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. |
How to Measure a Room for Carpet
To measure a room for carpet, use a tape measure to record the room's longest length and widest width, and always measure into closets, doorways, and alcoves — carpet needs to extend to the midpoint of each doorway, and closets are carpeted along with the room. Measure at the widest points even if the room narrows, because carpet is cut from a rectangular piece and the installer trims away the excess. Add 3 to 4 inches per wall to your measurements so there is enough material to trim for a clean edge against every wall; walls are rarely perfectly straight, and a tight cut leaves no room for error.
Keep roll width in mind as you measure. Most carpet comes on 12-foot rolls, so a room wider than 12 feet will need a seam — and where that seam falls affects both appearance and how much carpet you need. Plan seams to run away from main sightlines and traffic paths when possible. For multi-room jobs, measure each room separately rather than lumping the areas together: each room is cut from the roll individually, and measuring room by room captures the real cutting layout, the seams, and the waste that a single combined square-footage number would hide.
Square Feet to Square Yards Conversion
Carpet is often priced by the square yard, while rooms are measured in square feet. To convert, divide square feet by 9 (one square yard is a 3 ft × 3 ft area, or 9 sq ft): square yards = square feet ÷ 9.
| Square Feet | Square Yards |
|---|---|
| 100 sq ft | 11.1 sq yd |
| 150 sq ft | 16.7 sq yd |
| 200 sq ft | 22.2 sq yd |
| 300 sq ft | 33.3 sq yd |
| 400 sq ft | 44.4 sq yd |
| 500 sq ft | 55.6 sq yd |
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.
Measure the room's length and width in feet at the longest and widest points, including closets and doorways, then multiply the two numbers to get the square footage. Add a 10-20% waste factor for seams, trimming, and pattern matching. To get square yards, divide the total by 9. For example, a 15x12 room is 180 sq ft; with 10% waste that is 198 sq ft, or 22 square yards of carpet. Measure multi-room jobs room by room, since each room is cut from the roll separately.
There are 9 square feet in one square yard of carpet. A square yard measures 3 feet by 3 feet. To convert a room measurement from square feet to square yards, divide the square footage by 9 — a 144 sq ft room is 16 square yards. This conversion matters because carpet is traditionally priced per square yard in the United States, even though rooms are usually measured in feet.
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.