Drywall Calculator

How to Calculate Drywall

Measure your walls and ceilings, then divide by the sheet size. The Gypsum Association recommends calculating each surface area separately for the most accurate estimates. Basic formula:

Sheets = (Wall Area + Ceiling Area - Openings) × (1 + Waste%) ÷ Sheet Size

For a 12'×10' room with 8' ceilings: Walls = 352 sq ft, Ceiling = 120 sq ft. Minus 2 doors and 1 window (~57 sq ft) = 415 sq ft. Add 10% waste = 457 sq ft. Divide by 32 sq ft per sheet = 15 sheets.

Drywall Sheet Sizes

Sheet specifications per ASTM C1396 standard for gypsum board products.

How to Use This Calculator

This calculator includes five specialized tabs for estimating different drywall materials. Here's how to use each one effectively.

Sheets Tab: Calculating Drywall Quantity

1. Measure your room dimensions. Use a tape measure to get the length, width, and ceiling height in feet. Measure at floor level for length and width, and from floor to ceiling for height.
2. Enter the dimensions. Input your room length, width, and ceiling height into the corresponding fields.
3. Select coverage areas. Check "Walls" if you're drywalling the walls, "Ceiling" if you're covering the ceiling, or both. Uncheck areas you're not covering.
4. Count your openings. Enter the number of standard doors (calculated at 21 sq ft each) and windows (15 sq ft each). For non-standard openings like pass-throughs or large closets, enter the total square footage in "Other."
5. Choose your sheet size. 4'×8' sheets are most common and easiest to handle alone. 4'×10' and 4'×12' sheets reduce seams but require two people to carry and install.
6. Set your waste factor. The default 10% works for typical rectangular rooms. Increase to 15-20% for rooms with many corners, angles, or cutouts. Decrease to 5-7% for simple, open spaces.
7. Click "Calculate Sheets Needed." Review your results, including the complete shopping list for all materials.

Cost Tab: Estimating Project Expenses

1. Enter square footage. Use the total from the Sheets tab, or enter your known square footage directly.
2. Select project type. Choose "DIY" for materials-only estimates, or "Professional install" to include labor costs.
3. Pick your finish level. Level 0-2 is basic (garage, utility rooms). Level 3 is standard (most residential). Level 4 is smooth (visible walls). Level 5 is premium (high-gloss paint, critical lighting).
4. Review the cost range. The calculator provides low and high estimates reflecting regional price variations. Verify current prices at Home Depot or Lowe's for your area.

Mud Tab: Joint Compound Quantities

1. Enter your square footage.
2. Select compound type. All-Purpose works for most applications. Topping is for final coats only. Setting compound dries faster but requires more skill.
3. Choose number of coats. Three coats is standard for a Level 4 finish. Use fewer for basic finishes, more for Level 5.
4. Check the bucket quantities. The calculator shows how many 5-gallon and 1-gallon containers to purchase.

Screws Tab: Fastener Quantities

1. Enter square footage.
2. Select stud spacing. Most residential construction uses 16" on-center per ICC building codes. Older homes or commercial buildings may use 24" on-center.
3. Note the box quantities. Screws are sold by weight; the calculator converts to 5-lb box quantities for easy purchasing.

Tape Tab: Paper Tape Requirements

1. Enter square footage.
2. Choose corner tape option. Check this to include tape for inside corners and ceiling edges. Uncheck for flat seams only.
3. Review roll quantities. Paper tape comes in 75-ft, 250-ft, and 500-ft rolls.

Tips for Accurate Results

• Measure twice. Double-check all dimensions before entering them.
• Round up slightly. If a room is 11'8", enter 12' to ensure adequate materials.
• Don't forget closets. Include closet interiors if you're drywalling them.
• Consider ceiling height. Standard is 8', but many homes have 9' or 10' ceilings.
• Account for complexity. Increase waste factor for bathrooms, kitchens, or rooms with many electrical boxes.

Common Mistakes to Avoid

• Forgetting the ceiling. Many first-time estimators calculate only walls.
• Underestimating waste. Cuts around outlets, windows, and corners generate significant scrap.
• Ignoring sheet size limits. Larger sheets are more efficient but may not fit through doorways or up stairs.
• Calculating rooms separately. If drywalling multiple rooms, calculate each one and add totals—don't average.
• Buying exact quantities. Always round up to the nearest full unit and buy 1-2 extra sheets for mistakes.

Real-World Examples

See how different projects use the calculator with actual numbers based on the formulas.

Example 1: Standard Bedroom Renovation

Scenario: Maria is renovating a 12' × 10' bedroom with 8' ceilings. The room has one standard door and two windows. She's doing the work herself and wants a standard Level 3 finish.

Inputs: Length: 12 ft, Width: 10 ft, Height: 8 ft, Walls and ceiling checked, 1 door, 2 windows, 4'×8' sheets, 10% waste.

Calculations:

• Wall perimeter: 2 × (12 + 10) = 44 ft
• Wall area: 44 × 8 = 352 sq ft
• Ceiling area: 12 × 10 = 120 sq ft
• Openings: 1 door (21 sq ft) + 2 windows (30 sq ft) = 51 sq ft
• Net area: 352 - 51 + 120 = 421 sq ft
• With 10% waste: 421 × 1.10 = 463 sq ft
• Sheets needed: 463 ÷ 32 = 15 sheets (rounded up)

Results: 15 sheets of 4'×8' drywall, approximately 6 gallons of joint compound, 126 ft of tape, and 421 screws. Estimated DIY materials cost: $188-$273.

Example 2: Basement Finishing Project

Scenario: James is finishing a 24' × 20' basement with 7.5' ceilings. The space has three small windows (12 sq ft each instead of standard), one door to the stairs, and one door to a bathroom. He plans to hire a professional for Level 4 finish quality.

Inputs: Length: 24 ft, Width: 20 ft, Height: 7.5 ft (enter 8), Walls and ceiling, 2 doors, 0 standard windows, 36 sq ft in "Other" for small windows, 4'×12' sheets for fewer seams, 12% waste (basement complexity).

Calculations:

• Wall perimeter: 2 × (24 + 20) = 88 ft
• Wall area: 88 × 8 = 704 sq ft
• Ceiling area: 24 × 20 = 480 sq ft
• Openings: 2 doors (42 sq ft) + 36 sq ft other = 78 sq ft
• Net area: 704 - 78 + 480 = 1,106 sq ft
• With 12% waste: 1,106 × 1.12 = 1,239 sq ft
• Sheets needed: 1,239 ÷ 48 = 26 sheets (4'×12')

Results: 26 sheets of 4'×12' drywall. Professional Level 4 installation: $2,212-$3,042 total including materials and labor.

Example 3: Small Bathroom Remodel

Scenario: David is replacing water-damaged drywall in a 6' × 8' bathroom with 8' ceilings. He's only doing the walls (ceiling is fine) and needs moisture-resistant drywall. One door, no windows.

Inputs: Length: 6 ft, Width: 8 ft, Height: 8 ft, Walls only (ceiling unchecked), 1 door, 0 windows, 4'×8' sheets, 15% waste (small room = more cuts).

Calculations:

• Wall perimeter: 2 × (6 + 8) = 28 ft
• Wall area: 28 × 8 = 224 sq ft
• Openings: 1 door = 21 sq ft
• Net area: 224 - 21 = 203 sq ft
• With 15% waste: 203 × 1.15 = 233 sq ft
• Sheets needed: 233 ÷ 32 = 8 sheets

Results: 8 sheets of 4'×8' moisture-resistant drywall. Note: Use green board or purple board rated for high-moisture areas.

Example 4: Open-Plan Living Area

Scenario: The Johnsons are building a new 28' × 18' great room with 10' ceilings. The space has a large sliding door (50 sq ft), two standard windows, and opens to the kitchen (no door). They're using 4'×12' sheets to minimize seams on the tall walls.

Inputs: Length: 28 ft, Width: 18 ft, Height: 10 ft, Walls and ceiling, 0 doors, 2 windows, 50 sq ft in "Other" for slider, 4'×12' sheets, 10% waste.

Calculations:

• Wall perimeter: 2 × (28 + 18) = 92 ft
• Wall area: 92 × 10 = 920 sq ft
• Ceiling area: 28 × 18 = 504 sq ft
• Openings: 2 windows (30 sq ft) + 50 sq ft slider = 80 sq ft
• Net area: 920 - 80 + 504 = 1,344 sq ft
• With 10% waste: 1,344 × 1.10 = 1,478 sq ft
• Sheets needed: 1,478 ÷ 48 = 31 sheets

Results: 31 sheets of 4'×12' drywall, 20 gallons of compound, 403 ft of tape, 1,344 screws.

Example 5: Garage Conversion

Scenario: Alex is converting a 20' × 22' two-car garage into a home office. The space has 9' ceilings, one large garage door opening being walled in (150 sq ft), one entry door, and no windows (will add later). Using fire-rated 5/8" drywall per code.

Inputs: Length: 20 ft, Width: 22 ft, Height: 9 ft, Walls and ceiling, 1 door, 0 windows, 0 sq ft in "Other" (garage door is being covered, not subtracted), 4'×8' sheets, 10% waste.

Calculations:

• Wall perimeter: 2 × (20 + 22) = 84 ft
• Wall area: 84 × 9 = 756 sq ft
• Ceiling area: 20 × 22 = 440 sq ft
• Openings: 1 door = 21 sq ft
• Net area: 756 - 21 + 440 = 1,175 sq ft
• With 10% waste: 1,175 × 1.10 = 1,293 sq ft
• Sheets needed: 1,293 ÷ 32 = 41 sheets

Results: 41 sheets of 4'×8' Type X (fire-rated) drywall. Materials cost estimate: $472-$685 for DIY.

Example 6: Contractor Whole-House Estimate

Scenario: A contractor is bidding on a new construction home with 2,400 sq ft of drywall area (already calculated by the architect). Standard 8' ceilings throughout, Level 3 finish, professional installation.

Using Cost Tab: Enter 2,400 sq ft, select "Professional install," choose "Level 3 (standard)."

Results:

• Materials: $960-$1,392
• Labor (Level 3): $3,600-$5,400
• Total estimate: $4,560-$6,792
• Per square foot: $1.90-$2.83

The contractor can use this range as a starting point, then adjust based on local labor rates and material suppliers.

When to Use This Calculator

This drywall calculator is designed to help with material estimation in a variety of situations. Here's when it's most useful:

Ideal Use Cases

• DIY home renovation. Planning a bedroom, basement, or garage project? Get accurate material lists before your hardware store trip.
• Budgeting a project. Use the cost estimator to understand expense ranges before committing to work.
• Comparing DIY vs. professional costs. See the difference between materials-only and full installation pricing.
• Creating shopping lists. The Sheets tab generates a complete list including compound, tape, and screws.
• Verifying contractor bids. Check that quoted material quantities are reasonable for your space.
• Planning room additions. Estimate drywall needs when designing new living space.
• Water damage repair. Calculate materials needed to replace damaged sections.
• Finishing unfinished spaces. Basements, attics, and bonus rooms often need complete drywall installation.

Who Benefits Most

• First-time DIYers who need guidance on quantities and materials.
• Homeowners planning renovations and setting budgets.
• Contractors preparing quick estimates for client quotes.
• Property managers budgeting for rental property repairs.
• Real estate investors estimating renovation costs for potential purchases.

Important Considerations

While this calculator provides reliable estimates, remember that:

• Complex room shapes may require additional materials beyond the estimate.
• Local material and labor costs vary significantly by region.
• Fire-rated, moisture-resistant, and specialty drywall cost more than standard.
• Professional installation includes prep work, delivery, and cleanup not reflected in materials-only estimates.
• Always consult local building codes for thickness and type requirements.

Quick Reference Tables

Use these reference tables for quick estimates and to verify your calculator results.

Drywall Coverage by Sheet Size

Joint Compound Coverage Rates

Screw Requirements by Stud Spacing

Note: A 5-lb box contains approximately 660 screws (1-5/8" coarse thread).

Paper Tape Requirements

Formula Reference

Understand the math behind the calculator with these formulas and worked examples.

Wall Area Calculation

Formula: Wall Area = 2 × (Length + Width) × Height

Example: Room is 12' × 10' with 8' ceilings

• Perimeter = 2 × (12 + 10) = 44 feet
• Wall area = 44 × 8 = 352 sq ft

Ceiling Area Calculation

Formula: Ceiling Area = Length × Width

Example: Room is 12' × 10'

• Ceiling area = 12 × 10 = 120 sq ft

Standard Opening Deductions

Total Sheets Formula

Formula: Sheets = ⌈(Total Area × Waste Factor) ÷ Sheet Size⌉

Example: 421 sq ft with 10% waste using 4'×8' sheets

• With waste = 421 × 1.10 = 463 sq ft
• Sheets = 463 ÷ 32 = 14.47
• Round up = 15 sheets

Joint Compound Formula

Formula: Gallons = (Square Footage × Coverage Rate) × Number of Coats

Coverage Rates:

• All-Purpose: 0.05 gallons per sq ft per coat (20 sq ft coverage per gallon)
• Topping: 0.03 gallons per sq ft per coat (33 sq ft coverage per gallon)
• Setting: 0.04 gallons per sq ft per coat (25 sq ft coverage per gallon)

Example: 400 sq ft with All-Purpose, 3 coats

• Per coat = 400 × 0.05 = 20 gallons total
• Total = 20 ÷ 3 coats displayed as ~6.7 gallons per coat
• Purchase: 4× 5-gallon buckets (20 gallons)

Screw Calculation Formula

Formula: Screws = Square Footage × Screws Per Sq Ft

Rates: 16" OC = 1.0 screw/sq ft | 24" OC = 0.75 screws/sq ft

Example: 400 sq ft with 16" on-center studs

• Screws = 400 × 1.0 = 400 screws
• Weight: 400 ÷ 660 × 5 = 3.0 lbs
• Purchase: 1× 5-lb box

Tape Calculation Formula

Formula: Tape (linear ft) = Square Footage × 0.3

Example: 400 sq ft (flat seams only)

• Tape = 400 × 0.3 = 120 linear feet
• 75-ft rolls needed = 120 ÷ 75 = 2 rolls

Understanding Your Results

Here's how to interpret the calculator output and make purchasing decisions.

Reading the Sheets Calculator Results

• Total Sheets Needed: The primary result—how many full sheets to buy. This number is already rounded up.
• Wall Area / Ceiling Area: Breakdown showing square footage for each surface before deductions.
• Total with Waste: The final square footage used for calculations, including your selected waste percentage.
• Shopping List: A complete materials list based on your project size, including estimated compound, tape, and screws.

Cost Estimate Interpretation

• Materials Range: The low-to-high estimate for drywall, compound, tape, and fasteners. Actual prices depend on your location and supplier.
• Labor Range: Professional installation costs, which vary by region and finish level. Urban areas typically cost more than rural.
• Per Square Foot Cost: Useful for comparing to contractor quotes. If a bid is significantly higher or lower, ask why.

Waste Factor Guidelines

When to Buy Extra

• First-time installers: Add 1-2 extra sheets beyond the calculated amount for learning mistakes.
• Unknown wall conditions: Older homes may reveal surprises requiring additional materials.
• Future repairs: Having matching material stored makes patching easier later.
• Transportation damage: Some sheets may arrive damaged or break during handling.

Drywall Type Comparison

Choose the right drywall type for your project based on location and requirements.

Product data compiled from USG, CertainTeed, and other major manufacturers.

Thickness Selection Guide

Finish Level Comparison

Finish levels defined by Gypsum Association standard GA-214.

Related Guides

Explore our in-depth articles for more detailed information on drywall projects.

View all articles →

Frequently Asked Questions