Ace the Interior Design IRC Test 2026 – Unleash Your Creative Flair Today!

When calculating the amount of carpet needed for a room, the total area is determined by multiplying the room's length by its width. In this case, for a room measuring 9 feet by 12 feet, the area is calculated as follows:

9 feet (length) × 12 feet (width) = 108 square feet.

However, when purchasing carpet, it's important to consider additional factors such as waste, seams, and any odd-shaped areas that may require more material. A common practice is to add an extra percentage of the total area to account for these variables, often leading to a recommendation of purchasing around 10% more than the calculated area.

If you were to apply this common practice, starting with 108 square feet and adding about 10%, you would arrive at approximately 119.8 square feet—rounded up to 120 square feet.

Therefore, the correct choice of 120 square feet takes into account not only the basic area of the room but also the practical consideration of purchasing enough carpet to ensure complete coverage and accommodate potential material loss during installation.