Picture Frame Molding Calculator

Picture frame moulding: cut lists without pretending sawdust does not exist

A mitered rectangle is elegant because the geometry is simple—until you meet real wood, real blades, and real rabbets that do not match the catalog drawing. This guide explains the cut-length rule the calculator uses, where framers deviate from textbook math, and how to keep waste percentages honest.

The long-side rule for 45° corners

For a rectangular frame with inside opening W × H measured at the sight line (the reference you want the art to reveal), and a moulding whose relevant width is w, the outside length of each rail—what many chop saws label as the long point of a 45° miter—is W + 2w for horizontal members and H + 2w for vertical members. Summing four sticks gives 2(W + H) + 8w of raw stick length before waste.

That w is the number you must trust. It is not always the same as the decorative face you show the client; sometimes the limiting dimension is set by the rabbet depth or joiner block. If your shop measures differently, change the field until dry-fits close.

Waste is not laziness; it is insurance

Grain tear-out, a bad first miter, and “I measured twice but the universe laughed” are all priced into professional quotes. The waste slider is where hobbyists should admit they are human. If you are batching many identical frames, waste falls; if you are learning, it rises.

Stock length and the fiction of perfect nesting

Dividing total inches by an eight-foot chop assumes you can nest cuts without loss. You cannot, always. Treat stick counts as a phone-call to the lumber yard, not a guarantee you will clear the rack in one piece.