How much carpet do I need?

Priced by the yard, cut by the roll

Carpet is quoted in square yards but it comes off a roll of fixed width, almost always 12 feet, sometimes 15. That mismatch is the whole difficulty. Your room might be 180 square feet, which is 20 square yards, but what you actually buy is a length cut off a 12 foot wide roll — and if the room is wider than the roll, you need more than one strip.

A room narrower than the roll width is the easy case: one strip, cut to the room length, and the leftover along one edge is trim. A room wider than the roll means a seam, and the second strip is rarely used efficiently. That is why the linear figure here can look generous next to the bare area.

Two things a calculator cannot decide for you. Pile direction: every strip must run the same way, or the two pieces will look like different colours under the same light. This is the single most common carpet mistake, and it cannot be fixed after the fact. And seam placement: a seam belongs where traffic and sightlines are lowest, never across a doorway.

The figures here do not include underlay, tack strip or the extra few inches most fitters want on every edge for stretching. Take the square yards to price the job and the linear feet to sanity-check a quote, then let the fitter do their own measure before anything is cut.