Carpet Calculator
Estimate carpet in square feet and square yards from room size, roll width, and waste. Compare layouts, add rooms, and see if a seam may be required — in your browser.
Results are planning estimates. Real installs depend on doors, closets, pile direction, pattern repeat, and the installer’s seam plan. 10% waste is a starting point, not a rule.
How much carpet do I need?
For a rectangular room, multiply length by width to get square feet. Divide by 9 for square yards (1 square yard = 9 square feet), then add a waste allowance. Because broadloom carpet comes on a fixed-width roll — usually 12 ft in the US — the amount you actually buy can be larger than the floor area if a second strip and a seam are required.
A 12 × 15 ft room is 180 sq ft, or 20 sq yd. On a 12 ft roll with 10% waste, this calculator estimates 22 sq yd and no seam. Hard-surface rooms belong on the Flooring Calculator.
What you can use this carpet calculator for
- Estimate how much carpet you need for a bedroom, living room, hallway, or several rooms
- Convert room measurements to square feet and square yards
- Add a waste allowance you can change (5%, 10%, 15%, 20%, or custom)
- See how a 12 ft or 15 ft roll changes linear feet and whether a seam may be required
- Check a retailer or installer quote before you order from one dye lot
How to use the carpet calculator
- Choose US or metric.
- Enter the room length and width. Open a common room size only if you want a starting point.
- Confirm 12 ft or 15 ft roll width. Most US carpet is 12 ft.
- Leave extra-for-cuts at 10% unless the room is patterned or oddly shaped.
- Read square yards to buy. Add another room only if you have a hallway, closet, or L-shape.
- Optional: open extra options for layout, padding, a custom roll, or a cost check from your quote.
How the carpet calculation works
Floor area is length × width. Square yards = square feet ÷ 9. That area-only number is useful for talking about the room. It is not always what you buy.
Broadloom is cut from a roll of fixed width. This tool tries both directions the carpet can run, counts whole strips with strips = ceil(cross dimension ÷ roll width), then estimates roll length as strips × run length. Carpet to buy is that roll length × roll width, then multiplied by (1 + waste%). Auto keeps the direction that uses less material. That is an estimate — doors, closets, pattern repeat, and pile direction can change a real install.
| Floor area | Length × width |
|---|---|
| Square yards | Square feet ÷ 9 |
| Strips | Round up (room width across the roll ÷ roll width) |
| Carpet to buy | Strips × run length × roll width × (1 + waste%) |
Square feet vs square yards
You usually measure a room in feet, so the first number you get is square feet. US carpet is still often quoted per square yard. One square yard is exactly 9 square feet — a 3 ft by 3 ft square. A 180 sq ft room is 20 sq yd before waste. If a showroom quotes per square foot, convert so you are comparing the same unit: $3.50 / sq ft is $31.50 / sq yd for the same goods.
Carpet rolls, waste, and seams
Broadloom comes off a bolt, most often 12 ft wide in US homes, sometimes 15 ft. If both room sides are larger than the roll, you need a second strip and a seam. Waste is not only “a little extra.” Leftover roll width, cuts at walls, closets, and pattern matching all add material. 10% is a reasonable start for a simple rectangle. Patterned goods and broken floor plans often need 15–20%. This page will not invent a stair takeoff — stairs need tread, riser, and winders measured separately.
Carpet calculator examples
All three match this page’s engine: 12 ft roll, 10% waste, Auto layout.
| Room | Floor | Carpet to buy |
|---|---|---|
| 12 × 15 ft | 180 sq ft · 20 sq yd | 22 sq yd · 16.5 linear ft · no seam |
| 12 × 12 ft | 144 sq ft · 16 sq yd | 17.6 sq yd · 13.2 linear ft · no seam |
| 15 × 20 ft | 300 sq ft · 33.3 sq yd | 44 sq yd · 33 linear ft · seam likely |
The 15 × 20 living room is why roll width matters. Area plus 10% is about 36.7 sq yd. On a 12 ft roll you still need two strips, so this calculator estimates 44 sq yd. A 15 ft roll for the same room estimates 36.7 sq yd and no seam.
Common carpet-planning mistakes
- Measuring baseboard-to-baseboard instead of wall-to-wall, then coming up short at the tack strip.
- Treating square feet as square yards. Divide by 9, or you will order about nine times too little.
- Ordering the floor area only and ignoring roll width. A second strip is leftover material you still pay for.
- Using 0% waste on a patterned carpet or an L-shaped room.
- Rounding down linear feet. Retailers cut from the roll; short orders do not stretch.
- Mixing dye lots. Buy the full estimate in one order.
- Rotating a remnant so the pile runs the other way. The seam will show.
Different ways people search for this
A carpet calculator, carpet estimator, or “how much carpet do I need” search is the same job: square feet, square yards, waste, and roll planning. Carpet tile counts and stair runners are different takeoffs. LVP and laminate carton math belongs on the flooring page. This page does not have a separate cost-only URL — optional prices here are only a budget check on the quantity you already calculated.
Related calculators
- Flooring Calculator for LVP, laminate, or hardwood cartons in dry rooms.
- Tile Calculator for ceramic or porcelain tile counts and boxes.
- Paint Calculator for wall paint in the same rooms after the carpet is in.