Accent Wall Planner

How it works

The math behind your plan

Every number the planner gives you comes from one small, transparent set of rules. Here they are, so you can check the plan against your own tape measure.

One idea: every style is a grid on a wall

Picture-frame molding, board & batten, wainscoting, and slat wall look different, but under the hood they are the same problem — a grid of rectangles laid out inside a wall. The only thing that changes between styles is whether a rectangle is the trim (a batten or a slat) or is the opening the trim frames (a picture-frame panel). Solving the grid once and reading it four ways is what keeps the results consistent across every style.

Step 1 — the usable area

Starting from your wall's width and height, the planner subtracts the margins on all four sides to get the inner area the grid has to fill. If the margins leave no room — say a 12-inch margin on a wall only 20 inches wide — it does not draw a broken grid; it tells you the margins are too big and to reduce them.

Step 2 — solving each axis

Each axis (across, then down) is solved on one firm rule: exactly one of the box size or the gap can be "even" — the one that flexes to absorb the leftover space. That gives two honest layouts and rules out an impossible third:

  • Even boxes, fixed gap — you pin the gap between boxes, and the boxes stretch to share the remaining width evenly. This is picture-frame molding and wainscoting.
  • Fixed boxes, even gap — you pin the stock width (lumber can't flex), and the gaps between pieces stretch to space them evenly. This is board & batten and slat wall.
  • Custom sizes — instead of "even," you give each box its own width or height as an explicit list. This is the mixed-size case a wide-center accent wall needs, and it's treated as the general rule, not an afterthought.

Trying to make both the size and the gap "even" is underdetermined — nothing pins the geometry down — so the planner says so and falls back to a zero gap rather than guessing.

Step 3 — the long-point miter math

This is the part worth getting right. Each box in a picture-frame grid is made of four pieces mitered at 45° at the corners. The measurement that matters for cutting is the long point — the longest edge of each mitered piece, corner tip to corner tip.

The planner computes it directly from the box's outer size: the top and bottom pieces are cut to the full width of the box, and the left and right pieces to the full height of the box. Because each piece spans the box's entire outer dimension, the four pieces overlap at the corners — which is exactly what a 45° miter joint looks like. In other words, the long-point cut length of a piece equals the box's outer dimension on that side, and the visible opening inside the frame is the box dimension minus twice your molding's face width (one width on each side).

If your molding is so wide that two widths leave no opening inside a box, the planner flags it rather than drawing a solid rectangle — a sign to use narrower stock or larger boxes.

Step 4 — the cut list

Every piece the grid produces is rolled up into a cut list. Two pieces with the same role, the same length, and the same miter are the same cut — whether one came from a row and the other from a column — so they're merged and counted, and the list is sorted longest first, the order you actually cut in to make the most of a board. Lengths are shown as tape-measure fractions rounded to the nearest 1/16 inch (so you read 22 3/4 in, not 22.75), while the total is given in decimal linear feet for estimating how much stock to buy.

Distribution presets

In custom mode you can seed the box sizes with one tap — Even, a wide Center panel, or emphasis on the Ends. Each preset lays out sizes that fill the wall, snapped to the nearest quarter inch (a mark you can actually find on a tape) and never smaller than an inch. From there you can hand-edit any box.

It warns; it never crashes

A plan you can't build is worse than a warning, so bad inputs never produce a blank screen or a nonsense drawing. Instead the planner keeps drawing the honest result and adds a plain-language note:

  • Boxes or battens that overflow the wall are reported by exactly how many inches.
  • A solved gap under an inch is flagged as cramped.
  • Molding too wide for its box, or margins that leave no room, are called out.

One honest limit: in the fixed-stock styles (board & batten, slat wall) and in fully custom layouts, a grid that is too small for the wall isn't auto-centered — the pieces simply abut or leave bare wall, shown at true proportions so what you see is what you'd build.

Assumptions to keep in mind

  • The wall is treated as a perfect rectangle; real walls rarely are, so measure yours.
  • The molding's face width is uniform, and long-point lengths assume clean 45° miters.
  • Everything is drawn at 1:1 with the wall — no fudge factor — so trust the drawing, but confirm each cut on your own stock before you make it.

Try it by style