Wainscoting is traditionally one third of the wall height, cap included: 32 inches on an 8 foot wall and 36 inches on a 9 foot wall. On a 12 foot wall at 32 inches, picture frame molding works out to 5 boxes of 24 by 15¼ inches with 4 inch gaps around them, which takes 32.7 feet of frame molding, five 8 foot lengths with waste.
How the wainscoting height is set
Bob Vila's rule of thumb is that "wainscoting height should be a third of the wall's height, including the cap or any moldings", scaling to "about 32 inches for rooms with 8-foot walls". The calculator offers the other heights from the same guide too:
| Where | Height to the top of the cap |
|---|---|
| 8 ft walls, one third | 32 in |
| 9 ft walls, one third | 36 in |
| Tall wainscot | two thirds of the wall |
| Bathroom | 40 in, or 8 in above the tub |
| Kitchen beadboard | up to the upper cabinets, 54 in |
How the panels are spaced
Every wall between two corners, or between a corner and a door, gets its own layout, so the panels always fit exactly. The calculator picks the number of panels whose width is closest to the width you want, then solves for the exact width.
Picture frame box width = (wall width − (boxes + 1) × gap) ÷ boxes
Raised or flat panel width = (wall width − (panels + 1) × stile width) ÷ panels
The panel field, the height the boxes or panels live in, is the wainscot height less the ¾ inch cap, the chair or top rail and the baseboard.
Worked example: picture frame on a 12 ft wall
| Step | Numbers | Result |
|---|---|---|
| Height | 8 ft ÷ 3 | 32 in |
| Panel field | 32 − ¾ cap − 2½ chair rail (1x3) − 5½ baseboard (1x6) | 23¼ in |
| Boxes | (144 − 4) ÷ (24 + 4) = 5 | 5 boxes |
| Box width | (144 − 6 × 4) ÷ 5 | 24 in |
| Box height | 23¼ − 2 × 4 | 15¼ in |
| Frame molding | 5 × 2 × (24 + 15¼) in | 32.7 ft |
With 10% for miters, that is five 8 foot lengths of frame molding, plus 12 feet each of chair rail, baseboard and cap. Add walls with "Add a wall" and each one gets its own box width.
Raised panel and flat panel wainscoting
Frame-and-panel wainscoting is built from a bottom rail, a top rail, vertical stiles and panels set between them (raised or flat). With 1x4 stiles (3½ inches) on the same 12 foot wall and a 36 inch height, the calculator fits 5 panels 24 5/8 inches wide between 6 stiles, each panel 26¼ inches tall (36 − ¾ − 3½ − 5½). The stiles come out of the boards list with the rails; the panels are listed by size so you can cut them from sheet goods.
Beadboard wainscoting
Beadboard comes in 4 by 8 foot sheets. Stood on end, one sheet covers 4 feet of wall; for a low wainscot one sheet can be cut into several strips. At 32 inches the field is 23¼ inches, so each sheet yields four strips, 16 feet of wall. A 12 foot and a 10 foot wall (22 feet, plus 10%) need 2 sheets. Beadboard gets the same chair rail, baseboard and cap as the other styles.
Board sizes used
| Board | Actual width | Typical use |
|---|---|---|
| 1x3 | 2½ in | chair rail |
| 1x4 | 3½ in | top rail, stiles |
| 1x6 | 5½ in | baseboard, bottom rail |
| 1x8 | 7¼ in | tall baseboard |
Widths are ProWood's actual dimensions for nominal boards. Change any of them in the calculator and the panel field and panel sizes follow.
Tips before you cut
- Measure every wall at the wainscot height; old walls are often out of square, and a gap that is even at the floor may not be at the cap.
- Keep outlets and switches in mind: a box edge that lands on an outlet looks wrong. Nudge the box width up or down and see how the layout changes.
- Mark a level line for the top of the chair rail first, then set the boxes from it.
Next steps
- Prefer vertical battens? The board and batten calculator spaces them evenly on the same wall.
- Horizontal planks: the shiplap calculator.
- Replacing the baseboard too: the baseboard calculator totals the lengths.
- Cutting the frame corners: the miter angle calculator.
- Paint the wall above: the paint calculator.
More wall coverings are listed in drywall, paint and walls.