Measure the window opening at three points for width and three for height, use the smallest width and the largest height, then confirm your window’s depth clears the bracket before ordering.
Bamboo shades are cut to the eighth of an inch, so a single slipped measurement becomes a shade that binds, gaps, or refuses to sit flush. The measuring itself takes about five minutes per window, and the whole method comes down to two decisions: inside mount or outside mount, and which of your three readings you actually write down.
The sections below cover the inside-mount method, the outside-mount method, the depth limits that quietly disqualify some windows, and the mistakes that cause most returns. Grab a steel tape measure before you start — cloth tapes stretch and flex, and they are the single most common reason measurements land wrong.
How Do You Measure for an Inside Mount?
For an inside mount, measure the width of the window opening at three points and record the smallest number, then measure the height at three points and record the largest. The shade sits inside the frame, so it has to clear the tightest spot and still reach the sill.
Width first. Run your tape across the top of the opening, then the middle, then the bottom. Old windows are rarely square — a quarter inch of difference between the top and bottom is normal, and ordering the middle number is how shades end up scraping one side. Write down the smallest of the three and round down to the nearest 1/8 inch.
Height next. Drop the tape on the left side, in the center, and on the right, running from the top of the opening down to the sill. Use the largest reading and round up to the nearest 1/8 inch. A shade that’s a hair long can be adjusted; one that’s short leaves a permanent light gap at the sill.
Use a steel tape and record every measurement to the nearest 1/8 inch. The Shade Store’s woven wood guide follows exactly this pattern — smallest inside width, largest inside height.
How Do You Measure for an Outside Mount?
For an outside mount, measure the area you want the shade to cover, then add overlap: at least 2 inches of extra width on each side and 2 inches of extra height at both the top and bottom. The shade hangs on the wall or trim in front of the window, so it has to be larger than the opening to block light and look intentional.
Decide what the shade should cover before you measure anything. If you want the shade to span the trim, measure the full trim width; if you want it to reach past the trim for better light control, measure the wall area you’re willing to cover. Then add the overlap on top of that number — the 2-inch allowance per side is what stops daylight from leaking around the edges.
For height, start at the point where you want the shade’s headrail to sit. Mounting above the trim gives you more clearance and usually looks better, so add 2 inches above the opening for the headrail, then measure down to where you want the bottom edge to land. Total, that’s roughly 4 inches added to the opening’s height.
What Depth Does a Bamboo Shade Need?
An inside mount only works if your window has enough depth for the brackets, and the requirement changes with the lift system. Insufficient depth means the shade won’t sit flush or won’t fit at all — switch to an outside mount rather than forcing it.
Measure depth from the front edge of the window frame back to the glass, at the top of the opening where the brackets will sit. If your number falls short, don’t round up and hope. Check the product page’s Specifications tab for the exact minimum, and if your window still doesn’t clear it, order an outside mount instead.
| Measurement | Inside Mount | Outside Mount |
|---|---|---|
| Width | Smallest of three readings, rounded down to 1/8 inch | Area to cover plus 2 inches per side |
| Height | Largest of three readings, rounded up to 1/8 inch | Area to cover plus 2 inches top and bottom |
| Where to measure width | Top, middle, bottom of opening | Across the trim or wall span you want covered |
| Where to measure height | Left, center, right, down to sill | Headrail position down to desired bottom edge |
| Depth needed | 1/2 inch cordless; 1 1/2 inches cord loop or motorized | Set by the product’s Specifications tab |
| Flush mount depth | 2 1/4 inches cordless; 3 1/4 inches cord loop or motorized | Not applicable |
| Rounding direction | Width down, height up | Round overlap to the retailer’s increment |
Which Mistakes Cause the Most Returns?
Most wrong shades trace back to four habits: measuring once, using the wrong tape, mixing up the two mount types, and skipping the retailer’s rounding rule. Each one is avoidable in under a minute.
- Measuring in one spot. A single reading tells you nothing about an out-of-square opening. Three readings per dimension catches the lean before it becomes a return.
- Using a cloth tape. Fabric tapes sag and stretch. A steel tape is what the official guides specify, and it costs a few dollars.
- Blending the two methods. Inside mounts use the opening’s dimensions; outside mounts add overlap. Applying the wrong rule shifts your width by 4 inches.
- Ignoring the rounding increment. Round width down, height up, both to the nearest 1/8 inch — unless the retailer’s page says otherwise.
Once your numbers are written down, compare them against the depth requirements one more time before checkout. If you want to see which styles hold up best in real rooms, browse our tested bamboo window shade picks before you commit to a size.
The U.S. guidance behind all of this — three-point measuring, the smallest-width rule, and the 1/8-inch increments — is laid out in The Shade Store’s woven wood measuring guide.
FAQs
Should I round my measurements up or down?
For an inside mount, round the width down and the height up, both to the nearest 1/8 inch. Rounding width down keeps the shade from binding against a tight frame; rounding height up keeps it reaching the sill. For outside mounts, round to whatever increment the retailer requests, since overlap makes small differences less critical.
What if my window isn’t deep enough for an inside mount?
Switch to an outside mount. If your window frame can’t provide that, an outside mount sidesteps the depth requirement entirely and still blocks light.
Can I measure with a regular tape measure?
Use a steel or metal tape, not a cloth one. Fabric tapes stretch and sag, which throws off readings at the 1/8-inch precision bamboo shades are cut to. A basic steel tape from any hardware store is accurate enough, and it should be long enough to span your window in one pass without bending.
References & Sources
- The Shade Store. “Measuring Guide for Bamboo, Grasses and Woven Wood Shades” Source of the three-point measuring method, smallest-width rule, and 1/8-inch rounding.
- Home Depot. “Bamboo Woven Shade Sizing Guidance” Supports bracket depth requirements and the 2-inch minimum window depth.
- Blinds Chalet. “Bamboo Roller Shade Dimensions” Supports mounting depth and overlap guidance for bamboo shade orders.
