Filing Cabinet Size Calculator

The most common commercial size is the 4-drawer vertical letter cabinet: 52 inches high x 15 inches wide x 25 inches deep (HON 510 class). A 4-drawer lateral cabinet, 36 inches wide, is typically 52.5 inches high x 36 inches wide x 18.75 inches deep (Hirsh HL8000 class). Two-drawer verticals are about 28.375 inches high, three-drawer units 40 inches, and five-drawer verticals about 61.375 inches. Individual models vary by roughly an inch, so always check the spec sheet before planning a tight fit.

A legal vertical cabinet is 3 inches wider than the letter version: 18 inches wide versus 15 inches, at the same drawer count and height. Legal paper is 14 inches long (versus 11 inches for letter), so a legal vertical cabinet also needs at least 25 inches of depth; 18-inch-deep vertical cabinets are letter-only. Lateral cabinets take both paper sizes side-to-side in the same drawer.

Per drawer, a 36-inch lateral gives you about 33 inches of side-to-side filing length, versus 23.5 inches of front-to-back filing in a 25-inch-deep vertical drawer. So one lateral drawer holds roughly 40% more sheets than one vertical drawer. But vertical cabinets use less floor space: a 4-drawer vertical letter cabinet has a footprint of about 2.6 square feet, while a 36-inch lateral needs about 4.7 square feet.

A 25-inch-deep vertical drawer provides 23.5 filing inches. At 250 sheets per inch for 20-lb bond paper and 80% usable fill (folders and followers take space), that is 23.5 x 250 x 0.8 = 4,700 sheets of letter paper per drawer, or about 9.4 reams. A full 4-drawer letter cabinet therefore holds about 18,800 sheets, roughly 37.6 reams.

At 4,700 usable sheets per drawer (25-inch-deep vertical, 20-lb letter paper, 80% fill), 10,000 sheets need 10,000 / 4,700 = 2.13 drawers, so a 3-drawer cabinet is the right size. Use the drawers-needed calculator above with your own paper weight and fill percentage for an exact answer.

Buy 25 inches deep (or 26.5 inches) if you ever file legal-size paper: legal sheets are 14 inches long and need the extra depth plus room for the follower. An 18-inch-deep vertical cabinet is letter-only, with about 16.5 filing inches per drawer versus 23.5 inches in a 25-inch-deep cabinet. If floor space is tight and you only file letter paper, the 18-inch depth saves 7 inches of room depth.

Paper is heavier than people expect. A full 4-drawer letter cabinet at 80% fill holds about 18,800 sheets; at 0.01 lb per sheet of 20-lb letter paper that is 188 lb of paper plus roughly 85 lb for the steel cabinet, about 273 lb total. A full 5-drawer 36-inch lateral can exceed 500 lb. Put heavy cabinets on ground floors or check floor loading, and anchor tall units against tipping.

Divide the filing length by your folder thickness. A 25-inch-deep vertical drawer has 23.5 filing inches; at a typical 1/4 inch per hanging folder, that is 23.5 / 0.25 = 94 folders per drawer, or 376 folders in a 4-drawer cabinet. A 36-inch lateral drawer has 33 inches of side-to-side filing, about 132 folders per drawer at the same thickness.

Plan for the cabinet depth plus one full drawer extension in front, because drawers open on full-extension slides. A 25-inch-deep vertical cabinet needs about 50 inches (just over 4 feet) of clear room depth. Width-wise, leave the cabinet width plus a couple of inches: 15-inch letter verticals need about 18 inches of wall, 36-inch laterals about 39 inches. For example, a 10 ft wall fits 8 vertical letter cabinets (15 inches wide each), while a 25-inch-deep cabinet needs about 50 inches of clear room depth.

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