# Drywall Calculator: How Many Sheets Do I Need?

> Find the number of drywall sheets, screws, tape and joint compound for a room, including doors, windows and waste.

**Quick answer:** A 12 × 12 ft room with 8-ft walls and a ceiling needs about 17 sheets of 4×8 drywall: roughly 477 sq ft of surface after one door and two windows, plus 10% waste, at 32 sq ft per sheet. Formula: area × 1.10 ÷ 32 = sheets.

_Last updated: October 3, 2026. Estimates only; confirm quantities with your supplier._

## How to calculate drywall sheets

Add up the wall (and ceiling) area, subtract large openings, add waste, and divide by the area of one sheet.

```
area = 2 × (length + width) × height + (ceiling: length × width) − openings
sheets = area × (1 + waste %) ÷ sheet area
```

A standard 4 × 8 foot sheet covers 32 square feet. Larger 4 × 12 sheets cover 48 square feet and create fewer seams on long walls, which means less taping and a smoother finish — but they are heavy and hard to maneuver alone.

### Drywall sheets by room size (walls + ceiling, 10% waste, 4×8 sheets)

| Room size (8 ft walls) | Walls + ceiling (sq ft) | Sheets |
| --- | --- | --- |
| 10 × 10 ft | 369 | 13 |
| 10 × 12 ft | 421 | 15 |
| 12 × 12 ft | 477 | 17 |
| 12 × 14 ft | 533 | 19 |
| 12 × 16 ft | 589 | 21 |
| 14 × 16 ft | 653 | 23 |
| 16 × 20 ft | 845 | 30 |

The chart assumes one door and two windows; adjust the inputs for your room.

### Waste and cuts

Plan on 10% waste for a simple rectangular room and 15% for rooms with many corners, angles or small walls. Offcuts are often too small to reuse.

### Screws, tape and compound

A common rule of thumb is about 32 screws per 4×8 sheet (one every 12 inches along studs), roughly 0.37 feet of paper or mesh tape per square foot, and about a gallon of joint compound for every 100 square feet across all coats. These are estimates — heavy finishing, skim coats and textured walls use more.

### Choosing thickness

| Use | Typical thickness |
| --- | --- |
| Standard walls | 1/2 in |
| Ceilings (16 in. joist spacing) | 1/2 in sag-resistant or 5/8 in |
| Fire-rated assemblies, garages | 5/8 in Type X |
| Curved walls | 1/4 in flexible |
| Bathrooms and wet areas | Moisture-resistant (green/purple board) |

After hanging, the walls are ready for the [paint calculator](../paint-calculator/) or [wallpaper calculator](../wallpaper-calculator/). Insulate first with the [insulation calculator](../insulation-calculator/).

## Frequently asked questions

### How many sheets of drywall do I need for a 12×12 room?

A 12×12 room with 8-foot walls and a ceiling needs about 17 sheets of 4×8 drywall, including 10% waste, one door and two windows.

### How many square feet is a sheet of drywall?

A 4×8 sheet covers 32 sq ft; a 4×10 sheet covers 40 sq ft; a 4×12 sheet covers 48 sq ft.

### Should I hang drywall horizontally or vertically?

Horizontal (perpendicular to studs) is generally preferred on 8-foot walls: it reduces seams and adds stiffness. On ceilings, run sheets perpendicular to the joists.

### How many screws per sheet of drywall?

Roughly 28–40 per 4×8 sheet; 32 is a common estimate, using screws every 12 inches on the ceiling and 16 inches on walls.

### How much joint compound do I need?

About 1 gallon per 100 sq ft of drywall for taping and two to three finishing coats. A 4.5-gallon bucket covers roughly 450 sq ft.

### How much does a sheet of drywall cost?

A 1/2 in 4×8 sheet commonly costs about $12–$20, with 5/8 in and specialty boards costing more.

### Do I need to subtract windows and doors?

Yes for a tight estimate, but small openings can be left in as extra waste allowance.

### How many sheets do I need for a ceiling?

Divide the ceiling area by 32 for 4×8 sheets and add 10%. A 12×12 ceiling needs 5 sheets.