Carpet Calculator
Calculate how much carpet and padding you need for any room. Get estimates in square feet, square yards, and linear feet with cost estimates.
How to Calculate Carpet for a Room
To estimate carpet for a room, start by measuring the length and width of the space in feet. Multiply these together to get the total room area in square feet. Add a waste factor of 10-20% to account for seams, pattern matching, and cutting around obstacles. Convert to square yards by dividing the total area by 9, since carpet is typically priced per square yard. To determine how many linear feet of carpet you need from a roll, divide the total carpet area by the roll width (either 12 ft or 15 ft).
Carpet Roll Widths
| Roll Width | Best For | Notes |
|---|---|---|
| 12 ft | Most rooms, hallways, bedrooms | Standard width; widely available in all styles and colors. Works well for rooms up to 12 ft wide with no seams. |
| 15 ft | Larger rooms, open floor plans | Reduces or eliminates seams in wider rooms. Less common; fewer style options. Ideal for rooms 12-15 ft wide. |
Understanding Carpet Waste
A waste factor of 10-20% is standard when ordering carpet. This extra material accounts for several real-world installation needs: seams between carpet strips must overlap slightly and be trimmed for a clean join; patterned carpet requires alignment between strips, consuming extra material; irregularly shaped rooms, closets, and doorways create odd cuts that generate waste; and slight measurement errors or wall irregularities mean you need a buffer. For simple rectangular rooms, 10% is usually sufficient. For L-shaped rooms, patterned carpet, or rooms with many obstacles, 15-20% is recommended.
Tips for Buying Carpet
- Always order all your carpet from the same dye lot to avoid color variation between rolls.
- Buy slightly more than your estimate — running short mid-installation is costly and may result in a dye lot mismatch.
- Consider traffic patterns when choosing carpet fiber: nylon is the most durable, polyester is the most stain-resistant, and wool is the most luxurious. If you are considering tile or other hard flooring instead, compare costs before committing.
- Check the carpet warranty — many warranties require professional installation and a specific padding thickness.
- After carpet installation, finish the room with baseboard trim to create a clean edge where the carpet meets the wall.
- Request carpet samples and view them in your room under both natural and artificial light before committing.
- Ask about carpet roll width availability — not every style comes in both 12 ft and 15 ft rolls.
- Comparing flooring options? See our laminate vs hardwood comparison.
Frequently Asked Questions
A 12x12 room has 144 square feet of floor area, or 16 square yards. With a standard 10% waste factor, you would need about 158 sq ft (17.6 sq yards) of carpet. Using a 12-ft wide roll, you would need approximately 13.2 linear feet of carpet. If you are also installing padding, you would need the same 17.6 square yards of padding material.
Carpet is traditionally priced and sold by the square yard in the United States. One square yard equals 9 square feet (a 3 ft by 3 ft area). However, many retailers now also list prices per square foot for easier comparison. When measuring your room, it is easiest to measure in feet and then divide the total area by 9 to convert to square yards. This calculator provides both measurements for your convenience.
Carpet padding (also called underlay or cushion) is a layer of material installed between the subfloor and the carpet. It provides cushioning underfoot, extends the life of the carpet by absorbing impact, improves insulation, and reduces noise. Nearly all wall-to-wall carpet installations require padding. Most carpet warranties are void if the carpet is installed without proper padding. Standard padding thickness is 7/16 inch with a density of 6 to 8 pounds for residential use.
For a DIY carpet installation in a typical 12x12 room (16 sq yards), expect to spend $240 to $960 on carpet ($15 to $60 per sq yard), $48 to $128 on padding ($3 to $8 per sq yard), and $15 to $40 on tack strips. You will also need a knee kicker, carpet knife, and seam tape, which can be rented for about $30 to $50 per day. Total DIY cost for a 12x12 room is typically $300 to $1,150 depending on carpet quality, compared to $600 to $2,000 or more for professional installation.
Installing new carpet over existing carpet is generally not recommended. The old carpet traps moisture and creates an environment for mold and mildew growth. The uneven surface causes the new carpet to wear unevenly and develop lumps. It also doubles the thickness, making doors stick and transitions awkward. Most carpet warranties require installation over a clean, smooth subfloor with approved padding. For best results, remove the old carpet and padding, inspect and repair the subfloor, and install fresh padding before laying the new carpet.