How the calculator works

The wall it models

The model is one flat rectangular wall, with full-height or partial-height paneling. Dimensions are entered in inches or centimetres; calculations use inches internally and convert the displayed measurements. Positions refer to the wall’s left edge and the finished floor.

Vertical strip dimensions are their visible face width. Horizontal rail dimensions are their visible face height. Enter actual measurements rather than assuming a nominal lumber size is its finished size.

Equal spacing and suggested arrangements

For equal spacing with a strip at each wall edge, the clear gap is the wall width minus the combined strip widths, divided by the number of spaces between strips. Six strips create five spaces. The preferred gap helps compare options; it is not a promise that an exact gap will fit every wall.

Suggestions compare alternative strip counts and, where available, unequal spacing that retains the chosen count while avoiding marked fixtures. The search considers the measurements and settings entered. It does not try every possible arrangement or decide which will look best in your room.

Individual adjustments can change the gaps. Use the measurements for the selected arrangement rather than applying the equal-spacing formula to a manually adjusted plan.

Windows, outlets and switches

Fixtures are rectangular areas measured to the outside of the window casing or electrical cover plate. Extra clearance is a planning buffer around those dimensions, not a statement of a building-code requirement.

The vertical window setting either checks for strips that should stay clear or splits crossing strips into pieces above and below the casing. The horizontal setting independently checks for rail clashes or splits rails at the casing. Split piece ends follow the casing edges; they do not automatically include the extra clearance buffer.

Outlets and switches remain clash checks. The tool does not automatically notch trim around them or determine whether an electrical box, cover or extension is suitable. A clear front view does not resolve depth or electrical requirements.

What the cutting list includes

The list reports finished lengths of the modeled vertical strips and horizontal rail pieces. A single strip position can produce several pieces when a window or rail interrupts it. Totals follow the current layout and window settings.

The cutting list gives finished piece lengths. It does not work out which stock boards to buy or how to cut the pieces from them. They do not include saw kerf, defects, waste allowance, special end profiles or how pieces should be packed into available board lengths. Backing sheets, adhesive, fasteners, caulk and paint are outside the list.

What we have checked

Automated checks cover spacing geometry, window splits, rail positions and individual heights, obstacle clearance boundaries, cut totals, impossible layouts and saving/reopening project data.

Browser reviews have also used realistic example setups: a plain wall, partial-height paneling with an outlet, a full-height wall with a window, a window with an extra rail, and a busy wall with several fixtures. These checks help find software errors; they are not physical installation tests or professional certification.

Saving, printing and reporting a problem

Saved projects stay in the browser where you save them. Download a project file if you want a separate copy or to reopen it on another device. Printing creates a measurement sheet, not approval that a plan is ready to install.

If a result seems wrong, see Contact for what to include in a bug report. The Privacy page explains browser storage. For practical instructions, return to the calculator and its usage guide.