Bay Window Curtain Calculator
Bay windows are the hardest to dress. Enter each section's width to get the rod length around the bay (or straight across), how many panels to buy and where they go, and the curtain length.
How to measure a bay window
- Decide the rod height first, usually 4 inches above the highest window frame, and measure every section at that height: bay walls are rarely perfectly square.
- Measure each section along the wall from corner to corner: the left side, the center and the right side (or each section of a bow window).
- Measure the ends: how far the rod can extend onto the room walls beside the bay, often only 4–6 inches.
- Measure the drop from the rod height to the sill (for sill-length curtains or a window seat) or to the floor.
Bay rods come with adjustable corner connectors; check the kit covers your corner angle (shown by the calculator). Each corner needs its own bracket, and any section longer than about 60 inches needs a support in the middle.
Panel layouts for bay windows
| Layout | 3-section bay | Looks and works |
|---|---|---|
| Ends only | 2 panels | Frames the whole bay; doesn't close; cheapest |
| Ends and corners | 4 panels | Frames each window; can close if the panels are wide enough |
| Pair per section | 6 panels | Every window closes fully; most fabric |
| Straight across | 2 or more | Closes off the whole bay like an alcove |
For a regular window, use the curtain size calculator; for doors, the door curtain calculator. Sewing your own? The curtain fabric calculator works out the yardage.
Frequently asked questions
How do you measure a bay window for curtains?
Measure each window section separately, at the height where the rod will go: the two angled side sections and the center section, from corner to corner along the wall. Add them up for the rod length that follows the bay, plus a few inches at each end where the bay meets the room walls. Measure the height and the drop to the floor as for any window.
How many curtain panels do I need for a bay window?
For a three-section bay, the usual minimum is four panels: one at each end and one at each corner. For curtains that close completely over every window, use a pair on each section (six panels), each sized for its own section at about 2× fullness.
Should a bay window curtain rod go around the bay or straight across?
Around the bay (with a bay rod and corner connectors) frames each window and lets the curtains close against the glass. Straight across the opening is simpler and turns the bay into an alcove when the curtains are closed, but needs a longer single rod, often with ceiling brackets.
What is a box bay window?
A bay whose side windows meet the main wall at 90°, so it looks like a box sticking out of the wall. Most bays are angled instead, with the sides at 45° (the most common) or 30° to the wall. Bow windows are curved, made of four or more narrower sections.