Drywall Calculator
Calculate exactly how many sheets of drywall you need plus tape and joint compound. Enter room dimensions, get instant results with cost estimate. Metric and imperial.
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How to Calculate Drywall by Square Footage
The formula for calculating drywall is straightforward: measure all wall surfaces and the ceiling, total the square footage, then divide by the sheet size. Here's the step-by-step process:
Step 1: Measure the perimeter of the room (add all wall lengths together). Step 2: Multiply perimeter by ceiling height to get total wall area. Step 3: Add ceiling area (length x width) if you're drywalling the ceiling. Step 4: Subtract openings — deduct 50% of window area and 100% of door openings. Step 5: Divide by sheet size (32 sq ft for 4x8 sheets) and round up. Step 6: Add 10-15% for waste.
Drywall Cost Estimator
Total drywall cost depends on materials, labor, and room complexity. For materials only: standard 1/2-inch sheets run $12-$18 each, plus $15-$25 for a box of joint compound, $5-$8 per roll of tape, and $8-$12 for a box of screws. A typical bedroom (12x12 ft) costs $250-$400 in materials for a complete job including ceiling.
For professional installation, expect $1.50-$3.50 per square foot all-in (hanging + taping + finishing). Level 4 finish (ready for paint) costs more than Level 3 (ready for heavy texture). Factors that increase cost: high ceilings, multiple corners, arches, and demolition of old material. Get 3 quotes and verify the finish level included.
Drywall Sheets Needed Per Room Size
Here are quick estimates for common room sizes with 8-foot ceilings, including walls and ceiling, with 10% waste: A 10x10 room needs about 14 sheets. A 10x12 room needs about 15-16 sheets. A 12x12 room needs 17-18 sheets. A 12x14 room needs 19-20 sheets. A 14x16 room needs 24-25 sheets. These assume standard 4x8 sheets and one door plus one window per room.
Drywall vs Sheetrock: What's the Difference?
Sheetrock is simply USG Corporation's trademark for their brand of gypsum drywall panels. The terms are used interchangeably by contractors and homeowners. Other brand names include CertainTeed, Georgia-Pacific (ToughRock), and National Gypsum (Gold Bond). All perform identically for standard residential applications. When shopping, compare price and availability rather than brand — the manufacturing standards are the same across all major producers.
Tips for Ordering Drywall
Always round up to whole sheets — half sheets create unnecessary joints. Buy 1-2 extra sheets beyond your calculated waste factor for mistakes. If you're doing multiple rooms, measure all of them and place one order to save on delivery fees (usually $50-$100 for a truck delivery). Store sheets flat and off the ground on 2x4 supports to prevent warping before installation.
Frequently Asked Questions
How many sheets of drywall do I need per square foot?
One standard 4x8-foot sheet covers 32 square feet. Divide your total wall and ceiling area by 32 to get the base number of sheets, then add 10-15% for waste from cuts, corners, and openings. For example, a room with 500 sq ft of wall area needs about 17-18 sheets.
How do I calculate drywall by square footage?
Measure each wall (width x height) and add them together. For ceilings, multiply room length by width. Add wall area + ceiling area to get total square footage. Subtract 50% of window areas and 100% of door openings, then divide by your sheet size (32 sq ft for 4x8, 40 sq ft for 4x10).
What is the difference between drywall and sheetrock?
Sheetrock is a brand name by USG Corporation for their gypsum drywall panels. Drywall (also called plasterboard or gyprock) is the generic term. They are functionally the same product. All Sheetrock is drywall, but not all drywall is Sheetrock — similar to how Kleenex is a brand of tissue.
How much does drywall cost per sheet and per square foot?
Standard 1/2-inch 4x8 sheets cost $12-$18 each ($0.38-$0.56 per sq ft for materials). Moisture-resistant (green board) costs $14-$20, fire-rated (Type X) $15-$22. With professional installation (hanging, taping, finishing), total cost is $1.50-$3.50 per square foot, or $2,000-$5,000 for a typical room.
How much joint compound and tape do I need?
Plan for about 3.5 lbs (1.6 kg) of joint compound per 100 sq ft of drywall, and one roll of paper tape per 100-120 sq ft. A 20 kg (44 lb) box of compound covers roughly 13-15 m² (140-160 sq ft). For a 12x12 room, budget 2-3 rolls of tape and one box of compound.
What size drywall sheets should I use?
Use 4x8-foot (1200x2400mm) sheets for standard 8-foot ceilings. For 9 or 10-foot ceilings, use 4x10 or 4x12 sheets hung horizontally to eliminate a horizontal butt joint. Use 1/2-inch (12.5mm) thickness for walls, 5/8-inch (15.9mm) Type X for ceilings, and 1/4-inch (6.4mm) for curved surfaces.
How much does it cost to drywall a 12x12 room?
A 12x12-foot room with 8-foot ceilings has roughly 528 sq ft of surface area (walls + ceiling). Materials cost $250-$400 (16-17 sheets, tape, compound, screws). Professional installation adds $800-$1,800 depending on your area and finish level. Total DIY cost is typically $300-$500.
How do I estimate drywall labor costs?
Professional drywall labor typically runs: hanging $0.75-$1.25/sq ft, taping/mudding $0.50-$1.00/sq ft, sanding/finishing $0.30-$0.50/sq ft. Total labor is $1.50-$2.75/sq ft. A 1,500 sq ft house interior costs $3,000-$6,000 for professional installation. Most jobs take 3-5 days.
How many screws do I need for drywall?
Use approximately 28-32 screws per 4x8 sheet. Screws should be placed every 12 inches along edges and every 16 inches in the field (center of sheet). For a room with 16 sheets, budget 450-500 drywall screws. Use 1-1/4 inch screws for 1/2-inch drywall on wood studs.
Should I add extra drywall for waste?
Yes. Add 10% for simple rectangular rooms and 15% for rooms with multiple windows, doors, closets, or angles. The waste comes from cutoffs around outlets, windows, and corners that are too small to reuse. It's always cheaper to buy one extra sheet upfront than to make a return trip to the store.