How much drywall do you need?

At 500 sq ft using standard 4×8 sheets (32 sq ft each) with no waste allowance, you need 16 sheets — exactly matching the National Gypsum estimator chart. Add a 10% waste factor and you need 18 sheets to cover cuts and breakage.

The National Gypsum / USG rate is 0.009 gallons per sq ft for a standard 3-coat Level-4 finish (taping, coating, and finishing seams, corners, and fasteners — not a full skim). That is 4.5 gallons for 500 sq ft, or 9 gallons for 1,000 sq ft. Level-5 skim coat can need 5× more.

A standard USG 4.5-gal all-purpose pail at 0.009 gal/sqft covers 500 sq ft. Pails needed = ⌈ gallons ÷ 4.5 ⌉. For 500 sq ft that is 1 pail; for 1,000 sq ft it is 2 pails. The calculator derives pails from the gallon estimate so both numbers always agree.

The National Gypsum rate is 0.35 linear feet of tape per sq ft of drywall (350 ft per 1,000 sq ft). A standard USG 500-ft paper roll covers about 1,428 sq ft of drywall area. For 500 sq ft you need 175 ft — one roll.

On walls with 16-in on-center framing, you need about 32 screws per 4×8 sheet (1.0 screw/sq ft). Ceilings require tighter 12-in field spacing — about 36–42 screws per sheet (1.33/sq ft). For a mixed walls-and-ceiling project the blended rate is 1.25 screws/sq ft per the National Gypsum estimator chart.

A standard 1-lb box of #6 × 1¼-in coarse-thread drywall screws contains about 238 screws. Divide your total screw count by 238 and round up. For a 500 sq ft mixed-surface job you need 625 screws — 3 boxes.

4×12 sheets (48 sq ft) mean fewer seams, which reduces tape, mud, and finishing labor on large walls. The trade-off is weight and handling — a 4×12 half-inch sheet weighs roughly 77 lb vs 52 lb for a 4×8. A drywall lift is strongly recommended for ceilings with 4×12 boards.

The industry standard is 10% overage for most rooms. Bump to 15% for rooms with lots of angles, archways, or L-shaped walls that generate more off-cuts. The calculator applies waste before rounding up so the extra material is real, not just a rounding artifact.