Stucco calculator
Enter the wall area, take off openings and pick the stucco system to see how many bags of base coat and finish coat to buy.
Enter your measurements
More options: Extra
- Finish coat bags (80 lb)
- 3 bags
- Coats
- Scratch ⅜ in + brown ⅜ in + finish ⅛ in
- Wall area (net of openings)
- 160 sq ft
- One base coat bag covers (first coat)
- 21 sq ft
20 ft × 8 ft = 160 sq ft
Base coats: 160 sq ft × 0.75 in ÷ 12 + 10% ÷ 0.656 cu ft per bag (21 sq ft at ⅜ in) = 17 bags
Finish: 160 sq ft × 0.125 in ÷ 12 + 10% ÷ 0.729 cu ft (70 sq ft at ⅛ in) = 3 bags
- Keep each coat damp while it cures and give it time before the next — follow the bag’s timing. Don’t apply stucco in freezing weather; Quikrete says protect portland-based plaster from freezing for at least 24 hours.
Quick answers for common sizes
| Example | Answer |
|---|---|
| How many square feet does a bag of stucco cover | 20–24 sq ft per 80 lb bag of base coat at ⅜ in; finish coat about 70 sq ft at ⅛ in |
Bags for other wall areas (system as above)
| Wall length | Base coat bags | Finish coat bags (80 lb) | Wall area (net of openings) |
|---|---|---|---|
| 5 ft | 5 bags | 1 bag | 40 sq ft |
| 10 ft | 9 bags | 2 bags | 80 sq ft |
| 20 ft | 17 bags | 3 bags | 160 sq ft |
| 40 ft | 34 bags | 6 bags | 320 sq ft |
| 80 ft | 68 bags | 11 bags | 640 sq ft |
Stucco (portland cement plaster) goes on in coats. Over metal lath on a framed wall, the traditional system is three coats: a ⅜ in scratch coat, a ⅜ in brown coat and a ⅛ in finish coat — the thicknesses in Quikrete’s stuccoing guide. Directly on concrete block, which needs no lath, CMHA’s TEK 09-03A lists thinner systems: three coats of ¼ + ¼ + ⅛ in, or two coats of ⅜ + ⅛ in.
How far a bag goes
| Product (80 lb bag) | Yield | Coverage on the data sheet |
|---|---|---|
| Quikrete Base Coat Stucco | ≈ 0.75 cu ft | 20–24 sq ft at ⅜ in · 15–18 at ½ in · 10–12 at ¾ in |
| Quikrete Finish Coat Stucco | ≈ 0.75 cu ft | ≈ 70 sq ft at ⅛ in |
| Quikrete One Coat stucco | — | 20–24 sq ft at ⅜ in · 15–18 at ½ in |
base coat bags = area × (scratch + brown thickness in inches) ÷ 12 × (1 + extra) ÷ 0.656 (0.656 cu ft = 21 sq ft at ⅜ in per 80 lb bag) finish bags = area × finish thickness ÷ 12 × (1 + extra) ÷ 0.729
A worked example for 100 square feet is on how many square feet does a bag of stucco cover.
Mixing your own
Base coats can also be mixed from portland cement, lime and plaster sand. Quikrete’s Portland Cement data sheet lists an ASTM C926 scratch-and-brown blend of 1 part cement, ½ part hydrated lime and 4½–6 parts plaster sand by volume. Premixed bags are simpler for small walls.
Tips
- Scratch the first coat with a raking tool so the brown coat has something to grip.
- Keep each coat damp while it cures; stucco that dries too fast cracks.
- Bring the brown coat out flat with a straightedge — the finish coat is too thin to hide waves.
- Plan control joints and trim (casing beads, weep screeds) before the scratch coat goes on.
What you’ll need
- Mortar hawkBudget price
A flat board with a handle underneath that holds a load of mortar or stucco next to the work.
See options on Amazon (opens in a new tab) - Steel finishing trowelBudget price
For a smooth, dense finish on slabs, steps and countertops, and for stucco finish coats.
See options on Amazon (opens in a new tab) - Self-furred metal lathMid-range price
Gives stucco and stone veneer scratch coats something to grip over sheathing. Follow the maker’s fastener spacing.
See options on Amazon (opens in a new tab) - Drill mixing paddleBudget price
Mixes mortar, self-leveler, stucco and grout in a bucket. Use a low-speed, high-torque drill so the mix doesn’t fly.
See options on Amazon (opens in a new tab)
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Frequently asked questions
How many coats does stucco need?
Three over metal lath on a framed wall (scratch, brown, finish). On sound concrete block or concrete, two or three thinner coats are common — CMHA lists ⅜ + ⅛ in or ¼ + ¼ + ⅛ in.
How thick is stucco?
About ⅞ in in total for three coats over lath (⅜ + ⅜ + ⅛ in), and ½–⅝ in on masonry.
How much stucco per square foot?
Three-coat stucco over lath uses about 0.073 cu ft per square foot (⅞ in ÷ 12) — roughly 0.1 of an 80 lb bag of base coat and 0.014 of a finish bag, before waste.
Related guides
Sources
- Quikrete Scratch and Brown Base Coat Stucco (No. 1139) data sheet (opens in a new tab) — 80 lb bag yields about 0.75 cu ft; covers 20–24 sq ft at 3/8 in, 15–18 at 1/2 in, 10–12 at 3/4 in.
- Quikrete Finish Coat Stucco (No. 1201) data sheet (opens in a new tab) — 80 lb bag yields about 0.75 cu ft; about 70 sq ft at 1/8 in.
- Quikrete — Stuccoing project guide (opens in a new tab) — Over lath: scratch coat 3/8 in, brown coat 3/8 in, finish coat 1/8 in.
- CMHA (formerly NCMA) TEK 09-03A — Plaster and stucco for concrete masonry (opens in a new tab) — Table 4: on concrete masonry, three-coat 1/4 + 1/4 + 1/8 in (5/8 in) and two-coat 3/8 + 1/8 in (1/2 in).
- Quikrete Portland Cement data sheet (opens in a new tab) — Concrete mix 1 part cement : 2 parts sand : 3 parts gravel by volume; five to six 94 lb bags of cement per cubic yard of concrete; Type S and Type N mortar and ASTM C926 stucco blends.