How Much Sand, Cement and Gravel for a 1,000 Sq Ft Slab (USA 2026)

Start with wet volume, not area

Every slab quantity takeoff begins with the same number: wet (placed) volume. Multiply the slab area by the finished thickness in feet, then convert to cubic yards by dividing by 27.

For 1,000 sq ft at 4 inches: 1,000 x (4 ÷ 12) = 333.3 cubic feet, or 12.35 cubic yards. At 6 inches: 1,000 x 0.5 = 500 cubic feet, or 18.52 cubic yards. Those two numbers drive everything that follows.

• 4 in slab, 1,000 sq ft = 333.3 cu ft = 12.35 cu yd
• 5 in slab, 1,000 sq ft = 416.7 cu ft = 15.43 cu yd
• 6 in slab, 1,000 sq ft = 500.0 cu ft = 18.52 cu yd

Convert wet volume to dry volume (the 1.54 factor)

Loose sand, gravel and cement lose bulk volume when they are mixed and compacted — voids fill with paste and water. The standard planning allowance is to multiply wet volume by 1.54 to get the dry volume of combined materials.

For the 4-inch slab: 333.3 x 1.54 = 513.3 cubic feet of dry material. For the 6-inch slab: 500 x 1.54 = 770 cubic feet.

Split dry volume by mix ratio

A 1:2:4 nominal mix (roughly 2,500–3,000 psi for residential flatwork) has 7 total parts: 1 cement, 2 sand, 4 gravel. Divide dry volume by 7, then multiply by each share.

For the 4-inch slab, 513.3 ÷ 7 = 73.3 cu ft per part. Cement = 73.3 cu ft, sand = 146.7 cu ft, gravel = 293.3 cu ft. Cement bag count uses bag yield, not bag weight: a 94 lb sack of Portland cement yields about 1.0 cu ft loose, so 73.3 cu ft ≈ 74 sacks.

Add waste, over-dig and thickness variation

Subgrade is never perfectly flat. On a graded and compacted base, add 5% for placement waste; on a rough or hand-dug base, 10% is safer. A half-inch of average over-dig across 1,000 sq ft is 41.7 cu ft — an extra 1.5 cubic yards you will pay for whether you planned it or not.

Screeding to string lines or wet-setting screed pipes is the cheapest way to control this. It costs an hour of labor and routinely saves a yard of concrete.

When to stop bagging and order ready-mix

Seventy-four sacks of cement plus 16 tons of gravel is not a wheelbarrow job. As a rule of thumb, past roughly 2 cubic yards a mixer becomes painful, and past about 10 cubic yards ready-mix is almost always cheaper once you price labor, mixer rental, aggregate delivery and the risk of cold joints.

A 1,000 sq ft slab at any thickness is firmly in ready-mix territory. Use the site-mix numbers above to sanity-check the batch plant quote rather than to plan a hand mix.

• Order in one continuous pour where possible to avoid cold joints
• Confirm truck spacing — 8–10 cu yd per truck is typical
• Ask for short-load fees up front; they can be $80–$180 per truck

Reinforcement and vapor barrier come out of the same takeoff

While you have the area open, price the rest of the assembly. A 1,000 sq ft slab typically needs 1,100 sq ft of 6-mil poly (10% lap allowance), roughly 11 sheets of 6x6 W1.4 welded wire mesh, or about 700 linear feet of #4 rebar at 18 in on center each way plus chairs.