BuildCalc Pro

Drywall Calculator

Calculate the number of drywall sheets and accessories needed for any room based on dimensions.

How to Use This Calculator

1. Select Imperial or Metric. 2. Enter room length, width, and ceiling height. 3. Choose sheet size (4×8 standard or 4×12 for fewer joints). 4. Enter number of doors and windows to subtract. 5. Toggle ceiling inclusion if drywalling the ceiling. 6. Optionally add cost per sheet. 7. Click "Calculate" for a complete materials list. Tip: A 10% waste factor is automatically included. For textured ceilings, consider adding 15% extra.

Complete Guide to Estimating Drywall for Your Project

Drywall (also called sheetrock or gypsum board) is the most common wall and ceiling finish material in residential construction. Accurate estimation prevents costly overages and ensures your project stays on schedule.

Standard drywall sheets come in 4x8-foot and 4x12-foot sizes. The 4x12 sheets reduce the number of joints and are preferred for rooms with 9-foot or higher ceilings. Sheet thickness is typically 1/2-inch for walls and 5/8-inch for ceilings and fire-rated applications.

To estimate drywall, calculate the total wall area by multiplying the room perimeter by ceiling height. Subtract door and window openings. If including the ceiling, add the floor area. Divide the total area by the sheet size (32 sq ft for 4x8 or 48 sq ft for 4x12) and add 10% for waste.

Beyond the sheets themselves, you need joint tape (one roll per 7-8 sheets), joint compound (one 4.5-gallon box per 8-10 sheets), and screws (approximately 32 screws per 4x8 sheet). Budget about $0.50-$0.70 per square foot for these accessories.

Drywall costs $10-$15 per sheet for standard 1/2-inch, or $0.30-$0.50 per square foot. Professional installation runs $1.50-$3.00 per square foot including taping and finishing. The finishing process (mudding, taping, sanding) requires 3 coats and is often the most time-consuming step.

Frequently Asked Questions

How many sheets of drywall for a 12x12 room?

A 12x12 room with 8-foot ceilings needs about 18 sheets of 4x8 drywall for walls (after subtracting a door and two windows) plus 5 sheets for the ceiling, totaling approximately 23 sheets including 10% waste.

Should I use 4x8 or 4x12 drywall sheets?

4x12 sheets are better for rooms with standard 8-foot ceilings because they cover wall height with fewer horizontal joints. They are heavier and harder to handle but produce a smoother finish. 4x8 sheets are easier for DIY work.

How much does drywall installation cost?

Drywall installation costs $1.50-$3.00 per square foot for hang, tape, and finish. For a 12x12 room (walls and ceiling), expect $600-$1,200 total. DIY drywall hanging saves about 50% but requires significant skill for a quality finish.

What thickness drywall do I need?

1/2-inch is standard for walls, 5/8-inch for ceilings (resists sagging between joists). Use 5/8-inch Type X for fire-rated assemblies (garage walls, furnace rooms). 1/4-inch flexible drywall is used for curved walls.