How to measure a wall for stucco
Multiply each wall's length by its height, add the walls together, and take off the windows and doors. Gable ends count as a triangle, half the base times the height. Then work out what you are covering, because the base decides everything. Metal lath takes more material than block does.
The thicknesses here come from Table 4 of ASTM C926, the standard the IRC points to in R703.7. On vertical work, three coats over metal lath are 3/8, 3/8 and 1/8 inch, which comes to 7/8 inch. On masonry or cast concrete, they are 1/4, 1/4 and 1/8 inch, or 5/8 inch. We read a 2011 copy on a Florida Building Commission page, and newer editions exist.
Bags are from Quikrete, since each brand's yield is its own. An 80 pound bag of base coat yields about 0.75 cubic feet, which is where 24 square feet at 3/8 inch comes from. Its table gives a range of 20 to 24, and it says coverage varies with thickness and waste. We show both ends, and the larger count is what to plan on.
A worked example
Here is a wall 40 feet long and 9 feet high with 40 square feet of openings, in three coats over metal lath. These lines come from the same formula the calculator above runs.
320 sq ft, three coats over metal lath
- 40 × 9 − 40 = 320 sq ft
- Base coats: 28 to 32 bags
- 320 ÷ 70 = 4.57, so 5 bags of finish coat
- At most 37 bags in total
- Metal lath: 320 sq ft before laps
We read no figure for how much metal lath is lost to laps, so add what your supplier says. If you are comparing cladding, the siding calculator measures the same wall, and a stucco wall that needs a coat of color can be priced with the exterior painting calculator.
Stucco thickness by system
The coat thicknesses are from ASTM C926. The bags are our own arithmetic from Quikrete's yield, for 100 square feet, at the low end of its coverage and with each coat rounded up to whole bags.
| System | Coats, in inches | Total | Base bags per 100 sq ft | Finish bags per 100 sq ft |
|---|---|---|---|---|
| Three coats over metal lath | 3/8 + 3/8 + 1/8 | 7/8 in | 10 | 2 |
| Three coats on masonry or concrete | 1/4 + 1/4 + 1/8 | 5/8 in | 8 | 2 |
| Three coats, metal lath over a solid base | 1/2 + 1/4 + 1/8 | 7/8 in | 11 | 2 |
| Two coats on masonry | 3/8 + 1/8 | 1/2 in | 5 | 2 |
| Two coats on cast concrete | 1/4 + 1/8 | 3/8 in | 4 | 2 |
| One-coat product | 3/8 | 3/8 in | 5 | 0 |
Mistakes when estimating stucco
- One thickness for every wall. Masonry takes 5/8 inch and metal lath takes 7/8 inch, so choose the base first.
- Trusting a flat rate on rough block. ASTM C926 says thickness on masonry need not be uniform, so uneven walls use more.
- Mixing too much. Quikrete says not to mix more than you can use in 1 hour.
- Working in the wrong weather. Quikrete says not above 100 F or if below 40 F is expected within 24 hours, and to protect it for 48 hours.
- Handling it bare. Quikrete's sheet warns that wet mix can cause severe skin burns. Wear gloves and eye protection.
Questions
How many bags of stucco per square foot?
About one 80 pound bag per 20 to 24 square feet at 3/8 inch, on Quikrete's table. At 1/2 inch that drops to 15 to 18, and at 3/4 inch to 10 to 12. A finish coat at 1/8 inch covers about 70 square feet a bag.
How thick is three-coat stucco?
About 7/8 inch over metal lath, as 3/8, 3/8 and 1/8 inch coats, by ASTM C926. On masonry or cast concrete, it is about 5/8 inch, as 1/4, 1/4 and 1/8 inch. We read the 2011 copy of that standard, and newer ones exist.
How much stucco do I need for 1,000 square feet?
About 99 to 115 bags of 80 pounds for three coats over metal lath. That is 84 to 100 bags of base coat and 15 of finish coat, on Quikrete's figures. Over masonry, thinner coats bring that down, so choose your system above.
What is Quikrete stucco coverage per bag?
About 20 to 24 square feet at 3/8 inch for its 80 pound base coat, which yields about 0.75 cubic feet. Its one-coat product is the same at 3/8 inch. Quikrete says all coverages are approximate and vary with thickness and waste.
How thick is stucco on block?
About 5/8 inch for three coats, or 1/2 inch for two, by ASTM C926. The IRC gives a 1/2 inch minimum on masonry. C926 also says thickness on masonry need not be uniform, so a rough block wall may take more material than this.
How many coats does stucco need?
At least three over metal or wire lath, by IRC R703.7.2, and two over masonry, concrete or treated wood. One-coat products rely on their own evaluation reports, such as IAPMO ER-455 for Quikrete's, which is not in ASTM's table.
This stucco amount is an estimate from Quikrete's yields, which it calls approximate, so check the label on your own mix. Uneven masonry drinks more than a flat wall. A bag count will not keep a wall dry: the water-resistive barrier and weep screed decide that, so have the local building department look over those details.
Sources and review
- ASTM C926-11a, on a Florida Building Commission copy, ASTM International, 2011.
- Scratch and Brown base coat stucco 1139, Quikrete, 2021.
- Stucco selector guide, Quikrete, no date printed, file details 2025.
- IRC 2021 chapter 7, wall covering, International Code Council, via UpCodes, 2021.
Checked in November 2026. Spotted a wrong number? Report it and it goes in the corrections log.
How this is calculated
Every figure below is read from the code that produces the answer, so what is written here is what the calculator ran. The constants were last checked against their sources in November 2026.
The arithmetic
Base coat
Bags = Area × Thickness ÷ 12 ÷ 0.75, for each coat
- 0.75
- Cubic feet from an 80 pound bag, by Quikrete
Worked through: 240 × 0.375 ÷ 12 ÷ 0.75 = 10
Finish coat
Bags = Area ÷ 70
- 70
- Square feet per bag at 1/8 inch, by Quikrete
Worked through: 320 ÷ 70 = 4.57
The constants, and where they come from
COAT_THICKNESS_INCHES
Published range, narrowedThickness of each coat by system, on vertical work
- three-metal
- 0.375, 0.375, 0.125
- three-masonry
- 0.25, 0.25, 0.125
- three-solid
- 0.5, 0.25, 0.125
- two-masonry
- 0.375, 0, 0.125
- two-concrete
- 0.25, 0, 0.125
Applies to: The 2011 edition, on a Florida Building Commission copy. Newer editions exist and were not read
Source: ASTM C926-11a, on a Florida Building Commission copy, ASTM International, published 2011, read 2026-11. This source is about 15 years old, and it is the one the figure rests on.
Also from: IRC 2021 chapter 7, wall covering, International Code Council, via UpCodes, published 2021, read 2026-11.
We read ASTM C926-11a Table 4, and not the current edition. The IRC says three coats over metal or wire lath, and two over masonry, concrete or treated wood.
ONE_COAT_INCHES
Published range, narrowedLeast thickness of a one-coat product, in inches
Applies to: Quikrete's No. 1200-80, under an IAPMO report we did not read
Source: Stucco selector guide, Quikrete, published 2025-01, read 2026-11.
A one-coat system is not in ASTM's table, and it relies on IAPMO ER-455 as Quikrete cites it. Other one-coat products have their own reports.
BAG_YIELD_CUBIC_FEET
Published figureWhat an 80 pound bag of base coat yields, in cubic feet
Applies to: Quikrete's Scratch and Brown base coat, mixed as directed
Source: Scratch and Brown base coat stucco 1139, Quikrete, published 2021-10, read 2026-11. This source is about 5 years old, and it is the one the figure rests on.
This reproduces the top of Quikrete's table: 24 square feet at 3/8 inch, 18 at 1/2 inch and 12 at 3/4 inch. Other brands will differ.
LOW_COVERAGE_SHARE
Published range, narrowedLow end of Quikrete's coverage, as a share of its yield
Applies to: Our reading of its coverage table
Source: Scratch and Brown base coat stucco 1139, Quikrete, published 2021-10, read 2026-11. This source is about 5 years old, and it is the one the figure rests on.
Quikrete's table gives 20 to 24 at 3/8 inch and says coverages vary with thickness and waste. The low end is about 17 percent below the yield, and acts as a waste range.
FINISH_COVERAGE_SQ_FT
Published figureWhat an 80 pound bag of finish coat covers at 1/8 inch, in square feet
Applies to: Quikrete's No. 1201 and 1202 finish coats
Source: Stucco selector guide, Quikrete, published 2025-01, read 2026-11.
Quikrete's selector guide gives 70 square feet per bag at the minimum finish thickness of 1/8 inch. A textured finish may use more.
INCHES_PER_FOOT
DefinitionalInches in one foot
Applies to: Definitional, everywhere
True by definition, so there is nothing to cite. The derivation is below.
Twelve inches make a foot by definition, so a coat's thickness in inches is divided by 12 to give a volume in cubic feet.
What the labels mean
- Published range, narrowed:
- a source publishes a range and this calculator uses a representative value from it.
- Published figure:
- taken directly from the source named beside it.
- Definitional:
- true by definition, like the number of inches in a foot, so there is nothing to cite.
If a figure here looks wrong, it may be. Tell us what you found and we will check it against the source and publish a correction if it needs one. How constants are chosen and how often they are reviewed is set out in our methodology.
How to use the stucco calculator
- 1
Measure the wall's length and height
- 2
Add up the windows and doors
- 3
Choose what the stucco goes on
- 4
Read the bags for each coat
- 5
Check the barrier and weep screed details locally
What this calculator assumes
Every estimate here rests on the assumptions below. Where your job differs from one of them, the figure will differ too.
- Coat thicknesses are nominal, from a 2011 copy of ASTM C926
- Bags use Quikrete's yields, and other brands differ
- Lath area is the wall area, as we read no figure for laps
- The high bag count is the low end of Quikrete's coverage
Pro tips
- Do not apply above 100 F, or below 40 F within 24 hours, by Quikrete
- Protect new work from rain, snow and freezing for 48 hours
- Keep the weep screed at least 4 in above earth, by the IRC