Carpet Calculator Footage. Carpet calculations require room shape and seam planning. Formula: Square Yards equals Room Area in Square Feet divided by 9. Carpet sold by square yard, measured in feet. Standard roll width 12 feet, some 15 feet. Calculate area: Length times Width. Example 12×15 ft room equals 180 sq ft equals 20 square yards. Add 10 percent waste equals 22 yards. Cost ranges: Budget carpet 1-3 dollars per sq ft installed, mid-grade 3-6 dollars, premium 6-12 dollars, luxury 12-25 dollars per sq ft. Includes carpet, padding, installation, removal of old. Padding essential: Thickness 3/8 to 1/2 inch standard. Density 6-8 pounds recommended. Cost 50 cents to 2 dollars per sq ft. Good padding extends carpet life 50 percent. Seam placement critical: avoid high-traffic walkways, place perpendicular to windows hides seams, match pile direction for uniform appearance. Pile direction runs one way, stroke carpet to find direction. Install pile toward main entrance makes carpet appear uniform. Stairs calculation different: measure tread depth plus riser height times number of steps. Standard step: 10 inch tread plus 8 inch riser equals 18 inches per step. Multiply by step count and width. 12 steps at 36 inches wide: 12 times 18 times 36 equals 7,776 sq inches equals 54 sq ft equals 6 square yards. Add 20 percent waste for stairs equals 7.2 yards. Stairs more complex, higher waste, costs 50-100 percent more per yard than flat rooms. Example whole house: 1,500 sq ft equals 167 square yards. Add 10 percent waste equals 184 yards. Cost at 5 dollars per sq ft: 7,500 dollars total. Breakdown: carpet 2,500, padding 750, labor 3,000, removal and disposal 500, transitions 250, stairs extra 500. Common mistakes: measuring in feet, buying in yards without converting, ignoring seam locations, skipping padding quality, forgetting closets, not accounting stairs separately. Pro tips: choose carpet based on traffic level, Berber for high traffic, plush for low, measure all closets separately, add transitions at doorways, use knee kicker for tight fit, roll carpet to confirm measurements. Carpet types: Loop pile (Berber) durable for traffic, cut pile soft and plush, patterned hides stains, frieze twisted fibers, saxony formal smooth. Fiber types: Nylon most durable, stain-resistant, expensive. Polyester soft, affordable, less durable. Olefin moisture-resistant, outdoors, least expensive. Wool natural, luxurious, very expensive. Nylon best for most homes balances durability and cost. Installation methods: Stretch-in traditional uses tack strips, removable, most common. Glue-down permanent, commercial, moisture-proof basements. Carpet tiles modular, replaceable, DIY-friendly. Costs: Removal old carpet 1-2 dollars per sq ft. Subfloor prep 2-4 dollars per sq ft if damaged. Moving furniture 50-200 dollars. Same-day installation premium 200-500 extra. Stairs hand-work premium 3-7 dollars per step. Transitions metal strips 10-30 each. Room shape affects waste: Rectangular rooms minimal waste 5-10 percent. L-shaped rooms 10-15 percent waste. Multiple small rooms 15-20 percent waste. Angled walls or bay windows 15-20 percent. Curved staircases 25 percent waste. Always round up to next full yard. FAQ: How much carpet for 10×12 room? 120 sq ft equals 13.3 square yards, buy 15 yards with waste, cost 450-1,000 dollars installed. Is padding necessary? Absolutely yes, extends life and comfort dramatically. What about seams? Unavoidable in large rooms, place away from traffic, perpendicular to windows. How long to install? Professional installs 500-800 sq ft per day. Can I install myself? Yes for carpet tiles, difficult for stretch-in requires special tools.