Stucco Calculator
Ten by ten feet, with 3/8 inch scratch, 3/8 inch brown, and 1/8 inch finish, is 7.29 cubic feet and 8 bags at a 1 cubic foot example yield.
Last updated . Scratch thickness starts at three eighths. Brown matches it. Finish starts at one eighth.
A stucco calculator for three coats on a wall. Area times each thickness is the coat volume. Bags follow a yield you type, not a price and not a brand coverage.
A single cement-and-sand coat: plaster calculator. Paint after the finish: paint calculator. Sheets instead of a coat: drywall calculator.
Three-coat volume and bags
Scratch, brown, and finish open on the ASTM C926 Table 4 nominal thicknesses for three-coat work over lath. Section 7.3.1 says those nominal thicknesses are neither a maximum nor a minimum, so each box can be replaced. One cubic foot per bag is only there so the bag line can be checked.
Results
Three nominal coats, then bags
A 10 by 10 foot wall is 100.00 square feet, 9.29 square meters. Scratch and brown at 3/8 inch are 3.125 cubic feet each, shown as 3.13. The 1/8 inch finish is 1.04166… cubic feet, shown as 1.04. Added before rounding, 7/8 inch on 100 square feet is 7.29166… cubic feet, shown as 7.29 cubic feet and 0.21 cubic meters. The rounded coat lines add to 7.30. The bag line uses the unrounded total. At an example yield of 1 cubic foot per bag, that is 8 bags.
Those three thicknesses are the ASTM C926 Table 4 nominal schedule for three-coat portland cement plaster over lath. The standard’s own note says a nominal thickness in that table is not a cap and not a floor, so the boxes can change. Two-coat plaster is limited to solid bases. The cement-and-sand plaster page on this site is a different takeoff: one thickness, a ratio, and cement bags. This page does not do that split, and it does not invent a bag price.
Worked wall
| Wall | Coats | Total | Yield | Bags |
|---|---|---|---|---|
| 10 × 10 ft | 3/8 + 3/8 + 1/8 in | 7.29 ft³ | 1 ft³ | 8 |
| 10 × 10 ft | 3/8 + 3/8 + 1/8 in | 7.29 ft³ | 2 ft³ | 4 |
| 20 × 10 ft | 3/8 + 3/8 + 1/8 in | 14.58 ft³ | 1 ft³ | 15 |
Stucco questions
How much stucco is on a 10 by 10 wall?
Leave length and height at 10 ft, scratch and brown at 0.375 in, finish at 0.125 in, and bag yield at 1 ft³. Area reads 100.00 ft² · 9.29 m². Scratch reads 3.13 ft³ · 0.09 m³. Brown reads 3.13 ft³ · 0.09 m³. Finish reads 1.04 ft³ · 0.03 m³. Total volume reads 7.29 ft³ · 0.21 m³. Bags reads 8.
Why do the coat lines add to 7.30?
Each coat line is rounded on its own. 3.13 + 3.13 + 1.04 = 7.30, while the total reads 7.29. The unrounded sum is 100 × 7/8 ÷ 12 = 7.2916… cubic feet, and that unrounded sum is what the bag count uses. At 1 cubic foot per bag, the count is 8.
What if the bag yield is cleared?
Clear the bag yield and leave the wall and the three thicknesses. Area, scratch, brown, finish, and total volume stay on the 10 by 10 figures. Bags reads Enter a bag yield.
What if the bag yields 2 cubic feet?
Type 2 into the bag yield and leave the unit on ft³. Bags reads 4. Total volume still reads 7.29 ft³ · 0.21 m³.
What does a 20 by 10 wall need?
Set the length to 20 ft and the bag yield back to 1. Area reads 200.00 ft² · 18.58 m². Scratch reads 6.25 ft³ · 0.18 m³. Brown reads 6.25 ft³ · 0.18 m³. Finish reads 2.08 ft³ · 0.06 m³. Total volume reads 14.58 ft³ · 0.41 m³. Bags reads 15.
Is this the plaster calculator?
No. The plaster page is one cement-and-sand coat, with a mix ratio and a dry-volume factor. This page is three coats over lath, using the ASTM C926 Table 4 nominal thicknesses, and a bag yield you type. It does not split cement and sand.
Are 3/8, 3/8, and 1/8 a maximum?
No. ASTM C926 section 7.3.1 says the Table 4 nominal thicknesses are not a maximum and not a minimum. The 7/8 inch total is the usual three-coat figure over lath: two 3/8 inch coats plus a 1/8 inch finish. Two-coat work is for solid bases. The three boxes stay editable so a different spec can be typed.