Most measuring guides assume one thing: a clean rectangle. Real houses laugh at that assumption. Bay windows bump out in three sections, front entries carry arches, French doors are all narrow panes, and sliders are basically glass walls. Here's the honest version of what factory-built standard-size shutters can and can't do with each one — because a guide that tells you "everything fits!" is a guide trying to take your money.
Bay windows: three windows wearing a trench coat
A bay window is really three or more flat windows joined at angles — a wide center panel flanked by angled side panels. The trick is to stop seeing "a bay" and start seeing three separate windows. Measure each flat section on its own: width and height of each opening, three readings each way, same as a normal inside mount.
Match each section to a stocked RS size and order one shutter per section. The corner posts and frame mullions between sections cover the joints, so the finished job reads as one continuous treatment across the bay. Bay sections often vary by a fraction of an inch — measure every section individually, never measure one and copy it to the others.
- Treat each flat bay section as its own window — separate measurements, separate RS size
- Measure each section at three points; bays vary more than single windows
- Check the angle joints: frame mullions cover gaps up to about an inch at the corners
- Very shallow or very deep bays change the depth math — confirm your 1-3/4" minimum depth in each section
Arches, circles, and other curves: the honest no
Factory-built shutters are rectangles. Curves are not rectangles. If your window is a true arch, circle, or trapezoid, our shutters are not the right product for it — and we'd rather say that here than on a return form.
There is one common compromise worth knowing: many arched windows are really a rectangle with a half-circle cap. Shutter the rectangular lower section and leave the arch open — or fit the arch with a fixed specialty shape from a custom shop. You get the light control where it matters (eye level) without paying custom prices for the whole window.
French doors: measure each pane, mind the swing
French doors are all glass divided into small panes — and each pane is its own little window. Measure each pane separately. Be honest with yourself here: most French-door panes are too narrow or too short to fall inside any stocked RS range, and when that's the case our shutters can't fit that door. The size chart gives the final word.
When a pane does match, you mount on the door surface — and you have to clear two things: the door handle and the swing path. Doors that swing into the room need the shutter frame to clear the full swing arc, and handle projections eat into your depth. Measure the handle's projection and the swing radius before you order, not after.
Sliding glass doors: a different product entirely
Big sliders get covered by bifold or bypass-track shutters — panels that slide sideways on a track, exactly like the door does. Those are custom-manufactured to your opening's exact width, which puts them in the $20–$45-per-square-foot installed world. Our factory-built single panels are not slider products, and we won't pretend otherwise.
The practical move: put Prime View shutters on every standard window in the room and cover the slider with a separate treatment. You still delete the custom-shop bill on 80–90% of the room's glass.
Skylights: gravity wins
Skylights slope, sit out of reach, and fight gravity — louvered shutters assume a vertical panel with hand-reach tilt control. Motorized shades are the right product for skylights. We don't sell motorized shades, so here's your free advice anyway: don't buy shutters for a skylight from anyone.
The rectangle test
When in doubt, run this two-second test: can I draw a rectangle on the part I want covered and measure its width and height? If yes, measure it, run it through the size chart, and let the RS ranges decide. If the area you want covered isn't rectangular — true arches, circles, angled tops — our shutters aren't the right product, and our order sheet will tell you so rather than faking a fit.
Still unsure? The measuring guide walks through inside-mount and outside-mount measuring step by step, and every order gets a free review before anything ships — a second pair of expert eyes on your sizes.
Frequently asked questions
Usually yes — a bay window is really three (or more) flat windows joined at angles. Treat each flat section as its own window: measure each opening's width and height, match each one to a stocked RS size, and order a shutter per section. Corner posts and mullions cover the joints, so the finished look reads as one continuous bay treatment. Measure each section at three points (top, middle, bottom for width) — bay sections often vary slightly.