How much stucco do you need?
Add your walls and pick the coats, get cubic feet and bags instantly.
0.375 in = 3/8 in, 0.125 in = 1/8 in. Three coats over metal lath come to about 7/8 in in all (PCA).
0.75 ft³ is QUIKRETE's yield for an 80 lb bag; 10% extra is an example.
How much stucco do I need?
Multiply the wall area, minus doors and windows, by each coat's thickness in feet, add some extra, and divide by the bag yield. Example: walls of 40 × 9 and 30 × 9 ft are 630 ft²; take out 60 ft² of openings and 570 ft² remain. A 3/8-inch scratch coat is 570 × 0.375 ÷ 12 = 17.8 ft³ — 19.6 ft³ with 10% extra, or 27 bags at 0.75 ft³. With a 3/8-inch brown coat and a 1/8-inch finish coat it comes to 53 bags of base coat and 9 bags of finish.
How thick is three-coat stucco?
The Portland Cement Association puts three coats over metal lath at a total of 7/8 inch (22 mm) — scratch coat, brown coat and finish coat — and plaster applied directly to concrete or masonry at about 1/2 inch. The 2021 IRC (Table R702.1(1)) likewise asks for at least 7/8 inch outside over wire lath and 1/2 inch over masonry. The calculator starts at 3/8 + 3/8 + 1/8 inch; change each coat to match your plans.
How many square feet does a bag of stucco cover?
QUIKRETE's data sheets list about 0.75 ft³ from an 80 lb bag of Scratch and Brown Base Coat Stucco — 20 to 24 ft² at 3/8 inch, 15 to 18 ft² at 1/2 inch — and about 0.75 ft³ from an 80 lb bag of Finish Coat Stucco, roughly 70 ft² at 1/8 inch. The lower figures in each range allow for waste, which is why the calculator adds extra on top of the pure volume.
How many coats does stucco need?
Section R703.7.2 of the 2021 IRC calls for at least three coats over metal or wire lath, and at least two over masonry, concrete, treated or decay-resistant wood, or gypsum backing. Pick "Two coats" for a base coat and finish coat. So-called one-coat stucco is a proprietary system — QUIKRETE's One Coat Fiberglass Reinforced Stucco goes on at least 3/8 inch thick with the same coverage as its base coat, then gets a finish coat; follow its evaluation report.
Does the calculator include lath?
No — it counts the plaster only. The IRC (Section R703.7.1) requires corrosion-resistant lath per ASTM C1063, attached with nails or staples no more than 7 inches apart along the framing; buy it by the wall area plus the laps your lath maker specifies.
Sources: QUIKRETE product data sheets — Scratch and Brown Base Coat Stucco (No. 1139), Finish Coat Stucco (No. 1201), One Coat Fiberglass Reinforced Stucco (No. 1200); Portland Cement Association, “Repair of Portland Cement Plaster (Stucco)” (IS526, 2001); International Code Council, 2021 International Residential Code, Sections R703.7–R703.7.2 and Table R702.1(1). Siding instead? Use the siding calculator. How we check our calculators.