Measure a Room

A standard secondary bedroom is typically 132-150 sq ft (about 11x12 to 12x12.5 ft). A primary/master bedroom usually runs 200-250 sq ft, while most US building codes set a legal minimum of 70 sq ft for a habitable bedroom.

Measure the room's length and width in feet, then check them against your carpet's roll width (usually 12 ft) — rooms wider than the roll need a seam, which changes how much you should order.

Measure the room's square footage, then add a waste factor on top — 10% for straight-lay flooring, 15% or more for diagonal layouts or rooms with lots of angles.

Measure the room's length, width, and every doorway or hallway the furniture has to pass through, then leave at least 30-36 inches of walking clearance around anything you place.

Multiply the room's length by its width, both in feet, to get square feet. For an irregular room, split it into rectangles, find each one's square footage, and add them together.