Drywall Calculator
Estimate drywall sheets, joint compound, tape, and screws for any room
Enter Room Dimensions
Quick Answer
A standard 4×8 drywall sheet covers 32 square feet. For a typical 12×10 room with 8-foot ceilings, you need approximately 14-15 sheets including waste factor.
Planning a drywall installation? This calculator determines exactly how many sheets you need plus all finishing materials: joint compound (mud), tape, and screws. Account for doors, windows, and waste to avoid multiple trips to the store.
Dr. Snezana Lawrence
Mathematical Historian
15+ years experience
PhD from Yale University. Published mathematical historian ensuring precision in all calculations.
Education
PhD in Mathematical History - Yale University
How to Calculate Drywall Needs
Formula: (Wall Area - Openings) ÷ Sheet Size × Waste Factor = Sheets
- Step 1: Calculate wall area: Perimeter = (Length + Width) × 2, Wall Area = Perimeter × Height
- Step 2: Subtract openings: Doors (~21 sq ft each), Windows (~15 sq ft each)
- Step 3: Add ceiling area if needed: Ceiling = Length × Width
Example: 12×10 room, 8 ft ceiling, 1 door, 2 windows
- • Wall area: (12+10)×2 × 8 = 352 sq ft
- • Minus openings: 352 - 21 - 30 = 301 sq ft
- • Ceiling: 12 × 10 = 120 sq ft
- • Total: 421 sq ft
- • Sheets (4×8): 421 ÷ 32 = 13.2 + 10% = 14.5 → 15 sheets
Drywall Sheet Sizes & Coverage
| Size | Coverage | Best For |
|---|---|---|
| 4×8 | 32 sq ft | 8 ft ceilings, most common |
| 4×10 | 40 sq ft | 9-10 ft ceilings |
| 4×12 | 48 sq ft | Commercial, tall walls |
| 4×9 | 36 sq ft | 9 ft ceilings |
Drywall Thickness Guide
| Thickness | Applications | Price |
|---|---|---|
| 1/4" | Overlay, curved walls | $8-12/sheet |
| 3/8" | Repair, double layer | $10-14/sheet |
| 1/2" | Standard walls/ceilings | $12-18/sheet |
| 5/8" | Fire-rated, soundproof | $15-22/sheet |
Drywall Supplies Coverage Chart
| Material | Coverage | For 500 sq ft |
|---|---|---|
| Joint Compound | 1 gal per 100 sq ft | 5 gallons |
| Drywall Tape | 1 roll (250') per 500 sq ft | 1 roll |
| Screws | 1 lb per 5 sheets | 2-3 lbs |
| Corner Bead | 1 per corner | 4-8 pieces |
Drywall Installation Pro Tips
- • Hang ceiling sheets first, then walls
- • Stagger seams for strength (don't align)
- • Use 4×12 sheets vertically to reduce seams
- • Cut holes for outlets before hanging
- • Screw every 12" on studs, 7" on ceilings
- • Keep screws 3/8" from edges
- • Apply 3 coats of mud, sanding between
- • Use mesh tape for cracks, paper for flat seams
Frequently Asked Questions
How many sheets of drywall do I need for a 12×12 room?
Walls: (12+12)×2 × 8 = 384 sq ft ÷ 32 = 12 sheets. Ceiling: 12×12 = 144 sq ft ÷ 32 = 4.5 sheets. Total: 17 sheets (with waste).
Should I subtract door and window openings?
Yes, subtract doors (~21 sq ft) and windows (~15 sq ft). This prevents overordering, though some contractors don't subtract to have extra.
How much joint compound do I need?
Plan for 1 gallon per 100 sq ft of drywall. A 500 sq ft room needs 5 gallons (one 5-gallon bucket).
How many screws per sheet of drywall?
Approximately 32-36 screws per 4×8 sheet (every 12" on studs). 1 pound of screws covers about 5 sheets.
What size drywall for 9-foot ceilings?
Use 4×9 or 4×10 sheets for 9-foot ceilings. Reduces seams compared to using 4×8 sheets horizontally.
Do I need different thickness for walls vs ceilings?
Walls: 1/2" standard. Ceilings: 5/8" recommended (less sag, better soundproof). Fire-rated areas require 5/8" Type X.
How much waste factor should I add?
Add 10% for simple rooms, 15% for complex layouts, 20% for rooms with many angles or if you're inexperienced.
Can one person hang drywall alone?
Walls yes, ceilings no. Ceiling sheets are heavy (50-75 lbs) and require 2 people or a drywall lift for safe installation.
Dr. Snezana Lawrence
Mathematical Historian | PhD from Yale
Dr. Lawrence is a published mathematical historian with a PhD from Yale University. She ensures mathematical precision and accuracy in all our calculations, conversions, and academic score calculators. Her expertise spans computational mathematics and educational assessment.
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