Drywall Calculator
Estimate drywall sheets, screws, tape and joint compound for walls and ceilings.
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How to Calculate
Area = total wall length × height, plus ceiling area. Divide by sheet area and add 10% waste.
Plan about one screw per square foot of drywall (roughly 32 per 4×8 sheet).
Rule of thumb: about 4.5 gallons of joint compound and 185 ft of tape per 500 ft² of drywall.
See our methodology for how every calculator on this site is built.
Worked Example: A 12 × 14 Room with Ceiling
Walls are 8 ft tall. You're hanging both the walls and the ceiling, with 10% waste.
- Perimeter: 12 + 14 + 12 + 14 = 52 ft
- Wall area: 52 × 8 = 416 ft²
- Ceiling: 12 × 14 = 168 ft²
- Total: 584 ft²
- With waste: 584 × 1.10 = 642.4 ft²
- 4 × 8 sheets: 642.4 ÷ 32 = 20.1, so 21 sheets
- 4 × 12 sheets: 642.4 ÷ 48 = 13.4, so 14 sheets
- Screws: about 21 × 32 = 672
- Joint compound: 584 ÷ 500 × 4.5 = 5.3, so about 6 gallons
- Tape: 584 × 0.37 = 216 ft
The 4 × 12 sheets mean fewer butt joints, which are the hardest joints to finish flat. On this ceiling, two 12 ft sheets run across the 12 ft width with no butt joints at all. They're heavy, though: a 1/2 inch 4 × 12 sheet weighs somewhere around 70 to 80 lb, and lifting them overhead without a drywall lift is a two-person job at minimum.
Sheets per 500 Square Feet
| Sheet size | Area per sheet | Sheets for 500 ft² (+10%) | Best for |
|---|---|---|---|
| 4 × 8 ft | 32 ft² | 18 | Small rooms, DIY, tight stairwells |
| 4 × 10 ft | 40 ft² | 14 | Walls with 9 or 10 ft ceilings |
| 4 × 12 ft | 48 ft² | 12 | Long walls and ceilings, fewer seams |
Hanging Tips
Ceiling first, then walls
Hang the ceiling first so the wall sheets hold up its edges. On walls, hang the top row first, tight to the ceiling, and leave any gap at the floor where baseboard will cover it.
Run sheets horizontally
On walls up to about 9 ft, hanging sheets horizontally puts the factory tapered edges at a comfortable height for taping and gives fewer linear feet of seams. It also bridges small differences between studs better.
Stagger the butt joints
Never line up end joints in a column. Stagger them by at least one stud bay, and try to keep butt joints away from the center of the wall where light will show them.
Screw depth matters
Screws should dimple the paper slightly without tearing it. A screw that breaks the paper face holds almost nothing. A dimpler bit for a regular drill is cheap and solves this. Use 1-1/4 inch coarse-thread screws for 1/2 inch board on wood studs.
Common Mistakes
- Hanging joints at the edge of a door or window opening. Cut the sheet to wrap around the corner of the opening so seams land at least a few inches away; corner seams crack.
- Forgetting blocking. Add backing for cabinets, grab bars, TV mounts and shelving before the drywall goes up.
- Using all-purpose mud for every coat. Many finishers use a setting-type compound for the tape coat for strength, then lightweight topping for the finish coats because it sands easier.
- Skipping the primer. Raw compound and paper absorb paint differently, so the seams show through. Use a drywall primer before painting.
Rough Cost
A standard 1/2 inch 4 × 8 sheet typically costs roughly $12 to $20, with moisture-resistant and 5/8 inch fire-rated boards costing more. A 4.5 gallon bucket of joint compound is usually $15 to $25. Professional hanging and finishing often adds $1.50 to $3.50 per ft² of board.
Sources
Common questions
Frequently Asked Questions
What size drywall should I buy?
4×8 sheets are easiest to handle; 4×12 sheets mean fewer seams on long walls and ceilings.
Do I subtract doors and windows?
Many pros don't — the cut-outs cover waste. Subtract only very large openings.
Which thickness?
1/2 in for walls, 5/8 in for ceilings and fire-rated assemblies.
What drywall goes in a bathroom?
Moisture-resistant (green or purple) board for bathroom walls and ceilings. Behind tile in a shower, use cement board or a foam board system instead.
How many coats of joint compound do I need?
Three: a tape coat, a fill coat and a final skim, each feathered wider than the last. Sand lightly between coats.