) of flat space above the window for outside-mount brackets.
- Measure width in at least three spots; record the smallest number and leave deductions to the factory.
- Measure height in three spots; use the tallest number for outside mounts and the shortest for inside mounts, adding extra headroom if the shade has a tall cassette or fold stack.
- Capture depth from the glass to the outermost obstruction so brackets and valances clear.
- Label each opening with the room name and orientation (e.g., “Primary Bedroom — Left Window”) and log notes in W × H × D order.
Tools You’ll Need
- Steel tape measure (25 ft or 8 m) — avoid fabric or laser-only devices.
- Small level or laser line for checking squareness.
- Pencil, painter’s tape, or digital note-taking app.
- Step stool or ladder for tall openings.
- Phone camera to capture each opening alongside your notes.
Pro move: log each measurement in width × height format (e.g., 35 7/8” × 64 1/4”) and include depth in a third column. Always jot width before height so your worksheet matches the order form.
Recording Your Numbers
- Start with width measurements at the top, middle, and bottom of the opening.
- Move to height from left, center, and right. Confirm sill slopes or tile lips.
- Note sill depth and any protruding locks, cranks, or alarm contacts.
- Mark control preference (left/right) and power access for motorized shades.
- Photograph each window with a sticky note showing the opening code to avoid mix-ups.
Never assume duplicate windows share sizes; measure every opening even within the same room.
Mounting Options at a Glance
Inside Mount
Sits fully within the jamb for a minimalist look and reveals surrounding trim.
- Use when trim is deep enough to house the headrail and brackets.
- Record the smallest width and shortest height; submit those exact numbers so the fabricator applies final deductions.
- If using side-mount brackets, mark “Side Mount” on your order so the factory adjusts the headrail width.
- Confirm depth clearance for valances, motors, or cassette fascias.
Outside Mount
Overlaps the frame to maximize blackout coverage and hide uneven jambs.
- Add 3-6 in (7.6-15.2 cm) to the total width to cover trim and minimize light gaps.
- Add 3-6 in to the height so the shade clears the sill or molding when raised.
- Use when the opening is out of square, shallow, or you need extra privacy, and ensure at least 3-4 in (7.6-10 cm) of flat surface above the window for brackets.
Standard Allowances & Deductions
| Scenario | Width Guidance | Height Guidance | Notes |
|---|---|---|---|
| Inside mount | Order the tightest opening width. | Order the shortest opening height. | The fabrication team deducts about 1/8 in (3 mm) in width for bracket clearance. |
| Outside mount | Add 3–6 in (7.6–15.2 cm) overall. | Add 3–6 in for stack clearance. | Overlap the trim or drywall for privacy and darker rooms; confirm at least 3–4 in (7.6–10 cm) of flat space for bracket mounting. |
| Fabric vs. valance width (roller, zebra) | Fabric arrives roughly 1 3/16 in (3 cm) narrower than the cassette. | No deduction. | Plan bracket placement so the narrower fabric still covers the glass. |
| Depth for deco bar / cassette | Minimum 1 3/4 in (4.5 cm); ideal 2 7/16 in (6.2 cm). | — | More depth keeps the fascia flush with the jamb. |
Pro Tip
Check for cranks, handles, alarms, or locks that project into the opening. Measure the narrowest point of the frame so the finished shade clears any hardware.
Shade-Specific Measuring Guides
Open each section for the product line you are ordering.
Roller & Solar Shades
Ideal for modern spaces and large expanses of glass. Account for the slimmer fabric width versus the cassette and leave room for the clutch or motor head.
Inside Mount
- Measure width at the top, center, and sill; use the smallest figure.
- Record height at three spots and use the shortest measurement so the shade clears the sill.
- Verify cassette depth: 2 in (5 cm) minimum for chain, 2 3/4 in (7 cm) for large motors.
Outside Mount
- Add at least 3 in (7.6 cm) to overall width; go wider for blackout fabrics.
- Mount 3–4 in (7.6–10 cm) above the opening to hide the roll and improve head clearance.
- Check for crown molding or valances that may require projection brackets.
Depth & clearance: Deco bar and cassette brackets need 1 3/4 in (4.5 cm) minimum. Aim for 2 7/16 in (6.2 cm) or more for a flush fit, and reserve about 4 in (10 cm) when stacking dual rollers in one cassette.
Zebra & Transitional Shades
Alternating sheers require precise alignment so the bands meet when closed. Double-check fabric deductions if pairing windows side by side and request the same dye lot so stripes line up across openings.
Inside Mount
- Record the tight opening width; the fabric ships about 1 3/16 in (3 cm) slimmer than the valance.
- Use the shortest height measurement and confirm sill levelness for smooth band alignment.
- Note which side houses the control to keep day/night bands consistent.
Outside Mount
- Extend width 4–6 in (10–15 cm) so the dual layers overlap the trim.
- Mount the cassette high enough that the shade clears window handles.
- Plan for spacer blocks if the wall surface is uneven or tiled.
Depth & clearance: Minimum inside depth 2 in (5 cm); 3 in (7.6 cm) recommended for motorization.
Cellular & Honeycomb Shades
Top-down bottom-up options add moving rails; measure carefully to keep both tracks square.
Inside Mount
- Measure width at three points and record the tightest number.
- For height, use the shortest measurement to eliminate drag on the sill.
- Confirm minimum depth: 1 1/2 in (3.8 cm) for standard rails, 2 1/4 in (5.7 cm) for cordless or motorized.
Outside Mount
- Add 3 in (7.6 cm) width on each side for premium blackout performance.
- Account for headrail stack height if mounting above a door or transom.
- Check for handles or mullions that could interfere with the bottom rail.
Depth & clearance: Target 2 3/4 in (7 cm) for flush headrail coverage.
Roman Shades
Elegant folds create stack height; plan for additional head space so the window clears when raised.
Inside Mount
- Measure width at top, middle, bottom; use the narrowest measurement.
- Use the shortest height; the fabrication team applies a slight deduction for clearance.
- Ensure opening is square to avoid fabric telescoping.
Outside Mount
- Add 5–8 in (12.7–20.3 cm) total width when aiming for blackout or wrapping wide trim.
- Mount 4 in (10 cm) above the casing so folds stack clear of the glass, and confirm 3–4 in (7.6–10 cm) of flat surface for the brackets.
- Note projections such as handles; spacer blocks keep fabric aligned.
Depth & clearance: Minimum 2 in (5 cm) for the headrail; 3 in (7.6 cm) preferred when adding a valance.
Bay & Corner Windows
Segmented bays demand individual measurements and careful planning so adjoining headrails clear one another.
- Measure each section (left, center, right) separately to the nearest 1/8 in (3 mm) and note the angle between walls.
- Check how far adjacent valances or cassettes project; provide corner dimensions so we can supply the correct connector or spacer.
- Confirm inside corners offer at least 2 1/2 in (6.4 cm) of depth; outside mounts may need returns or corner blocks for a flush look.
Depth & clearance: Leave 1 in (2.5 cm) between neighboring headrails to prevent collision when the shades move. If the bay angles vary, reach out for a template before placing your order.
Sliding Doors, Vertical Blinds & Drapery Tracks
Wide expanses and floor-to-ceiling openings benefit from extra stackback, dedicated vertical-blind allowances, and a precise hem clearance.
- For vertical blinds, add roughly 3 in (7.6 cm) on each side for overlap and deduct 1/2 in (1.3 cm) from floor-to-headrail height so vanes glide freely.
- Extend drapery tracks or rods 6–8 in (15–20 cm) beyond each side of the door so panels clear the glass when open.
- Measure finished drapery height from the mounting point to the floor and subtract 1/2 in (1.3 cm) for glide clearance.
- Note projection of handles or trim; specify ceiling vs. wall mount so we supply proper brackets.
Depth & clearance: Motorized tracks and fascia covers require roughly 4 in (10 cm) of depth; flag tighter openings so we can recommend low-profile hardware or a split stack configuration.
Skylight Shades
Measure base, height, and diagonal – the triangular opening must remain square so side channels align.
- Use a steel tape; laser tools can introduce errors along sloped openings.
- Label measurements base-height-hypotenuse so the factory references the correct sides.
- Check the roof pitch for clearance if the cassette projects into the room.
Depth & clearance: Inside mount requires at least 1 3/4 in (4.5 cm) of mounting depth for the tracks.
Trapezoid & Specialty Windows
Irregular shapes demand extra measurements. Always work from the narrowest width and shortest height.
- Map every edge: base, height, and any sloped sides. Record each to the nearest 1/8 in (3 mm).
- Verify bottom corners are true 90°; if not, note the angle for production.
- Order at the exact smallest width and height — the factory applies the precise deductions needed.
Depth & clearance: Square valances need roughly 2 3/4 in (7 cm) inside depth. For outside mounts, list any protrusions so spacer blocks can be included.
Avoid These Common Mistakes
- Rounding measurements to the nearest half-inch — stay precise to the nearest 1/8 in (3 mm).
- Assuming mirrored windows share the same size. Measure each opening independently.
- Forgetting to note power locations for hardwired or plug-in motors.
- Skipping depth checks on windows with cranks or security sensors.
- Mounting outside shades without confirming at least 3–4 in (7.6–10 cm) of flat space above the window.
- Reversing width and height on the order form — always list dimensions W × H.
Measuring FAQ
Can I mix inside and outside mounts in the same room?
Yes. Match the mount type to each opening. Inside mounts keep trim visible, while outside mounts deliver stronger blackout coverage or solve shallow frames.
How exact do my numbers need to be?
Record to the nearest 1/8 in (3 mm). The factory applies final deductions and will flag dimensions that fall outside product tolerances.
What if my window is out of square?
Capture the smallest width and shortest height. Add a note in your order about the variance; we can recommend outside mounts or slim spacer blocks when needed.
Centimeters ↔ Inches Converter
Enter a value in either field and we’ll do the math for you. Results round to two decimals so you can copy them straight into your worksheet.
Quick reference conversions:
- 1 in = 2.54 cm
- 12 in (1 ft) = 30.48 cm
- 30 cm = 11.81 in
- 96 in (8 ft) = 243.84 cm
Ready to Finalize Your Order?
Send us your worksheet and photos for a double-check, or schedule a professional measure if you’d like our team to verify on site.