How to Measure Windows for Custom Window Treatments
A plain-English guide to inside vs. outside mount, what each product type needs, and the mistakes that trip people up — plus, every Angel Drapery order includes a free in-home measurement, so you never have to get it exactly right on your own.
Try the interactive Measurement Wizard →Inside mount or outside mount?
Inside Mount
The treatment sits inside the window frame, flush against the wall — a clean, built-in look. Measure the exact inner frame opening: width at top, middle, and bottom (use the smallest), height at left, center, and right (use the smallest), since most frames aren't perfectly square. Give us that exact opening measurement — don't deduct anything yourself, we make the factory deductions. Shades generally need about 2–3" of flat frame depth to sit flush.
Outside Mount
The treatment mounts on the wall or trim around the window, covering the frame entirely — better for shallow frames, uneven openings, or when you want a window to look larger. As a rule of thumb we add about +5" width / +6" height beyond the opening for roman and roller shades, and 2–3" per side for drapery, to block light gaps. Already know the exact finished size you want? Enter that directly.
What each treatment needs.
Custom Drapery
Width: window/opening width plus stacking room — generally +10" or more per side, scaling up for wider windows, so panels can clear the glass fully when open.
For ceiling-mounted rods/tracks: ceilings are often uneven, so measure ceiling height at left, center, and right. Finished height = ceiling height − rod/track thickness (motorized ceiling track ≈ 1.25", standard ceiling track ≈ 1") − floor clearance (0.5–1"). If the gap from window top to ceiling is over 30", the rod can instead be mounted at the midpoint. For a wall-mounted rod, finished height is simply ceiling height − 4.5" — no separate floor clearance needed.
2-fold pinch pleat gives a tailored, streamlined look; 3-fold pinch pleat is fuller and more traditional; ripplefold gives a modern continuous wave and pairs well with motorized tracks — though it does take up more stack space at the sides when open than pinch pleat styles. For ripplefold we only need your track length and drop, and calculate carriers and fullness (60/80/100/120%) for you.
Roman Shades
Available in 6 styles — flat, slouch, soft, front fold, reverse fold, and hobbled — with 3,000+ fabric options, optional lining, valance, cordless or motorized lift.
Inside mount needs about 2–3" of frame depth to sit flush; outside mount adds roughly +5" width / +6" height beyond the opening.
Cordless and motorized lift systems change the hardware clearance needed at the top of the shade — confirmed at your free in-home visit.
Roller, Zebra & Sheer Shades (Luma Collection)
Our Luma collection covers roller, zebra (alternating sheer/solid bands), sheer, and dual (double-layer) shades — maximum single-panel width is 118"; wider windows split into multiple panels.
Outside mount adds roughly +5" width / +6" height beyond the opening, same as roman shades, to block light gaps at the edges.
Choose from plastic chain, stainless chain, cordless, or motorized control — motorized and Matter-enabled options need power or charging access considered before install day.
Hunter Douglas, Shutters & Blinds
The full Hunter Douglas lineup (Duette, Silhouette, Palm Beach shutters, and more) is priced through a free consultation rather than the online configurator.
Frame depth matters most for shutters — panels and hinges need real clearance to swing freely, matched to your actual window muntins.
Bay windows, corner windows, arches, and other special shapes always go through an in-home consultation rather than a self-measured order.
Common measuring mistakes.
Using a cloth tape measure
Fabric tape stretches. Use a steel tape measure to the nearest 1/8" — that's the precision that keeps a measurement accurate from the living room to the workroom.
Measuring only once
Framing settles over decades — measure width and height in three spots and use the smallest number for inside mount so the finished piece always fits.
Deducting anything yourself for inside mount
Give us the exact inner frame opening as measured — don't subtract for clearance. We make the correct factory deductions on our end; deducting twice is a common cause of a too-small finished piece.
Forgetting obstructions
Door handles, blinds already installed, outlets, and radiators can all interfere with drapery stack-back or shade projection — worth noting before ordering.
Measuring FAQ
Do I need to measure my own windows?
No — every Angel Drapery order includes a free in-home measurement by our own team before anything goes into fabrication. This guide is meant to help you understand the process, compare mount options, and know roughly what to expect walking into your consultation.
What tools do I need if I want to measure myself first?
A steel tape measure (not cloth), a pencil and paper or phone notes app, and a step stool for taller windows. Measure width in three places (top, middle, bottom) and height in three places (left, center, right), and always note whether you're measuring for inside or outside mount.
What's the difference between inside and outside mount?
Inside mount sits within the window frame for a flush, built-in look and needs adequate frame depth. Outside mount covers the frame and wall around it, which works better for shallow frames, uneven openings, or when you want a window to appear larger. We help you choose during the free consultation.
What's the difference between ripplefold and pinch pleat, style-wise?
Ripplefold gives a modern, continuous S-wave look and pairs especially well with motorized tracks — it does take up a bit more stack space at the sides when fully open than pinch pleat does, worth knowing if wall space beside the window is tight. Pinch pleat (2-fold or 3-fold) gives a more traditional, tailored look, with 3-fold reading fuller and more formal. For ripplefold, we only need your track length and drop and calculate the rest (carrier counts, fullness percentage) for you.
What if my walls or window frames aren't perfectly square?
Very common in older homes across the San Gabriel Valley — craftsman bungalows and mid-century houses especially. This is exactly why we always use the smallest of three measurements per dimension, and why in-home measurement exists: our workroom builds to the tightest number so everything still fits and operates smoothly.
Is the in-home measurement really free?
Yes, with no obligation to purchase. We come to you, measure every window ourselves, and show fabrics and samples in your actual lighting before you commit to anything. If you're not in our San Gabriel Valley service area, or just want to get a feel for materials first, you can also order up to 10 free fabric swatches online (you only pay shipping).
What if I measure it myself and get it wrong?
If your own measurement turns out to be off, we can remake or adjust the piece — you'd just cover return shipping both ways. It's a straightforward fix, but ordering free swatches first and measuring carefully (or booking the free in-home measurement) is the easiest way to avoid the extra shipping cost and wait entirely.