Drywall Calculator
Sheet count for walls and ceiling, plus joint compound, tape and screws — with door/window deductions and 10% waste built in.
Quick presets — click to load typical room values:
Mud and tape figures use industry-standard rates (~0.053 gal compound and ~5 ft tape per sheet); actual usage varies with finish level. For estimating only.
Live wall + ceiling layout
Updates as you change inputs. Wall elevation on left with door/window openings. Ceiling top-down on right.
Yellow tiles = drywall sheets (staggered) · Brown = door · Light blue = window · Gray dashed = stud lines @ 16″ OC
📐 Fraction → decimal helper (tape measure conversions)
Type the decimal value into any input above. Example: 8-1/2 ft ceiling = 8.5 ; 12-1/4 ft length = 12.25.
Anatomy of a Finished Wall
What's actually between the studs and the paint. Cross-section through a typical interior wall, showing every layer.
Best Practices — Thickness, Screw Pattern, Orientation, Waste
Four reference scales for the drywalling decisions you actually make on every project.
Drywall Types — Which to Use Where
Five drywall variants. Standard 1/2″ is the default; the others solve specific problems.
Installation Details — Joints, Corners, Screws
Three details that decide whether the wall looks pro or like a DIY weekend.
How the Drywall Calculator Works
This drywall calculator estimates the number of sheets needed for a room by computing the total net wall area. It multiplies the room perimeter (2 × (length + width)) by the ceiling height to get gross wall area, then subtracts 21 sq ft per standard door (3×7 ft opening) and 15 sq ft per average window (3×5 ft). If you check "Include Ceiling," it adds the floor area (length × width). Total net area is divided by the sheet size — 32 sq ft for standard 4×8 panels, 48 sq ft for 4×12 — then a 10% waste factor is applied to cover cuts around corners, outlets and seams. Drywall is sold by the sheet and cannot be returned in partial quantities, so always round up to the nearest whole sheet.
Drywall Thickness Guide — Which to Use Where
| Thickness | Weight (lb/sheet) | Best Use | Notes |
|---|---|---|---|
| 1/4 in | ~13 lb | Curved walls, overlay on existing drywall | Not a structural layer |
| 3/8 in | ~20 lb | Repair patches, single-layer re-drywalling | Less common today |
| 1/2 in | ~54 lb | Interior walls and ceilings (standard) | Most common residential choice |
| 5/8 in Type X | ~70 lb | Garages, fire-rated assemblies, ceilings | Required by code in many garage-to-living applications |
| 1/2 in moisture-resistant | ~55 lb | Bathrooms, laundry rooms (non-wet areas) | Green board — not for direct water contact |
| 1/2 in cement board | ~65 lb | Tile backer in wet areas (showers, tub surrounds) | Not drywall — cement-based backer board |
Quick Reference — Sheets Needed by Room Size
| Room Size | Ceiling Height | 4×8 Sheets (walls + ceiling) | Notes |
|---|---|---|---|
| 10×10 (bedroom) | 8 ft | ~14–16 | 1 door, 1 window |
| 12×12 (bedroom) | 8 ft | ~16–18 | 1 door, 2 windows |
| 12×16 (living room) | 8 ft | ~20–22 | 1 door, 2 windows |
| 20×20 (garage) | 9 ft | ~38–42 | 1 large garage door, 1 door |
| 24×24 (basement) | 8 ft | ~52–58 | 2 doors, 4 small windows |
Pro tips: Order walls and ceiling drywall separately so you can use 5/8-inch Type X on ceilings (better sag resistance on long spans) and standard 1/2-inch on walls. Buy 5–10% extra for mistakes — most big-box stores won't take back cut sheets. Use 4×12 sheets on 9-foot walls to eliminate the horizontal seam mid-wall.