Drywall Calculator
Free estimator for sheets, cost, mud, screws & tape — instant results for any room
Sheets
Cost
Mud
Screws
Tape
ft
ft
ft
sq ft
4'×8' (32 sq ft)
4'×10' (40 sq ft)
4'×12' (48 sq ft)
sq ft
DIY (materials only)
Professional install
Level 0–2 (basic)
Level 3 (standard)
Level 4 (smooth)
Level 5 (premium)
sq ft
All-Purpose
Topping
Setting
sq ft
16" on center
24" on center
sq ft
How to Calculate Drywall
Measure your walls and ceilings, then divide by the sheet size. Always add a waste factor for cuts and mistakes. The standard formula used by contractors is:
Sheets = (Wall Area + Ceiling Area − Openings) × (1 + Waste%) ÷ Sheet Size
For a standard 12×10 ft room with 8 ft ceilings, wall area = 352 sq ft, ceiling = 120 sq ft. After subtracting a door (21 sq ft) and window (15 sq ft), net area = 436 sq ft. With 10% waste and 4×8 sheets: ⌈436 × 1.1 ÷ 32⌉ = 15 sheets.
Drywall Sheet Sizes
| Size | Sq Ft | Weight | Best For |
|---|---|---|---|
| 4×8 ft | 32 | ~57 lbs | Most rooms, easy to handle |
| 4×10 ft | 40 | ~71 lbs | Fewer seams, taller walls |
| 4×12 ft | 48 | ~85 lbs | Large open areas, fewer joints |
How to Use This Calculator
Sheets Tab: Calculating Drywall Quantity
- Measure your room dimensions — length, width, and ceiling height in feet.
- Check the boxes for walls and/or ceiling coverage you need.
- Enter openings — number of standard doors (21 sq ft each) and windows (15 sq ft each).
- Choose sheet size — 4×8 is most common; 4×12 means fewer seams.
- Set waste factor — 10% for simple rooms, 15% for rooms with lots of angles.
Cost Tab: Estimating Project Expenses
- Select project type — DIY (materials only) or professional installation.
- Choose finish level — Level 3 is standard for most homes; Level 5 for painted walls requiring a flawless surface.
Mud Tab: Joint Compound Quantities
- All-Purpose compound covers approximately 20 gallons per 400 sq ft per coat.
- Topping compound covers more per gallon — lighter final coats.
- Setting compound (hot mud) dries chemically — faster but less workable.
Screw Tab: Fastener Quantities
- 16" OC studs: ~32 screws per 4×8 sheet
- 24" OC studs: ~24 screws per 4×8 sheet
- Always buy 1-5/8" coarse thread drywall screws for wood studs.
Real-World Examples
Example 1: Standard Bedroom (12×10 ft, 8 ft ceiling)
- Wall area: 2×(12+10)×8 = 352 sq ft
- Ceiling: 12×10 = 120 sq ft
- Less: 1 door (21) + 1 window (15) = 36 sq ft
- Net: 436 sq ft → 15 sheets (4×8, 10% waste)
- DIY material cost: ~$186–$283
Example 2: Open-Plan Living Area (20×16 ft, 9 ft ceiling)
- Wall area: 2×(20+16)×9 = 648 sq ft
- Ceiling: 20×16 = 320 sq ft
- Less: 2 doors + 3 windows = 87 sq ft
- Net: 881 sq ft → 30 sheets (4×8, 10% waste)
Example 3: Small Bathroom (5×7 ft, 8 ft ceiling)
- Use moisture-resistant (green board) or cement board for wet areas
- Net area: ~140 sq ft → 5 sheets
Common Mistakes to Avoid
- Not adding waste — always add at least 10%; 15% for complex rooms
- Forgetting the ceiling — ceiling often adds 25–35% more material
- Wrong thickness — use 5/8" for fire-rated walls and garage ceilings
- Underestimating mud — plan for 3 coats minimum for a proper finish
When to Use This Calculator
- New construction framing ready for drywall
- Room remodel or renovation
- Basement finishing projects
- Garage conversion
- Home addition or room addition
Quick Reference Tables
Drywall Coverage by Sheet Size
| Sheets | 4×8 (sq ft) | 4×10 (sq ft) | 4×12 (sq ft) |
|---|---|---|---|
| 5 | 160 | 200 | 240 |
| 10 | 320 | 400 | 480 |
| 15 | 480 | 600 | 720 |
| 20 | 640 | 800 | 960 |
| 30 | 960 | 1,200 | 1,440 |
Frequently Asked Questions
How many sheets of drywall do I need for a 12×12 room? ▾
For a 12×12 room with 8 ft ceilings: wall area = 4×12×8 = 384 sq ft, ceiling = 144 sq ft. Total ~528 sq ft. Subtract 1 door and 1 window (36 sq ft) = 492 sq ft. With 10% waste ÷ 32 = about 17 sheets of 4×8 drywall.
How much does it cost to drywall a room? ▾
DIY material cost runs $0.45–$0.75 per sq ft for basic finish. Professional installation (labor + materials) costs $1.50–$3.50 per sq ft depending on your region and finish level. A standard 12×12 bedroom typically costs $300–$900 professionally installed.
How much joint compound (mud) do I need? ▾
A general rule: plan for 0.053 gallons of all-purpose compound per sq ft per coat. For 3 coats on 400 sq ft, that's about 64 gallons — roughly 13 five-gallon buckets. Always buy a little extra; unused compound keeps well sealed.
What thickness of drywall should I use? ▾
1/2" (12.7mm) is standard for most interior walls and ceilings. Use 5/8" (15.9mm) for fire-rated assemblies, garage ceilings, and anywhere the code requires Type X drywall. Use 3/8" only for curved surfaces or double-layer applications.
Should I hang drywall horizontally or vertically? ▾
Horizontal hanging is preferred for most walls — it creates fewer seams at eye level, provides better support, and produces a stronger wall. Vertical hanging is easier for beginners and works well for 8 ft ceilings when sheets fit wall-to-wall without cutting.