Joint compound is estimated by drywall area, not by sheet count — plan about one 4.5-gallon box per 12 sheets for tape plus three coats. This view returns that estimate; skim-coat (Level 5) finishes use noticeably more.
Field notes
Hang the ceiling first, then let the wall sheets support its edges — it's the difference between a job that holds and one that cracks along the top. Order 10% over: the offcut from around a door is rarely reusable elsewhere. For mud, the rule of thumb is one 4.5-gallon box per 12 sheets across tape and three coats, but skim-coat finishes burn through noticeably more.
How the drywall mud calculator works
The math behind the tool:
sheets = total area ft² ÷ 32 × (1 + waste%)Sources: Gypsum Association (gypsum board sizes and finishing).