About the Stucco Calculator
This stucco calculator converts a wall area into the number of premixed stucco bags to buy. Enter the gross wall area, subtract doors and windows, choose the coat system — traditional three-coat (about 7/8 inch), a two-coat or one-coat system (about 1/2 inch) or a finish coat only (1/8 inch) — and it returns the volume of material, bags, metal lath sheets and cost.
It is useful for re-stuccoing a house, covering a block garden wall or patching a large section, and for checking a contractor’s material list. Because stucco is applied by hand over irregular surfaces, a waste allowance of around 10% is included by default.
Bag yield varies by product, so the default of 0.8 cubic feet per 80-lb bag is a typical figure for premixed base-coat stucco — check the yield printed on your bag and adjust. The lath count assumes standard 27 × 96-inch sheets (18 sq ft) with about 10% extra for overlaps.
With the default inputs, the stucco bags needed is 86. Change any value above to recalculate instantly.
How to use the stucco calculator
- 1Measure each wall’s width × height and add them for the gross area.
- 2Add up the area of doors and windows to subtract.
- 3Choose the coat system (three-coat, one-coat or finish only).
- 4Check the bag label for yield and enter your price per bag.
- 5Read the bags and lath sheets needed.
Formula and method
Stucco is a thin slab of mortar, so the quantity is simply area × thickness. The net wall area (after subtracting doors and windows) in square feet is multiplied by the total coat thickness in inches divided by 12 to give cubic feet. A traditional three-coat system is about 3/8 inch scratch, 3/8 inch brown and 1/8 inch finish, totaling 7/8 inch.
A waste allowance covers material dropped, left in the mixer and extra thickness over uneven substrates. The total is divided by the bag yield in cubic feet and rounded up. Metal lath sheets are 27 × 96 inches (18 sq ft); the count adds 10% for side and end laps.
- thickness
- Total stucco thickness in inches
- yield
- Cubic feet of mixed stucco per bag
- waste
- Allowance for losses and uneven walls
Worked examples
Three-coat stucco on 1,000 sq ft of wall
After subtracting 150 sq ft of openings, 850 sq ft × 7/8 in ÷ 12 = 62 cu ft of stucco. With 10% waste that is 68.2 cu ft, or 86 bags at 0.8 cu ft each ($1,290), plus 52 sheets of lath.
Finish coat only on a 400 sq ft garden wall
A 1/8-inch finish coat over 360 sq ft is 3.75 cu ft, 4.1 cu ft with waste — six bags. No lath is needed when refinishing existing stucco or block.
One-coat system on a 2,200 sq ft house
1,900 sq ft at 1/2 inch is 79.2 cu ft, 87.1 cu ft with waste, so 109 bags. At 1/2 inch, this system uses about 43% less material than a 7/8-inch three-coat finish.
Frequently asked questions
How much area does a bag of stucco cover?+
An 80 lb bag yielding about 0.8 cu ft covers roughly 25 sq ft at 3/8 inch, about 11 sq ft at the full 7/8-inch three-coat thickness, and about 77 sq ft as a 1/8-inch finish coat — before waste.
How thick is a three-coat stucco system?+
Traditional three-coat stucco is typically about 7/8 inch: a 3/8-inch scratch coat, a 3/8-inch brown coat and a 1/8-inch finish coat. One-coat systems are usually around 3/8 to 1/2 inch plus a finish.
Do I need lath for stucco?+
Stucco over wood framing or sheathing needs a weather-resistive barrier and metal lath. Over clean, sound masonry or concrete block, stucco can often bond directly or with a bonding agent, so no lath is needed.
How much extra stucco should I buy?+
About 10% covers mixing leftovers, droppings and extra thickness on uneven walls. Rough block or wavy framing can push this to 15–20%.
How many bags of stucco for 100 square feet?+
At a 7/8-inch three-coat thickness, 100 sq ft needs about 7.3 cu ft of stucco — about 8 cu ft with 10% waste — 11 bags at 0.8 cu ft each once rounded up.