Carpet Calculator - Square Yards & Cost Estimator

How to measure for carpet

Carpet is sold by the square yard (1 sq yd = 9 sq ft). Measure each room’s length and width in feet, multiply to get square footage, then divide by 9 to convert to square yards.

Square yards = (Length ft × Width ft) ÷ 9

Waste factor

Always add 10–15% to your measured area to account for:

• Pattern matching: patterned carpets require aligning the repeat at seams, wasting 10–20% extra.
• Irregular rooms: L-shaped or angled rooms produce offcuts that cannot be reused.
• Carpet roll width: carpet typically comes in 12-foot or 15-foot wide rolls. Room dimensions that don’t divide evenly into roll widths create unavoidable waste.

Don’t forget carpet padding

Carpet padding (underlay) adds cushioning, insulation, and extends carpet life. Order padding at the same square yardage as your carpet. Standard padding is 7/16” thick at 6–8 lb density for most residential use. Higher density (8+ lb) is better for heavy-traffic areas.

Measuring irregular rooms

For L-shaped rooms, break the space into two rectangles, calculate each separately, and sum the areas. For rooms with alcoves or bump-outs, measure the largest bounding rectangle and then subtract any areas that will not be carpeted (e.g., a closet with a different floor covering). Always round up when in doubt - it is much harder to add carpet after installation than to return a small unused remnant.

Stair carpet calculation

For stairs, measure the width of the stair, the tread depth, and the riser height. Each step requires: width × (tread depth + riser height). Multiply by the number of stairs and add at least 10% for waste and tucking. Most residential stairs need a strip approximately 27–32 inches wide × 18–22 inches per step (tread + riser combined).

Carpet types