How high should a chair rail be?

About a third of the wall height, which puts it near 32" in a standard eight foot room. The one height to avoid is exactly half — a rail at the midpoint cuts the wall into two equal bands and makes the room feel shorter than it is. A high wainscot at two thirds is a deliberate and very different look, and it works for the same reason.

How many panel boxes should a wall have?

Enough that the boxes are wider than they are tall, but not more than about twice as wide. Boxes taller than they are wide read as a row of doors; boxes much wider than that read as a layout that ran out of ideas. On a twelve foot wall with a 32" rail, four or five boxes usually lands in the right band — the calculator suggests a count from the proportions and lets you override it.

What size should the border between panels be?

Two to four inches is the usual range, and the same figure works for the gaps between boxes and the margins at the ends. Traditionally the bottom border is made slightly larger than the top, which corrects for the eye reading the centre of a frame as lower than it is. The border is the single biggest lever on how the wall feels: wider borders read as calmer and more formal.

How much molding do I need?

Four sides of every box, plus the chair rail and baseboard for the full run of the wall, plus fifteen to twenty percent. Miters eat more stock than people expect — every box is eight cuts, and a miter that closes on one side and not the other costs you the whole piece. Buy the waste; walking back to the store mid-installation costs more.

What about doors, windows and outlets?

Lay the boxes out on the clear runs between them and treat each run as its own wall. An outlet inside a panel box is the common trap: check the wall for boxes before you commit to a layout, and shift the spacing so outlets land in a border rather than through a mitered frame. It is far easier to move a layout than to move an outlet.

Wainscoting layout

Even picture-frame boxes across a wall, drawn as an elevation with the marks and cut lengths underneath. The panel field stops at the bottom of the chair rail, which is the measurement people get wrong. A true-size gap gauge below spaces the boxes off each other.

Wall length

Wall height

Chair rail height

Floor to the top of the rail

Boxes

Suggested from the wall proportions

Border

Sides, top and between

Advanced settings3" rail face · 5 1/2" base · 3" bottom · 15% waste

Chair rail face

How tall the rail itself is

Baseboard height

= 5.5"

Bottom border

Traditionally the larger one

Molding waste

Miters eat more stock than you expect

4 boxes across 144"

Box width

32 1/4"

Outside of the frame

Box height

21 1/2"

Molding needed

41.2 ft

Mitered pieces

Panel field

27 1/2"

Cut list for one box

2 × top and bottom45° miter both ends, long point to long point: 32 1/4"
2 × sides45° miter both ends, long point to long point: 21 1/2"
Chair railThe full run of the wall: 12.0 ft
Baseboard: 12.0 ft

Box dimensions are the outside of the frame, so those are long-point measurements — the longest edge of each mitered piece. Cut one box, hold it on the wall, and check it against the marks before you cut the other 3.

Marks from the corner

Box 1: 3" → 35 1/4"
Box 2: 38 1/4" → 70 1/2"
Box 3: 73 1/2" → 105 3/4"
Box 4: 108 3/4" → 141"

Gap gauge, at true size

Not the whole wall — the marks above already give every box position from the corner. What's worth printing is the margin between boxes, as a spacer you hold against the last box to set the next one. Print at 100%, check the ruler, then cut a scrap to this length.

Check this first

Put a tape on the printed ruler. If it does not read exactly 6 inches, the print was scaled — set the print dialog to 100% or “Actual size” and print it again. Do not cut wood from a template that failed this.

Margin between boxes

Cut a scrap to this length and use it to space each box off the last one — faster than measuring every mark, and every margin stays identical.

Worth knowing

Measure the wall in three places before you commit. Walls are rarely the same length at the ceiling as at the floor, and the layout should be built off the shortest reading so the last box does not run out of wall.

Where to buy this

41 ft of picture-frame moldingHome Depot Lowe's
12 ft of chair railHome Depot Lowe's
12 ft of baseboardHome Depot Lowe's

Lineal feet with your waste allowance already in them. Profiles vary between mills, so buy the wall in one go.

Plain search links, nothing sponsored. Prices and stock are the shop's, and a local lumberyard will usually beat both on solid stock.

Worked example: a 144" wall

A 144" wall with the chair rail at 36" over a 5 1/2" baseboard takes 4 picture-frame boxes, each 32 1/4" wide and 21 1/2" tall outside the frame.

Each box is two 32 1/4" pieces and two 21 1/2" pieces, mitered at 45° and measured long point to long point: 16 pieces in all.

With 15% waste that is 41.2 ft of molding, plus 12.0 ft of chair rail and 12.0 ft of baseboard.

Boxes: 4
Box width: 32 1/4"
Box height: 21 1/2"
Molding needed: 41.2 ft
Mitered pieces: 16

These are the figures the calculator above opens on. Change any field and it works the same problem for your numbers.

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About wainscoting

How high should a chair rail be?: About a third of the wall height, which puts it near 32" in a standard eight foot room. The one height to avoid is exactly half — a rail at the midpoint cuts the wall into two equal bands and makes the room feel shorter than it is. A high wainscot at two thirds is a deliberate and very different look, and it works for the same reason.
How many panel boxes should a wall have?: Enough that the boxes are wider than they are tall, but not more than about twice as wide. Boxes taller than they are wide read as a row of doors; boxes much wider than that read as a layout that ran out of ideas. On a twelve foot wall with a 32" rail, four or five boxes usually lands in the right band — the calculator suggests a count from the proportions and lets you override it.
What size should the border between panels be?: Two to four inches is the usual range, and the same figure works for the gaps between boxes and the margins at the ends. Traditionally the bottom border is made slightly larger than the top, which corrects for the eye reading the centre of a frame as lower than it is. The border is the single biggest lever on how the wall feels: wider borders read as calmer and more formal.
How much molding do I need?: Four sides of every box, plus the chair rail and baseboard for the full run of the wall, plus fifteen to twenty percent. Miters eat more stock than people expect — every box is eight cuts, and a miter that closes on one side and not the other costs you the whole piece. Buy the waste; walking back to the store mid-installation costs more.
What about doors, windows and outlets?: Lay the boxes out on the clear runs between them and treat each run as its own wall. An outlet inside a panel box is the common trap: check the wall for boxes before you commit to a layout, and shift the spacing so outlets land in a border rather than through a mitered frame. It is far easier to move a layout than to move an outlet.