Drywall Calculator

This drywall calculator helps you estimate how many sheets of drywall (also called sheetrock or gypsum board) you need for your project. Simply enter the dimensions of each wall and optionally include ceiling coverage to get an accurate materials estimate including joint compound and tape.

Drywall sheets come in two standard sizes: 4x8 feet (32 sq ft) and 4x12 feet (48 sq ft). The 4x8 sheets are easiest to handle for DIY projects and fit standard 8-foot ceilings perfectly. The 4x12 sheets reduce the number of seams on longer walls and are preferred by professionals for faster installation and a smoother finish.

The waste factor accounts for material lost to cuts, damaged pieces, and fitting around obstacles. A 10% waste factor is standard for simple rectangular rooms. Choose 15% for rooms with multiple corners or angles, and 20% for complex layouts, cathedral ceilings, or if this is your first drywall project.

Standard interior doors measure approximately 3x7 feet (21 sq ft) and standard windows about 3x5 feet (15 sq ft). These deductions are averages - if your openings differ significantly, you may want to adjust your estimates accordingly. For large picture windows or sliding doors, consider adding extra deductions manually by reducing a wall dimension.

When ordering materials, always round up to the nearest whole sheet and consider buying one or two extra sheets for mistakes. Joint compound (mud) is estimated at about 0.053 gallons per square foot of drywall, and joint tape at one roll per 375 square feet. You will also need drywall screws (roughly 32 screws per 4x8 sheet), corner bead for outside corners, and appropriate tools.