How to measure for roller shades

Five minutes with a steel tape is all a custom shade needs. Here's exactly where to measure for each mount, what to write down, and what we take care of so you don't have to.

The one rule before anything else: measure every window, even the ones that look identical. Openings in the same room routinely differ by a quarter inch or more, and a custom shade is cut to your number — to the eighth of an inch, up to 118″ wide.

Step 1 — Pick your mount

Inside mount

The shade lives inside the window opening: trim stays visible, the look is built-in and clean. You need about 2″ of flat, unobstructed depth at the top of the opening for the brackets. Expect a sliver of light along each edge — that's the clearance any inside-mount shade needs to roll.

Outside mount

The shade mounts to the wall or trim and covers the whole opening. Choose it when the opening is shallow, out of square, has cranks or sensors in the way — or when you want a blackout fabric to actually black out the room, since overlapping the opening beats edge gaps.

Not sure?

Deep, squared openings with clear depth: inside mount looks best. Everything else: outside mount is the forgiving choice. Blackout bedrooms almost always want outside mount with generous overlap.

Step 2 — Width

Inside mount: measure the opening's width in three places — top, middle, bottom — and keep the narrowest number. Openings are rarely perfectly square, and the narrowest point is what the shade has to clear. Enter that number as-is: we make the hardware deductions for you, so the clutch, brackets, and fabric all clear the opening you measured. Don't subtract anything yourself — a pre-deducted measurement gets deducted twice and ends up narrow.

Outside mount: decide the coverage you want, not the opening size. Add roughly 1½–2″ beyond the opening on each side; more overlap means less light creep at the edges.

Step 3 — Height

Inside mount: three measurements again — left, middle, right — and keep the longest. A shade that's a touch long simply rests its hem bar at the sill; a shade that's short leaves a gap.

Outside mount: measure from where the top of the shade will sit — typically 2–3″ above the opening — down to the sill, apron, or floor, wherever you want the shade to stop.

Step 4 — Write it down to the eighth

Width first, then height, to the nearest ⅛″ — the configurator accepts eighth-inch entries directly (48, 48.125, 48.25, …). Steel tape, not cloth; and if two of your three measurements disagree, trust the tape, not memory.

Common mistakes we see

Pre-deducting

Subtracting "clearance" from an inside-mount width before ordering. Don't — deductions are our job, and doing it twice makes a narrow shade.

Measuring one window for many

Same-size-looking windows differ. Measure each opening and label the numbers ("kitchen left", "kitchen right").

Rounding to the half inch

An eighth of an inch is visible at the edge of an inside mount. Record the real number; we cut to it.

Measured up?

Enter your numbers and see your price instantly — Design your shade