Drywall Calculator – Sheets, Screws, Joint Compound & Cost Estimate
Calculate how many drywall sheets you need based on wall dimensions and room count. Includes waste allowance, screws, joint compound, and cost estimates for standard sheet sizes.
Drywall Calculator Formula
Sheets = Ceiling((Wall Area x Rooms x 1.10) / Sheet Area); Cost = Sheets x Price/Sheet
How to Calculate Drywall
- 1. Calculate total wall area: Total Area = Wall Length x Wall Height x Number of Rooms
- 2. Add 10% waste factor: Area with Waste = Total Area x 1.10
- 3. Determine sheet area: 4x8=32 sq ft, 4x10=40 sq ft, 4x12=48 sq ft
- 4. Calculate sheets needed: Sheets = Ceiling(Area with Waste / Sheet Area)
- 5. Estimate screws at ~1 per sq ft and joint compound at ~0.05 gal/sq ft
Example Calculation
Let's say you're drywalling a room with 48 ft perimeter, 8 ft ceilings using 4x8 sheets.
- wallLength: 48
- wallHeight: 8
- numRooms: 1
- sheetSize: 4x8
Total area: 384 sq ft, 14 sheets of 4x8 drywall, estimated cost: $168.00
Tips
- Always add at least 10% waste to your drywall order for cuts, mistakes, and offcuts around openings
- 4x8 sheets are the most common and easiest to handle — use 4x10 or 4x12 for rooms with 9-10 ft ceilings
- Standard 1/2-inch drywall works for most walls; use 5/8-inch for ceilings and fire-rated walls
- Hang drywall horizontally on walls for fewer seams and better structural strength
Frequently Asked Questions
How many sheets of drywall do I need for a 12x12 room?
A 12x12 room with 8-foot ceilings has a 48-foot perimeter and 384 sq ft of wall area. With 10% waste, you need about 422 sq ft of drywall, which equals 14 sheets of 4x8 drywall.
What size drywall sheets should I use?
4x8 foot sheets are the standard and easiest to transport and handle. Use 4x10 or 4x12 sheets for rooms with 9 or 10-foot ceilings to reduce the number of seams. Larger sheets mean fewer joints to tape and finish.
How much does drywall cost per sheet?
Standard 1/2-inch drywall costs approximately $12 per 4x8 sheet, $15 per 4x10 sheet, and $18 per 4x12 sheet. Prices vary by region and may include delivery fees for large orders.
How much joint compound do I need?
Plan for approximately 0.05 gallons of joint compound per square foot of drywall. For a 12x12 room with 384 sq ft of wall, that is about 19 gallons. A 5-gallon bucket of all-purpose compound covers roughly 100 sq ft.