Carpet Calculator
Estimate carpet area and costs for rectangular rooms, with optional roll-width planning and a transparent waste allowance.
Estimated Result
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How to Use the Carpet Calculator
Enter one to thirty rectangular rooms in feet or meters. Choose an area-only estimate or a roll width in feet. Enter waste (10% by default), carpet price and an optional installation rate, selecting square feet or square yards separately. Results update immediately; Reset restores the 12 × 15 ft example.
Formula and Explanation
Floor area = Σ(length in ft × width in ft) Square yards = square feet / 9 Area with waste = floor area × (1 + waste / 100) For each orientation: strips = ceil(room width / roll width) Cut length per strip = room length × (1 + waste / 100) Roll purchase = strips × cut length × roll width Material cost = purchase area × matching price per area Installation = net floor area × matching installation rate
The roll estimate tests cuts along either room dimension and chooses the smaller purchase area for each room. All cuts in one room use the same direction, with full-width parallel strips and a narrower final strip trimmed as needed. Offcuts are not shared between rooms. Waste is applied once by extending each cut length; it is not added again after roll rounding. Without a roll width, material pricing uses area with waste. Installation pricing uses net floor area, not purchased offcuts.
This is a rectangular-room estimate, not a professional cutting plan. Seams, pile direction across adjoining rooms, pattern repeats, stairs, irregular shapes and installer layout can change material requirements. Different rooms may choose different orientations here; a continuous pile direction can require more carpet. Supplier cut-length increments, minimum orders, tax, delivery, padding and removal are excluded. Limits: 30 rooms, dimensions up to 1,000 ft, 0–100% waste, 1–30 ft roll widths and rates up to $1,000,000 per selected area unit.
Worked Example
A 12 × 15 ft room has 180 sq ft, or 20 sq yd. At 10% waste the area allowance is 198 sq ft, or 22 sq yd. With area-only pricing at $3/sq ft, material costs $594. Installation at $9/sq yd costs $180, totaling $774. A 12 ft roll uses one 16.5 ft cut including the same allowance, also 198 sq ft. A 10 × 10 ft room on that roll needs one 11 ft cut, purchasing 132 sq ft rather than merely 110 sq ft.
Frequently Asked Questions
Why is roll quantity larger than area with waste?
Whole roll widths leave trimmed material. The calculator compares both rectangular orientations but does not reuse offcuts or optimize a professional seam layout.
Is waste counted twice with a roll?
No. Each strip length receives the allowance once. The resulting full-width area is the purchase quantity used for material cost.
Can carpet and installation use different price units?
Yes. Each rate is converted independently: divide its square-foot basis by nine when the entered rate is per square yard. Installation uses net floor area.
Can I enter meters or several rooms?
Yes. Meters convert using exactly 0.3048 meters per foot. Room areas and separate roll estimates are summed; roll widths always remain in feet.
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