Drywall Calculator

Measure each room's length, width, and wall height, and add a section for it. For an irregular layout, add one section per rectangular room or area — the calculator sums their areas automatically before any rounding happens.

Turn on “Include ceiling?” for a room whose ceiling will also be drywalled — its area (length × width) is added to that room's wall area. Leave it off for a wall-only estimate, such as a room that already has an existing ceiling.

Add each door or window's actual width and height inside its room using “Add door or window.” The calculator multiplies width × height and subtracts the total from that room's gross area — no standard door or window size is assumed, since actual openings vary by project.

4×8 ft is the Imperial default. 4×10 and 4×12 ft are also available as additional presets. Metric presets are 1200×2400, 1200×2700, and 1200×3000 mm — genuinely different standard product sizes, not a unit conversion of the Imperial sizes. Availability varies by product and market, so you can also enter a custom panel size directly.

This calculator starts with a 10% planning allowance for cuts and offcuts. It is an editable estimating assumption, not a universal recommendation. Set it to 0% if you don't want an allowance, or adjust it for your project's layout and complexity.

Use “Add sloped section” in Advanced options for drywall area from a gable end or angled ceiling that isn't already captured by a rectangular room's dimensions — enter its base and height, and the calculator adds ½ × base × height to your project total. Don't add a section for area that's already counted in a room's wall or ceiling area, or it will be double-counted.

Add one section per room. Each room's net area (gross area minus its own openings) is calculated in full, every room and sloped section is added together at full precision, and only then is the order allowance applied once to the combined total, followed by rounding up to a whole number of panels. Nothing is rounded room-by-room along the way — rounding each room separately and adding the results can require more panels than necessary.

Joint compound coverage varies by product, number of coats, and finishing level — there is no single reliable coverage figure that applies to every product, so this calculator never assumes one. Turn on the joint compound section in Advanced options, enter your specific product's stated coverage per package, and the calculator divides your project's net drywall area by that coverage, rounding up to a whole package.

No. Panel thickness (such as 1/2" vs. 5/8") affects product selection, fire rating, and installation requirements — it does not change this area-based quantity formula, which is why thickness isn't an input here.

This calculator estimates drywall area, then divides by your panel's coverage — it can't determine the optimal real-world sheet layout for your specific room. The same wall area can require a different actual number of sheets depending on panel dimensions, orientation, and how seams are planned around corners and openings. Panel layout is a real-world installation decision this calculator doesn't make for you.

• Joint tape — actual requirement depends on real seam length, which depends on panel layout and orientation, not area alone.
• Screws, nails, or other fasteners — requirements depend on framing spacing/material, panel orientation, and manufacturer instructions.
• Structural framing, fire-rated or moisture-resistant assembly design.
• Soundproofing (STC) system design.
• Fastening schedules or building code compliance of any kind.
• Labor, delivery, disposal, or taxes.

Follow your project drawings, your specific product's manufacturer instructions, and a qualified professional for all of the above — this calculator estimates drywall panel (and, optionally, joint compound) material quantity only.