Box Pleating Grid Calculator

The two heuristics catch different failure modes: minGridFromFlaps (2 × average flap length + body width) protects against a few very long flaps that need room to reach the center, while minGridFromArea (from total flap length scaled and square-rooted) protects against many short flaps that pack in tightly. Averaging them could understate the grid for a model that's extreme in either direction, so the calculator takes the max to guarantee the grid is large enough for whichever constraint actually dominates your design.

This calculator gives a rough N×N sizing estimate from just four numbers — flap count, average flap length, body width, and paper size — treating flaps as generic linear features. A real TreeMaker layout accounts for the exact tree structure, flap angles, and how efficiently flaps can be packed around each other, which can shrink or grow the needed grid considerably from this estimate. Use this number to pick a starting paper size before you sit down to design, not as a substitute for actually laying out the crease pattern.

Difficulty score is (recommendedGrid / 8) + (numFlaps / 6), capped at 10 — so it rises both with finer grid resolution (more, smaller cells to crease precisely) and with more flaps to manage simultaneously. A high score doesn't mean the design is impossible, but it signals that precise crease placement and careful pre-creasing will matter more than usual; it's worth practicing a simpler box-pleated model first if you haven't folded from a grid before.

The calculator has no information about how flaps are arranged relative to each other, so estimatedDiagonals (numFlaps × avgFlapLength × 1.5) is a rough proportional guess rather than a count derived from a real crease pattern. Diagonals in box pleating come from 45° folds that redirect paper between grid cells, and their true number depends entirely on the specific tree structure — this output exists to give you a ballpark sense of crease density, not an exact figure to fold from.