How to Measure Room
Measure a Room

How to Measure a Room for Carpet

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 length and width in feet, the same way you would for flooring, but then check that measurement against your carpet’s roll width — usually 12 ft. If either dimension of the room exceeds the roll width, you’ll need a seam, and the amount of carpet you order depends on how the installer plans to lay out the pieces.

Step 1: Measure the room

Measure wall-to-wall for length and width, and include any closets the carpet will cover. For an irregular room, split it into rectangles first — see how to measure a room’s square footage for that process. Multiply length by width to get square feet, then divide by 9 to get square yards, since carpet is typically priced per square yard.

Example: A 15 ft × 12 ft room = 180 sq ft = 20 square yards.

Step 2: Check the room against the roll width

Standard broadloom carpet rolls are 12 ft wide (13’6” and 15 ft are also available from some manufacturers). Compare your room’s shorter dimension to the roll width:

  • Room fits within the roll width: no seam needed. Order length is straightforward — just make sure the roll’s width comfortably covers the room’s width.
  • Room is wider than the roll: a seam is required. Your installer will plan where it goes, but ordering typically needs extra material for the overlap and pattern/pile-direction matching at the seam — this is where the higher end of your waste allowance goes.

Step 3: Add a waste factor

Situation Recommended waste factor
Room fits within roll width, simple rectangle 10%
Room needs a seam, or has closets/jogs 15%
Patterned carpet needing pattern match at seams 15–20%

Step 4: Think about pile direction

Carpet pile has a direction (it looks and feels slightly different depending on which way you run your hand across it), and all pieces in a room should be laid with the pile running the same way — mismatched pile direction is visible as a subtle color/sheen difference between pieces. This is mostly your installer’s concern, but it’s worth confirming they’re accounting for it, especially in a room requiring a seam.

A note on padding

Carpet padding is measured and ordered the same way as the carpet itself (same square yardage), but it doesn’t need the same waste allowance for pattern matching — a straightforward 5–10% covers trimming and seams for padding.

Frequently Asked Questions

Why does carpet come in 12-foot widths?

12 ft (and sometimes 13'6" or 15 ft) is the standard roll width most broadloom carpet is manufactured and sold in. It's a manufacturing convention, not a rule you can choose around — if your room is wider than the roll, you'll need a seam somewhere.

How much extra carpet should you order for waste?

10–15% above your room's square footage is typical, covering pattern matching, seam overlap, and trimming around the room's edges. Rooms that need a seam, have a lot of closets or jogs, or use a patterned carpet should be closer to 15%.

Do you measure carpet in square feet or square yards?

Carpet is typically priced and sold by the square yard, but it's easiest to measure the room in square feet first (length x width) and then divide by 9 to convert to square yards, since square yards aren't an intuitive unit to measure directly with a tape measure.

Where should a carpet seam be placed in a room?

In the least-trafficked, least-visible area of the room — typically along a wall where furniture will sit, running in the same direction as the main light source (windows), which makes the seam far less visible than one running perpendicular to the light.

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