Reference formulas and worked examples below keep their stated units. Monetary examples use USD; dimensional examples use US customary units unless labeled otherwise. Metric calculator inputs are converted to these reference units before calculation. Choosing another currency does not convert example amounts or exchange money.
How to use this wainscoting calculator
This model uses one continuous top rail, one bottom rail, and a stile at each panel boundary, including both ends.
How the calculation works
Inside layout width = wall width − two side margins. There are panel count + 1 vertical stiles.
Each clear opening = (inside width − total stile face widths) ÷ panel count. Clear height = overall height − top rail width − bottom rail width.
Basic trim length = two full-width rails + all stiles between the rails. This is linear material before cuts and waste.
Worked example
A 120 in wall with four openings, 3 in side margins and 2.5 in trim has 114 in inside width. Five stiles use 12.5 in, leaving four 25.375 in clear openings. At 36 in high, the clear opening height is 31 in.
Limits and assumptions
A simple rectangular, single-wall layout. Corners, doors, windows, outlets, wall irregularity, miters, saw kerf, and stock-length optimization are not included.
Frequently asked questions
Does panel count include the stiles?
No. Four panels means four clear openings and five vertical stiles in this model.
What does trim length include?
Two continuous horizontal rails and all vertical stiles between them. It excludes trim waste, caps, and returns.
Can I use different widths for rails and stiles?
This first version uses one face width for both. If your design differs, calculate the layout from your actual materials before cutting.