Window Catio Calculator: Mesh, Roll Length and the Frame Cutting List

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Opens on the book's own cat and wall. Change any number to your own and press Calculate.

Box width mm; 3 ft = 914.4

Depth mm; 2 ft = 609.6

Height mm

Your window's width mm, outside the frame; optional

Your cats' weights kg, separated by commas

Mesh on

The roll

Roll width mm; 36 in = 914.4

Roll length ft

Roll price

Mesh opening mm; 1 in = 25.4

The frame and legs

Frame stock mm; a 2x2 is 38.1 square

Board length mm

Saw cut mm

Outside sill above the ground mm

Legs run up the box mm

Square door mm

Staples every mm along each edge

Enter the box and press Calculate.

The formula

Mesh area = front (w × h) + 2 sides (d × h) + top (w × d)
Roll used: lay each panel across the roll's width; it uses its other side's length. With a 36 in roll and a 36 in-high box: w + 3 × d
Frame: 4 uprights (h) + 4 width rails (w − 2 × stock) + 4 depth rails (d − 2 × stock). Legs = sill height + the lap up the box
Widest window = w − 2 × stock. Staples = all twelve edges ÷ the spacing, rounded up

The book's worked example, Chapter 9. A 3 × 2 × 3 ft box takes 2.5084 m² (27 ft²) of mesh and 2,743.2 mm (9 ft) of a 50 ft roll, leaving 41 ft. The frame is 9,144 mm of 2x2: each board gives an upright, a width rail and a depth rail (2,295 mm with the cuts). Legs of 1,060 mm come two to a board: 7 boards, 5 untreated and 2 pressure-treated. It fits a window up to 838.2 mm (33 in) wide.

Use untreated wood for everything inside the cat's reach and treated wood only for the legs below the floor. The book's mesh is 1 × 1 in, 16-gauge welded wire: openings of 25 mm, the size UK cattery standards require. Ground floor only, and keep the window screen out of the cat's way. Metric first, imperial beside it. Prices are illustrative US home-center prices from November 2026, shown without a currency sign; put in your own. Everything stays in your browser: no sign-up, nothing stored.