How to size a pattern to fit your panel opening

Every pattern on this site is built once, as geometry, and rebuilt to your exact panel width at download time, so sizing is mostly a matter of measuring your opening correctly and checking it against the pattern's declared range.

Measure the opening, not the glass

Measure the finished opening the panel needs to sit in, at its narrowest point if the frame is not perfectly square, and subtract a small clearance, typically 1/8 in to 3/16 in per side, so the finished panel is not fighting the frame.

Check the pattern's size range

Every pattern page on this site lists a minimum and maximum width. Choosing a size outside that range is refused before checkout, not silently allowed, because the cuttability checks are only verified within that declared range.

Why the checks are rerun per size

Interior angles do not change with panel size, since scaling a shape up or down does not change its angles. Piece width and glass area do change with size, in direct proportion. Rerunning the width and area checks at your exact chosen size, rather than only at one fixed size, is what confirms a small version of a pattern has not shrunk a piece below the 3/8 in cutoff.

Try this live on the free pattern with the Pattern Sizer tool, or see how much glass do I need for the area side of sizing.