Guide
How to measure for window shades
Wrong size is the only expensive mistake in this category. Measure twice, then shop the width you actually have — not the width you wish the house came with.
What’s your window size?
Inside mount
The shade sits in the casing. It looks built-in and shows off decent trim. You need enough depth for brackets — often around 1.75\". Measure width at top, middle, and bottom; shop the narrowest.
Outside mount
The shade sits on the wall or trim. Better for shallow windows, out-of-square openings, and blackout. Size the shade larger than the glass so light doesn’t stripe the edges.
Window depth
If the casing is too shallow for an inside-mount headrail, don’t force it. Outside mount is the grown-up answer, not a compromise.
Exact vs nominal sizes
A 36\" shade is the ordered width. Manufacturers often deduct a small amount for inside-mount clearance. If you are replacing a shade, copy the size on the headrail tag when you can.
Common mistakes
- Measuring only once, in the middle, on a window that’s not square.
- Buying outside-mount width for an inside-mount install.
- Ignoring depth, then returning a perfectly good shade.
- Assuming a “36-inch window” is 36.000 inches. It almost never is.
Don’t see your size?
Tell us what you need and we’ll notify you when one arrives. This also tells us which lots are worth buying.
Questions
- Should I measure the glass or the frame?
- For inside mount, measure the inside of the casing — the opening the shade has to fit into. For outside mount, measure the area you want covered, usually including trim.
- My window is 35.5 inches. What do I buy?
- Inside mount: shop 35" if that’s the nearest stock size that still clears the frame. Outside mount: a 36" shade will cover it. Use the finder above.