Stucco Calculator
Estimate stucco for a wall in two-coat or traditional three-coat work: 80-lb base coat bags by thickness, plus finish coat bags.
Two systems, one wall
Traditional stucco is three coats over metal lath: a 3/8 in scratch coat, a 3/8 in brown coat and a 1/8 in finish coat — 7/8 in in all. Over solid masonry, two coats do the same job: about 1/2 in of base and the same finish. This calculator figures the base coats by volume from an 80-lb bag's published yield (about 0.65 cu ft) and the finish coat at its published coverage of about 110 sq ft per 80-lb bag at 1/8 in.
Base bags = wall area × base thickness ÷ bag yield (0.65 cu ft) · Finish bags = wall area ÷ 110 sq ft per bag
Example: a 100 sq ft wall in three-coat work needs 6.25 cu ft of base — 9.6 bags exactly, 11 bags with the 10% allowance — plus 1 bag of finish coat.
Coats and curing
| Coat | Thickness | Job it does |
|---|
| Scratch | 3/8 in | Keys into the lath, scored to grip the next coat |
| Brown | 3/8 in | Levels and builds the plane of the wall |
| Finish | 1/8 in | Color and texture — the coat you see |
Stucco fails by rushing, not by arithmetic: each base coat needs moist curing (48 hours is the standard minimum) before the next goes on, and the finish wants the brown coat cured a week. Buy for the whole wall in one order — finish coat color varies between production runs, and a wall finished from two lots can show the seam forever.
Frequently asked questions
How much area does one 80-lb bag of stucco cover?
At 3/8 in thick, about 21 sq ft for base coat; figure half that per coat when two base coats stack to 3/4 in. Finish coat goes much further — roughly 110 sq ft per bag at its 1/8 in skim.
Can stucco go straight onto concrete block?
Yes — masonry is the classic two-coat substrate; the block sucks moisture fast, so dampen the wall first and expect the first coat to drink. Wood-framed walls need paper and lath and the full three coats.
Why does my wall area need the waste allowance?
Stucco drops, rebounds off the wall and sticks to the hawk and trowel; 10% is the trade's normal loss. Textured finishes that are troweled back off and reworked waste a little more.
Is stucco the same as render or EIFS?
Render is the same family by a British name, figured identically. EIFS is a different system entirely — insulation board with a thin synthetic finish — and none of these bag rates apply to it.
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