Ordering blinds that don't fit is almost always a measuring problem, not a product problem. The good news: measuring takes about 10 minutes per window, and you only need one tool — a steel tape measure. (Don't use a cloth tape; it stretches and your measurements will be off.)
Step 1: Choose inside mount or outside mount
Inside mount means the blind sits inside the window frame. It looks clean and tailored, but your frame needs enough depth for the headrail — most blinds need at least 2 inches of depth, and cordless cellular shades a bit more.
Outside mount means the blind hangs on the wall or trim around the window. Choose this if your frame is shallow, if you want to block more light (great for blackout shades), or if you want to make a small window look bigger.
Decide this first, because you measure differently for each.
Step 2: Inside mount measurements
- Width: Measure the inside of the frame at the top, middle, and bottom. Write down all three and use the narrowest number. Your blind has to fit the tightest spot.
- Height: Measure the inside of the frame on the left, in the center, and on the right. Use the longest number.
- Depth: Measure from the front of the frame back to the glass. If you have less than 2 inches, switch to an outside mount.
Write it down as width x height — width always first. So "34 x 60" means 34 inches wide, 60 inches tall.
Important: order your exact measurements. Don't subtract anything yourself. The manufacturer takes a small deduction (usually 1/8" to 1/4") off the width so an inside-mount blind clears the frame. If you deduct too, your blind arrives too narrow and light leaks in around the edges.
Step 3: Outside mount measurements
- Width: Measure the window (or trim, if you want to cover it) and add overlap — typically 3 inches per side, so 6 inches total. More overlap means less light gap, which matters most for blackout and room-darkening shades.
- Height: Measure from where you want the top of the blind to sit (usually 2 to 3 inches above the trim) down to where you want it to end — the sill, or the floor for a full-length look.
Outside mount is more forgiving than inside mount, but still measure twice.
Step 4: Measure every window
Don't measure one window and order for the whole room. Windows in the same house are often a fraction of an inch different, and a fraction of an inch is the difference between a blind that fits and one that doesn't.
Buying a stock size?
If you're ordering a stock-size blind rather than a custom one, pick the closest size that fits your narrowest width measurement for an inside mount, or the next size up from your window width for an outside mount. Check the product's listed sizes against your measurements before ordering — for example, our stock faux wood and vinyl mini blinds come in set widths and heights, so match your window to the nearest size that fits.
The mistakes we see most
- Using a cloth tape measure. It stretches. Use steel.
- Measuring once. Measure width in three places and height in three places, every window.
- Deducting for clearance yourself. Order exact measurements; the manufacturer handles the deduction.
- Writing height first. It's always width x height. A 60 x 34 blind will not fit a 34 x 60 window.
- Assuming every window matches. They usually don't.
Still unsure?
Measure twice, write down width x height for each window, and reach out to us before ordering — a quick check beats a return. Browse our cellular shades, faux wood blinds, and aluminum mini blinds to find the right fit for your windows.