Carpet Calculator
Estimate carpet in square feet, square yards & total cost
🧶 Room & carpet details
Industry standard is about 10%. Use more for stairs, hallways, or rooms with lots of corners.
Last updated June 2026
Method: Carpet area = room area × (1 + waste %). Square yards = square feet ÷ 9 (since 1 sq yd = 9 sq ft). Cost = total area × price per unit. A 10% waste allowance is applied by default.
Included: Room area from length × width or a direct figure, an adjustable waste factor, conversion between square feet and square yards, and total material cost priced per square foot or square yard.
Not included: Carpet padding, tack strips, seam tape, installation labor, sales tax, and roll-width layout. Results are estimates, not a retailer quote.
Carpet calculator: how much carpet do you need?
Carpeting a 15 ft × 12 ft bedroom means covering 180 square feet - but you should not order exactly 180. Add the standard 10% waste allowance and you are buying about 198 square feet, which is roughly 22 square yards. At a typical mid-range price of $27 per square yard ($3 per square foot), that works out to around $594 for the carpet itself. This carpet calculator does that whole conversion - area, waste, square-yard math, and cost - in one step, so you can budget a room (or a whole house) before you ever set foot in a showroom.
The formula behind the numbers
There is no mystery to it - just three short steps:
Room area (sq ft) = length (ft) × width (ft) Carpet needed (sq ft) = room area × (1 + waste % ÷ 100) Square yards = carpet (sq ft) ÷ 9 Total cost = carpet area × price per unit The only number people stumble on is the ÷ 9. A yard is 3 feet, so a square yard is 3 ft × 3 ft = 9 square feet. Carpet has traditionally been sold by the square yard, which is why converting matters - a price that looks high per yard can be perfectly normal per foot, and vice versa.
A worked example, start to finish
Say you are recarpeting a living room that measures 20 feet by 16 feet.
- Area: 20 × 16 = 320 sq ft.
- With 10% waste: 320 × 1.10 = 352 sq ft.
- In square yards: 352 ÷ 9 ≈ 39.1 sq yd.
- Cost at $30/sq yd: 39.1 × $30 ≈ $1,173 for the carpet.
Notice the room is 16 feet wide but carpet rolls are usually 12 feet wide. Your installer will likely run a 12-foot strip down the length and seam a second piece alongside it - which is exactly why that 10% waste cushion exists. Skip it and you risk being short by a strip you cannot color-match later.
How to measure your room
- Measure the longest wall in feet for the length, then the longest perpendicular wall for the width. Measure to the baseboards, not the trim.
- Round up to the nearest few inches; it is cheaper to have a little extra than to come up short.
- Include closets and alcoves - measure each separately and add the square footage in.
- For L-shaped or irregular rooms, split the floor into simple rectangles, find each area, and add them together.
- For doorways, carry the carpet to the center of the door or into the next room's threshold, and add that small area.
- Sketch the room with measurements so you (or your installer) can plan where seams fall.
How to use this calculator
Enter your numbers and read the result instantly:
- Room size: type the length and width in feet, or switch to "Total area" if you already know the square footage.
- Waste: leave it at 10% for a simple room, or use the quick buttons (5/10/15/20%) for trickier layouts and stairs.
- Price: enter the carpet price and choose whether it is per square foot or per square yard - the calculator converts both ways.
The big number at the top is the total square footage to buy, with square yards and estimated cost right beneath it, plus a full line-by-line breakdown.
Who this calculator is for
- DIY homeowners pricing a single room before a store visit.
- Renovators and flippers budgeting flooring across several rooms at once.
- Landlords estimating turnover costs between tenants.
- Renters sizing area rugs or carpet tiles for a space.
- Anyone comparing quotes who wants to sanity-check an installer's square-yard estimate.
Key terms explained
- Square yard: a 3 ft × 3 ft area, equal to 9 square feet. The traditional unit for selling carpet.
- Waste factor (overage): the extra carpet, expressed as a percentage, ordered to cover trimming, seams, and roll-width mismatch. Usually 10%.
- Broadloom: carpet sold off a wide roll (commonly 12 ft) and cut to fit, as opposed to carpet tiles.
- Dye lot: a single dye batch; pieces from different lots can vary slightly in color, so buy all at once.
- Pile: the visible fibers of the carpet; pile direction affects how seams blend and how the carpet looks under light.
- Seam: where two pieces of carpet are joined, unavoidable in rooms wider than the roll.
Scenario 1: a standard bedroom
A 12 ft × 11 ft bedroom is 132 sq ft. With 10% waste that is about 145 sq ft, or roughly 16.1 square yards. At $25/sq yd the carpet runs about $403. Because the room is under 12 feet in both directions, a single roll width can cover it with minimal seaming - one of the simplest, lowest-waste jobs there is.
Scenario 2: a wide living room with a seam
An 18 ft × 14 ft living room is 252 sq ft. At 14 feet wide it exceeds the 12-foot roll, so a seam is required and 12-15% waste is wiser. At 15% that is about 290 sq ft (≈ 32.2 sq yd); at $32/sq yd the material is roughly $1,030. The extra waste pays for the seamed-in strip and a remnant for future repairs.
Scenario 3: a staircase
For a 13-step staircase, a common estimate is about 1.5-2 sq ft of carpet per step (tread plus riser). At 2 sq ft that is roughly 26 sq ft of finished area, but stairs generate heavy cutting and seaming, so apply 20% waste - about 31 sq ft. At $4/sq ft, expect around $125 in material before padding and labor. Stairs are labor-intensive, so installation often costs more than the carpet itself.
What changes the result the most
- Room dimensions: the biggest driver - area grows with both length and width.
- Roll width vs. room width: a room just over 12 feet wide forces a seam and pushes up waste.
- Waste percentage: the difference between 10% and 20% is real money on a large job.
- Price unit: mixing up per-foot and per-yard pricing can make a quote look 9× off - always confirm the unit.
- Room shape: corners, closets, and irregular outlines all add cuts and waste.
Practical tips before you order
- Always order about 10% extra (more for complex rooms). Running short means a second order from a possibly different dye lot.
- Keep a remnant for repairs and patches - it will match because it is from the same lot.
- Budget for padding and labor separately; the carpet is only part of the total project cost.
- Confirm the roll width with your retailer; it determines how seams fall and how much you truly need.
- Get a professional measure for big jobs - many retailers offer it free with purchase.
Limitations and assumptions
This is a planning estimate, not a retailer quote. Keep these in mind:
- It assumes a simple rectangular area; split irregular rooms into rectangles and add them.
- It does not model roll-width layout or exactly where seams fall - a pro measure can change the quantity.
- It excludes padding, tack strips, seam tape, installation, and sales tax.
- It does not account for pattern repeat, which can require significantly more carpet to match.
- Prices vary widely by fiber, brand, and region - use a real local quote for budgeting.
Related materials & tools
Carpet is one of several flooring and material estimates you might be running on the same project:
- To find the area of any space first, use the Square Footage Calculator.
- For volume-based materials like soil or concrete, the Cubic Yard Calculator handles the depth dimension.
- Pouring a subfloor or slab? The Concrete Calculator gives cubic yards.
- Landscaping the yard too? Try the Gravel Calculator and Mulch Calculator.
- Repainting the room before the new carpet goes down? Use the Paint Calculator.
⚠️ Common mistakes & edge cases
Ordering the exact room size
Buying precisely 180 sq ft for a 180 sq ft room leaves no margin for trimming, seams, or roll-width mismatch. Always add about 10% - running short means a new order from a different, possibly mismatched dye lot.
Confusing square feet with square yards
A "$27" carpet per square yard is only $3 per square foot - a 9× difference. Mixing the units wrecks your budget. Confirm which unit the price uses, and remember: sq yd = sq ft ÷ 9.
Ignoring the 12-foot roll width
A room just over 12 feet wide needs a seamed second strip, which adds waste you did not plan for. Rooms wider than the roll should use 12-15% waste, not 10%.
Forgetting padding and installation
This estimate is the carpet material only. Cushion, tack strips, seam tape, and labor are billed separately and can rival the cost of the carpet itself - especially on stairs. Budget for them up front.
❓ Frequently asked questions
How do I calculate how much carpet I need?
Multiply the room's length by its width in feet to get the area in square feet, then add a waste allowance (about 10%) for trimming, seams, and offcuts. To convert to square yards - the unit carpet is often priced and sold in - divide the square footage by 9. For example, a 15 ft x 12 ft room is 180 sq ft; with 10% waste that's 198 sq ft, or about 22 square yards.
Why divide by 9 to get square yards?
There are 3 feet in a yard, so a square yard is 3 ft x 3 ft = 9 square feet. To convert any area from square feet to square yards, divide by 9. To go the other way, multiply square yards by 9. Carpet has traditionally been sold by the square yard, though many U.S. retailers now price it per square foot.
How much waste should I add for carpet?
Around 10% is the standard allowance for a simple rectangular room. Add more - 15% to 20% - for rooms with lots of corners, closets, bay windows, hallways, or stairs, and for patterned carpet that needs to be matched at the seams. Waste covers trimming, seam overlaps, and the fact that carpet comes on fixed-width rolls (usually 12 feet) that rarely divide evenly into your room.
How wide does carpet come?
Most broadloom carpet is manufactured on rolls 12 feet wide; some styles also come in 13 ft 6 in or 15 ft widths. Roll width is the main reason you almost always buy more than the exact room area: a 10-foot-wide room still needs a 12-foot-wide piece, and the extra 2 feet becomes waste or fill for closets and seams.
Is carpet priced per square foot or per square yard?
Both are common in the United States. Big-box stores often quote per square foot, while many flooring specialists still quote per square yard. They describe the same product - just divide the square-yard price by 9 to get the per-square-foot price (a $27/sq yd carpet is $3/sq ft). This calculator lets you enter either and shows you both.
Does this calculator include padding and installation?
No. It estimates the carpet material itself in square feet, square yards, and total material cost. Carpet padding (cushion), tack strips, seam tape, and labor are billed separately. As a rough guide, padding adds roughly $0.50-$1.50 per square foot and professional installation a few dollars per square foot, but get a local quote for accurate numbers.
How do I measure an irregular or L-shaped room?
Break the space into simple rectangles, calculate the square footage of each, then add them together before applying your waste percentage. For closets and alcoves, measure them separately and include them. When in doubt, measure to the widest points and round up - it is far cheaper to have a little extra than to come up short on a dye lot you cannot rematch.
What is a dye lot and why does it matter?
A dye lot is a single production run of carpet dyed at the same time. Carpet from different dye lots can vary slightly in color, so a patch bought months later may not match. This is the main reason to order all the carpet for a project at once - and to keep a leftover remnant for future repairs - rather than buying the bare minimum.
How accurate is this carpet estimate?
It is a solid planning estimate for budgeting and comparison shopping. The real quantity depends on roll width, room shape, where seams fall, and your installer's layout, so a professional measure may differ. Treat the result as a close starting point, then confirm with your retailer or installer before placing the order.
Can I use this for stairs or hallways?
Yes, but bump up the waste percentage. Stairs and long hallways generate a lot of cuts and seams, so 15-20% waste is more realistic than 10%. For stairs, a common rule of thumb is about 1.5 to 2 square feet of carpet per step (tread plus riser); measure your run and treads, total the area, then add the higher waste factor.
💡 Good to know
Carpet rolls are usually 12 feet wide
That fixed width is the main reason you almost always buy more than the bare room area. A 10-foot-wide room still needs a 12-foot piece, and a room over 12 feet wide needs a seam. Plan layout around the roll, not just the floor area.
Buy it all at once - dye lots matter
Carpet dyed in separate batches can differ slightly in color. Order the full amount in one go and keep a leftover remnant, so any future patch or repair comes from the same dye lot and blends in.
10% extra is the sweet spot
For a simple rectangular room, a 10% waste allowance covers trimming and seams without overbuying. Step it up to 15-20% for stairs, hallways, patterned carpet, or rooms full of corners and closets.
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