Drywall Calculator

Calculate drywall sheets needed, disposal weight, and material estimates for your project. Supports multiple sheet sizes and accounts for waste factors.

Drywall Material Calculator

Industry-standard calculations per ASTM C840 & USG specifications

feet
feet
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sq ft

Typical door: 20 sq ft | Standard window: 15 sq ft

Sheet Size

Wall Drywall Thickness

Frequently Asked Questions

What size drywall sheets should I use?

Standard 4×8 sheets (32 square feet) work for most walls. 4×12 sheets (48 square feet) reduce seams and are preferred for walls over 8 feet tall. Use 4×12 or 54-inch-wide sheets for ceilings to minimize butt joints. Longer sheets reduce finishing time but are harder to maneuver.

What thickness drywall do I need?

Standard walls use 1/2 inch drywall. Ceilings with 16-inch joist spacing use 1/2 inch; 24-inch spacing requires 5/8 inch per code. Fire-rated assemblies require 5/8 inch Type X. Moisture areas need 1/2 inch or 5/8 inch purple board or cement board.

How much joint compound do I need?

Plan for approximately 280 square feet of coverage per gallon per coat based on USG specifications. For a complete three-coat finish (tape coat, fill coat, finish coat), you'll need about 3 gallons per 280 square feet, or roughly 0.011 gallons per square foot total. A 1,000 square foot project requires approximately 11 gallons for all three coats.

Why calculate 10-15% waste for drywall?

Waste accounts for cuts around doors, windows, outlets, and corners. Simple rectangular rooms need 10% waste for walls. Ceilings require 14% waste (10% plus 4% for overhead installation difficulty). Complex layouts with angles, soffits, or many openings require 15% waste overall.

Industry Standards Referenced

Last verified: November 2025

Gypsum Association (GA) Standards(GA-216 Application Guidelines)

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Industry standards for gypsum board application including framing requirements, fastener specifications, joint treatment, and finishing levels. Primary reference for professional drywall installation.

Key Requirements:

  • •Maximum spacing: 16 inches on-center for 1/2-inch board, 24 inches for 5/8-inch
  • •Fastener spacing: 12 inches maximum in field, 8 inches at edges
  • •Three-coat system: Embedding/taping, filler/second coat, finish coat
  • •Level 4 finish standard: Smooth surface, ready for flat paint
  • •Level 5 finish: Critical light areas, requires skim coat over entire surface
Applies to:All gypsum board (drywall) installations

ASTM C840 - Application and Finishing of Gypsum Board(ASTM C840)

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Standard specification for drywall installation covering fastener types, spacing requirements, joint treatment methods, and quality standards for different finish levels.

Key Requirements:

  • •Fastener penetration: Minimum 5/8 inch into wood framing, 3/8 inch into steel
  • •Panel orientation: Perpendicular to framing members reduces sagging
  • •Joint offset: Stagger end joints minimum 24 inches between rows
  • •Corner beads: Metal or vinyl bead required at all outside corners
  • •Control joints: Required in walls exceeding 30 feet or ceiling exceeding 50 feet
Applies to:Standard residential and commercial drywall applications

ASTM C36 - Gypsum Wallboard Specifications(ASTM C36)

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Material specifications for gypsum wallboard including core composition, paper facing, edge treatment, and dimensional tolerances. Ensures consistent product quality.

Key Requirements:

  • •Core: Gypsum plaster with paper facing both sides
  • •Tapered edges: Long edges for tape and compound joint finishing
  • •Thickness tolerance: ±1/32 inch for standard sheets
  • •Moisture resistance: Regular vs. green board vs. purple board ratings
Applies to:Gypsum board product manufacturing standards

ASTM C1396 - Type X Fire-Resistant Gypsum Board(ASTM C1396)

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Specifications for fire-resistant gypsum board (Type X) with enhanced fire protection. Required by building codes for specific applications like garage ceilings and common walls.

Key Requirements:

  • •Type X designation: Passes 1-hour fire resistance test
  • •Special additives: Glass fibers and other materials enhance fire resistance
  • •Thickness: Typically 5/8 inch (1/2 inch Type X available but less common)
  • •Applications: Garage ceilings, furnace rooms, multi-family common walls
Applies to:Fire-rated assemblies and code-required fire protection

International Residential Code (IRC) R702 - Interior Covering(IRC 2021 Section R702)

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Building code requirements for interior wall and ceiling coverings including drywall thickness, attachment methods, and fire-resistance requirements for specific locations.

Key Requirements:

  • •Minimum thickness: 1/2 inch for 16-inch framing, 5/8 inch for 24-inch
  • •Garage ceiling: 5/8-inch Type X fire-rated drywall required
  • •Furnace room: Type X drywall on ceiling and walls containing equipment
  • •Multi-family common walls: Fire-rated assemblies per code
  • •Moisture areas: Water-resistant board required for tile backing in showers/tubs
Applies to:Residential drywall installations governed by IRC

GA-214 - Finishing Levels(Gypsum Association GA-214)

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Defines five levels of drywall finish from Level 0 (no finish) to Level 5 (highest quality). Specifies appropriate level for different lighting conditions and final finishes.

Key Requirements:

  • •Level 0: No taping, finishing, or accessories (temporary construction)
  • •Level 1: Tape embedded, no joint compound beyond tape (not for living spaces)
  • •Level 2: Tape embedded, thin coat compound (behind tile, texture)
  • •Level 3: Tape + 2 coats compound (ready for heavy texture)
  • •Level 4: Tape + 3 coats compound (flat paint, light texture) - STANDARD
  • •Level 5: Tape + 3 coats + skim coat entire surface (critical light, gloss paint)
Applies to:Specifying finish quality for contract documents and quality control

Standards Disclaimer: Standards and codes are subject to periodic updates. Always verify current requirements with local building authorities and professional engineers before beginning construction. Links provided are for reference only.

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Want to Learn More?

Gypsum Association standards, sheet sizes, joint compound coverage, and fastener spacing per IRC and ASTM C840.

Read the Drywall Materials Guide

How to Use This Calculator

  1. Enter room dimensions: Input wall and ceiling areas.
  2. Select sheet size: Choose 4x8, 4x10, or 4x12 sheets.
  3. Choose drywall thickness: Standard is 1/2" for walls, 5/8" for ceilings.
  4. Review materials: See sheets, joint compound, tape, and screws needed.

Drywall Material Standards

Standard 1/2" drywall weighs 1.6 lbs/sq ft. Fire-rated 5/8" Type X weighs 2.2 lbs/sq ft. Joint compound coverage: 350-400 sq ft per 5-gallon bucket.