A standard door is about 21 ft², a window about 16 ft².
For 9–10 ft walls, 4x12 hung horizontally reduces butt joints.
How to Calculate Drywall for Any Room
The core calculation is straightforward: work out the total wall area (perimeter times wall height), add the ceiling area if you're drywalling it, subtract the area of doors and windows, then divide by the area of a single sheet. Round up to whole sheets, add your waste factor on top, and that's your order quantity. Everything else, screws, tape, compound, corner bead, flows from that base area figure.
Screws are estimated at roughly 1.2 per square foot on walls and 1.4 per square foot on ceilings, which accounts for the closer fastener spacing required overhead. Joint tape is approximated at about 0.7 linear feet per square foot of drywall area. Compound usage depends on your finish level: a Level 3 finish (the standard for painted walls) uses roughly one 4.5-gallon bucket per 400 square feet, while a Level 5 skim coat can use nearly twice that.
Choosing the Right Sheet Size
The 4x8 sheet is the standard and what most home centres stock in quantity. For rooms with 9 or 10 foot ceilings, the 4x12 sheet hung horizontally is a better choice. It spans the full wall height with one horizontal seam rather than two, which means less taping, less mudding, and a better-looking finished wall. The 4x10 sits between the two and works well for 9-foot ceilings when 4x12 boards are harder to transport.
Finish Levels and What They Mean
Drywall finish levels run from Level 1 (basic tape embedded, no finishing coat, used in spaces that won't be seen) to Level 5 (full skim coat over the entire surface, required for high-gloss paint or critical lighting conditions). Level 3 is the standard for most painted interior walls: tape embedded, two finish coats, lightly sanded. If you're planning to paint with flat or eggshell sheen, Level 3 is usually sufficient. For semi-gloss or gloss finishes, or walls that will catch strong raking light, consider Level 4 or 5.
Drywall Types by Application
| Type | Thickness | Best For |
|---|---|---|
| Standard | 1/2" | Most interior walls, 16" OC framing |
| Fire-rated (Type X) | 5/8" | Garages, furnace rooms, party walls |
| Moisture-resistant (green board) | 1/2" | Bathrooms, laundry rooms (not a tile backer) |
| Ceiling (sag-resistant) | 5/8" | Ceilings, especially with insulation above |
Rough Material Costs
These are approximate US retail prices as of 2025. Contractor pricing and volume discounts will be lower.
| Material | Unit | Approx. Cost | Notes |
|---|---|---|---|
| 1/2" standard drywall | per 4x8 sheet | $12 – $18 | Most common; price varies by region |
| 5/8" fire-rated (Type X) | per 4x8 sheet | $16 – $24 | Required in garages and many fire-rated assemblies |
| Drywall screws (1 lb box) | ~200 screws | $5 – $9 | Buy by the 5 lb box for larger jobs |
| Paper joint tape | 250 ft roll | $5 – $8 | Mesh tape also available; paper is stronger for flat seams |
| All-purpose joint compound | 4.5 gal bucket | $18 – $28 | Covers approx 400 ft² at Level 3 finish |
| Corner bead (metal) | 8 ft stick | $2 – $4 | Vinyl bead also available for impact resistance |
Labour for drywall installation typically runs $1.50 to $3.50 per square foot installed, including hanging, taping, and finishing to Level 3.
Frequently Asked Questions
Drywall Project Planning Checklist
Before ordering, confirm framing is plumb and square, moisture levels are acceptable, and you have the right board type for each area of the room.
Download Checklist (PDF)Planning use only. See Methodology and Data Sources. View all project checklists →
Related Calculators
Disclaimer
Results are provided for general planning and budgeting purposes only. Actual quantities may vary based on room layout complexity, framing condition, installer technique, and product specifications.
Surface preparation, substrate irregularities, and finish level requirements may increase material quantities beyond these estimates.
See our Methodology and Data Sources for details.