How to Measure Your Windows

Five minutes with a steel tape measure is all it takes. Measure in inches, write everything down before you start configuring, and remember: measure every window, even ones that look identical — they rarely are.

First, choose: inside or outside mount

Inside mount sits inside the window recess for a clean, built-in look. You need about 3" of flat depth for the hardware. Outside mount hangs on the wall above the window, covering the whole opening — the better choice for shallow recesses, cranks and handles that stick out, or maximum light blocking.

Inside mount: measure the opening

• Width: measure the recess at the top, middle, and bottom. Use the narrowest of the three.
• Height: measure left, center, and right. Use the tallest.
• Give us the exact opening size — don't subtract anything. The factory makes the small clearance deductions so the blind fits and rolls freely.

Outside mount: measure the coverage

• Width: the opening plus at least 1.5" on each side to block light gaps.
• Height: from where the top of the blind will mount (usually 2–3" above the opening) down to the sill — or lower if you want it to drop past.

The three classic mistakes

• Using a cloth tape or a phone app instead of a steel tape measure.
• Measuring the old blind instead of the window — old blinds already have deductions built in.
• Assuming two windows match. Measure both. It's 60 seconds that saves a remake.