Stucco Calculator
Calculate bags of stucco mix from wall area and coat thickness for scratch, brown, and finish coats.
Returns bag count and coverage per 80-lb bag.
Stucco coverage calculations determine how much material you need to cover a wall surface to the specified coat thickness. Traditional stucco is applied in three coats (scratch coat, brown coat, and finish coat); EIFS (synthetic stucco) is a two-coat system. Each coat has a different thickness and coverage rate.
Total stucco volume formula: Volume = Surface Area × Total Thickness
Bags needed formula: Bags = Volume ÷ Yield per Bag
Where:
- Surface Area — total wall area in square feet or square meters (subtract windows and doors)
- Total Thickness — sum of all coat thicknesses (traditional 3-coat: 3/8" + 3/8" + 1/8" = 7/8" = 0.073 ft)
- Yield per Bag — varies by product; typically 0.45–0.55 cubic feet per 80 lb bag
- Waste Factor — add 10–15% for cuts, corners, and mixing losses
Traditional 3-coat stucco thicknesses:
- Scratch coat (first): 3/8 inch (9.5 mm)
- Brown coat (second): 3/8 inch (9.5 mm)
- Finish coat (third): 1/8 inch (3 mm)
- Total system thickness: 7/8 inch (22 mm)
Typical coverage rates per 80 lb bag:
- Scratch/brown coat mix: ~35–40 sq ft at 3/8" thickness
- Finish coat: ~50–60 sq ft at 1/8" thickness
Mix ratio (by volume) for traditional stucco:
- Scratch coat: 1 part Portland cement : 3 parts sand
- Brown coat: 1 part Portland cement : 4 parts sand
- Finish coat: 1 part white Portland : 3 parts marble sand + pigment
Worked example: Stucco a 600 sq ft exterior wall (after subtracting windows/doors). Full 3-coat system.
- Scratch coat bags: 600 sq ft ÷ 37 sq ft/bag = 16.2 → 18 bags (with 10% waste)
- Brown coat bags: 600 sq ft ÷ 37 sq ft/bag = 18 bags
- Finish coat bags: 600 sq ft ÷ 55 sq ft/bag = 12 bags
Total: ~48 bags of stucco products. At $15–$20 per bag, material cost ≈ $720–$960 before sand, cement, and finish pigment.