Enter the room size. The calculator works out how many sheets of drywall to buy, plus screws, tape and joint compound, and compares the DIY cost with hiring a pro.
How the drywall calculator works
Sheets = area × (1 + waste %) ÷ sheet size, rounded up
Rules of thumb for the extras: about one screw per square foot, roughly 370 feet of joint tape per 1,000 sq ft, and about one gallon of joint compound per 100 sq ft for three coats.
Worked example: a 12 × 12 ft room with ceiling
The walls are 384 sq ft. Take out one door and two windows (51 sq ft) and add the 144 sq ft ceiling: 477 sq ft. With 10% waste you need 17 sheets of 4 × 8 drywall, about $238 of board. A professional hang-and-finish at $2.50 per sq ft would be about $1,190.
Drywall prices in 2026
| Item | Typical 2026 price |
|---|---|
| Standard ½-in sheet, 4 × 8 | $11–$20 |
| Moisture-resistant (green) board | $13–$19 per sheet |
| Fire-resistant ⅝-in board | $15–$25 per sheet |
| Professional install and finish | $1.50–$3.50 per sq ft |
HomeGnome reports a typical installed price of $2.80–$3.40 per sq ft, with labor alone at about $1.05–$2.70. Coastal cities run higher.
Frequently asked questions
Should I use 4 × 8 or 4 × 12 sheets?
4 × 12 sheets mean fewer seams to tape and look better on long walls, but they’re heavy and awkward. For DIY and small rooms, 4 × 8 is easier.
Which way should drywall run?
On walls, hang sheets horizontally. It reduces seams and puts the tapered joint at a comfortable working height.
What thickness do I need?
½ inch for most walls and ceilings, ⅝ inch fire-rated where code requires it, such as garage walls shared with the house.
Sources: HomeGnome drywall installation cost guide (2026); HomeServe drywall cost guide (March 2026); Inch Calculator (2026).
