How to measure window size?

All LazBlinds shades are no-drill, inside mount — they fit inside your window frame with no holes and no tools. That makes measuring simple, but it also means one number matters more than the rest: your frame depth. Check it first, then measure width and height.

Tools you'll need: a steel tape measure (cloth ones stretch — don't use them) · pencil · notepad · a step stool for high windows · a helper for windows wider than 48 inches.

Check your frame depth first

Step 1 — Check the frame depth (most important)

Measure from the glassto the front edgeof the frame. That's your usable depth.

How much depth do you need? It depends on the shade:

Roller & Zebra shades: at least 2 1/2 inches— the roller tube at the top needs the room.
All other shades (honeycomb / cellular, venetian / aluminum): at least 1 1/2 inches.

The surface must also be flat and solid. Rounded, warped, or flexible vinyl frames don't hold no-drill brackets well. If your frame is too shallow or not flat, email us a photo before ordering — we'll tell you honestly whether it will work.

Measure the width

Step 2 — Measure the width

Measure the inside width of the frame at three points: top,middle, andbottom.

Write down all three, then use the smallest one. That's the width you enter at checkout.

Enter the exact number — don't subtract anything yourself. We make the small deduction needed for the shade to operate smoothly.

Measure the height

Step 3 — Measure the height

Measure the inside height at three points: left,center, and right.

Use the largest of the three — that guarantees full coverage top to bottom.

Again, enter the exact number. No need to round up or subtract.

Check for obstructions

Step 4 — Check for anything in the way

Look for anything that sticks into the window opening:

Window crank handles or locks
Security sensors or alarm contacts
Tilt-in sash hardware
Deep window sills or decorative trim

Note them down. Some are easy to work around (measure around them); others mean an inside mount won't sit flush — if you're unsure, send us a photo.

Measure every window

Why every window needs its own measurement

Windows in the same room are rarely identical — even a quarter-inch difference matters for an inside mount. Measure each window separately, and label your notes (e.g. "Living room — left window").

Measure twice. Two people measuring independently is even better.

Common mistakes

Common measuring mistakes

Using a cloth or fabric tape measure — it stretches, and you'll be off by up to half an inch.
Skipping the frame depth check — the #1 reason a no-drill shade won't stay up.
Measuring only once, or only in the middle.
Subtracting or rounding "to be safe" — just give us the exact number.
Assuming all windows in a room are the same size.
Measuring to the outside of the trim instead of the inside of the frame.
Ordering before checking for crank handles, locks, or sensors.

Not sure you measured right?

Email your three numbers (width, height, depth) and a photo of the window to service@lazblinds.com before you order. Custom shades are made to the dimensions you submit, so we'll double-check them with you for free — it's a lot easier to fix a measurement than a finished shade.