Drywall Calculator

How to measure for drywall

Wall area is 2 × (length + width) × ceiling height. Don't subtract doors and windows for material ordering — the cutouts generate waste, and the "savings" roughly cancel out. For the ceiling, add length × width. A 12×12 room with 8-foot ceilings is 384 sq ft of walls plus 144 of ceiling: 528 sq ft, or 17 sheets of 4×8 before waste.

Choose 4×12 sheets when you can handle them (they need two people and a drywall lift for ceilings). Longer sheets mean fewer butt joints — and butt joints are where amateur finishing shows. For ceilings, always use 5/8" sheets; for walls, 1/2" is standard, 5/8" where fire code requires it (garages, furnace rooms).

Hanging tips

• Hang horizontally. Sheets span more studs, tapered edges land at comfortable height, and you get fewer butt joints than vertical hanging.
• Ceilings first, then walls. Wall sheets tucked under the ceiling sheets support the ceiling edges.
• Stagger butt joints between rows — never let four corners meet at one point.
• Screw pattern: every 12" on walls, every 12" on ceilings (every 16" max), set just below the surface without breaking the paper. A drywall screw gun with depth control is worth every penny.
• Cut outlets with a spiral saw after hanging the sheet — faster and cleaner than pre-measuring. Shut off the circuit first.
• Rent a lift for ceilings. A $50/day drywall lift turns a miserable two-person struggle into a one-person job.

Finishing: where the skill lives

Hanging is carpentry; finishing is craft. The standard is three coats: tape coat (embed paper tape in all-purpose compound), fill coat (wider, with lightweight compound), finish coat (widest, feathered). Let each coat dry fully — rushing causes bubbles and shrinkage cracks.

Know your finish level: Level 4 (two finish coats) suits flat and eggshell paint in normal light. Level 5 adds a full skim coat for glossy paint, large walls, or harsh raking light from windows — it roughly doubles finishing labor, so specify it in quotes explicitly.

Mud choice matters: all-purpose for taping (strongest bond), lightweight topping for finish coats (easier sanding). Setting-type compound (20/45/90 minute) for patches and first coats when you're in a hurry — it hardens chemically and won't shrink.

What affects drywall cost

Materials are cheap: 4×8 sheets run $12–$18, so a 12×12 room's drywall is under $300. Labor is the job: hanging runs $1–$2/sq ft, finishing another $1–$2.50 — a finished 12×12 room typically costs $1,500–$3,000 professionally done.

Level 5 finish, textured ceilings, curved walls, and patch-heavy remodels push costs up. Small jobs carry minimums ($300–$500) that make per-square-foot math misleading — batch your drywall work together when you can.

Common drywall mistakes to avoid

• Hanging before inspections. Electrical and plumbing rough-in must be inspected before you cover walls — a failed inspection means cutting open finished work.
• Breaking the paper with screws. Drive screws just below the surface; torn paper has no holding strength and pops later. Use a screw gun with a depth clutch.
• Rushing the coats. Each coat must dry completely before the next. Wet compound over wet compound traps moisture, causing bubbles and shrinkage cracks.
• Skipping the sand-between. A quick pole-sand between coats is what separates flat walls from wavy ones — five minutes per sheet, enormous payoff.