About the Carpet Calculator
This carpet calculator converts room measurements into the square yards that carpet is priced and sold by in the US, then estimates the full installed cost. Enter the length and width of up to three rooms, add a waste allowance for seams and trimming, and enter the price per square yard for carpet, padding and installation to see a complete budget.
It is useful when you are comparing quotes from flooring stores, budgeting a bedroom or whole-floor refresh, or checking whether a remnant is big enough. Because carpet comes off rolls that are usually 12 feet wide, the amount you pay for is always a little more than the floor area — the waste allowance accounts for seams, pattern matching and edges trimmed against walls.
If your prices are per square foot rather than per square yard, multiply them by 9 before entering them. Stairs, closets and hallways can be entered as an extra room using their measured length and width.
With the default inputs, the carpet to buy is 33.98 sq yd. Change any value above to recalculate instantly.
How to use the carpet calculator
- 1Measure each room’s length and width at the widest points, in feet.
- 2Enter up to three rooms (leave unused rooms at 0).
- 3Set the waste allowance — 10% for simple rooms, more for patterns.
- 4Enter carpet, pad and installation prices per square yard.
- 5Use the total square yards and cost to compare store quotes.
Formula and method
Each room’s area in square feet is its length times its width, and the rooms are added together. A waste allowance is applied because carpet is cut from rolls (usually 12 ft wide), so seams, pattern matching and trimming at walls consume extra material.
Dividing square feet by 9 converts to square yards, since one square yard is 3 ft × 3 ft. Carpet, pad and installation are each priced per square yard, so each cost is the ordered square yards times its price, and the total is their sum.
- L, W
- Room length and width (ft)
- waste%
- Allowance for seams and trimming
- 9
- Square feet per square yard
Worked examples
Living room plus bedroom
A 14 × 12 ft living room (168 sq ft) and an 11 × 10 ft bedroom (110 sq ft) total 278 sq ft. With 10% waste that is 305.8 sq ft or 33.98 sq yd, and at $38 per sq yd all-in the job costs about $1,291.
Large 20 × 15 ft family room
A 300 sq ft room with 10% waste needs 330 sq ft, which is 36.67 sq yd. At $30 carpet, $6 pad and $7 installation per sq yd, the total is about $1,577.
Three bedrooms with patterned carpet
Rooms of 144, 132 and 100 sq ft add to 376 sq ft. Patterned carpet needs about 15% waste, giving 432.4 sq ft or 48.04 sq yd, and at $30 per sq yd installed the total is about $1,441.
Frequently asked questions
How do I convert square feet to square yards of carpet?+
Divide square feet by 9, because a square yard is 3 ft by 3 ft. For example, a 12 × 15 ft room is 180 sq ft, which is 20 square yards before adding waste.
How much extra carpet should I buy?+
Most installers add about 10% for seams and trimming. Use 15–20% for patterned carpet that must be matched, rooms wider than the 12 ft roll, or irregular layouts with closets and angles.
How much does it cost to carpet a 12 × 12 room?+
A 12 × 12 room is 144 sq ft or 16 sq yd. With 10% waste and an all-in price of $38 per square yard (carpet, pad and install) the cost is about $670.
Is carpet pad priced separately?+
Often yes. Stores may bundle pad and installation into a promotional price, but many quote carpet, pad and labor separately. Enter each per square yard to see the true total.
How do I measure a room for carpet?+
Measure wall to wall at the longest and widest points, including into doorways where the carpet will end at a transition strip. Round each measurement up to the next half foot.