Drywall Calculator

How many drywall sheets do I need? Add wall area — 2 × (length + width) × height — plus the ceiling (length × width) if you hang it, multiply by 1.10 for about 10% waste, then divide by sheet area (4×8 = 32, 4×10 = 40, 4×12 = 48 sq ft) and round up. A 12×12 room with 8 ft ceilings, ceiling included, needs 528 sq ft of surface — 19 sheets of 4×8.

Reviewed / updated August 2026

Full walkthrough: How to Estimate Materials for Any Home Project

Your inputs

ft
ft
ft

Adds length × width to the surface area before the 10% waste factor.

Result

Sheets to buy

19

528 sq ft surface · 4×8 sheets

Total surface
528 sq ft
With 10% waste
581 sq ft
Sheets (rounded up)
19

528 sq ft of walls and ceiling with a 10% waste buffer needs 19 sheets of 4×8 drywall (rounded up).

Ceiling on vs off

SurfacesSq ftSheets
Walls + ceiling52819
Walls only38414

Suggested next steps

  • Hang longer sheets on longer walls when you can — fewer seams often beat a slightly lower sheet count.
  • Ceiling sheets are heavier to lift — plan a helper or a drywall lift for safety.
  • Large jobs may justify a delivery fee — confirm sheet count against your cut list.

How the drywall calculation works

Hang counts start from the four walls, optionally add the ceiling, then apply a waste buffer before dividing by sheet area:

  1. Surface = 2 × (L + W) × H + (ceiling? L × W : 0)
  2. With waste = surface × 1.10
  3. Sheets = ceil(with waste ÷ sheet area)

| Sheet | Area | | --- | --- | | 4×8 | 32 sq ft | | 4×10 | 40 sq ft | | 4×12 | 48 sq ft |

This estimator does not subtract every door and window. The 10% waste factor usually covers openings and cutoffs for rectangular rooms. For a tighter takeoff, subtract large openings manually. Longer 4×10 or 4×12 sheets reduce seams on tall walls but are heavier—plan a helper or lift for ceilings.

Source note: The 10% waste factor is a common DIY planning buffer for cuts and breakage; it is not a substitute for a full cut list. Updated August 2026.

Worked example

Room 12 × 12 ft, height 8 ft, ceiling on, 4×8 sheets:

  1. Walls = 2 × 24 × 8 = 384 sq ft
  2. Ceiling = 144 sq ft
  3. Total = 528 sq ft
  4. With waste = 528 × 1.10 = 580.8
  5. Sheets = ceil(580.8 ÷ 32) = 19

Defaults match this example. Use the ceiling on/off table to compare walls-only counts before you buy. After hanging, move on to mud, tape, and paint with the matching calculators in this category.

Tips and related tools

Frequently asked questions

How many 4×8 sheets for a 12×12 room?

Walls = 2 × (12 + 12) × 8 = 384 sq ft. Ceiling = 144 sq ft. Total = 528 sq ft. With 10% waste ≈ 580.8 sq ft. Sheets = ceil(580.8 ÷ 32) = 19 of the 4×8 sheets.

Should I include the ceiling?

Only if you are hanging drywall on it. Toggle “Include ceiling” off for walls-only jobs. The comparison table shows both counts for your room size.

Why not subtract doors and windows?

This estimator uses a 10% waste buffer instead of opening deductions. That usually covers doors, windows, and cutoffs for rectangular rooms. For a tighter takeoff, subtract large openings manually and re-run.

Which sheet size should I buy?

4×8 is easiest to handle. 4×10 and 4×12 reduce seams on taller or longer walls but are heavier. Pick the size that fits your walls and crew.

Do I need moisture-resistant board?

Bathrooms and other damp areas often use mold-resistant or green board. Sheet count math is the same — choose the product rated for the room.

Related tools

Related calculators — live tools and upcoming pages for internal linking.