Concrete Slab & Footing Calculator – Wanjaaro Material & Cost Calculator
Calculate volume in cubic yards, pre-mixed bags (40, 60, 80 lb), and rebar grid requirements. Free, instant deterministic calculations with waste margin, material takeoffs, and contractor cost breakdown.
Category: Concrete & Masonry
Last Modified: 2026-10-13
Available Building Material Calculators
- Concrete Slab & Footing Calculator – Calculate volume in cubic yards, pre-mixed bags (40, 60, 80 lb), and rebar grid requirements.
- Brick & Mortar Calculator – Calculate total modular, king, or queen bricks, mortar bags (Type N/S), and tons of sand.
- Concrete Block (CMU) Calculator – Estimate standard CMU blocks, core-fill grout volume, mortar bags, and vertical rebar.
- Wall Framing & Stud Calculator – Calculate common studs, double top plates, bottom sill, headers, corners, and board feet.
- Plywood & OSB Sheathing Calculator – Determine 4x8 / 4x10 sheets for walls, subfloors, and roof decks plus framing nail counts.
- Drywall & Sheetrock Calculator – Calculate 4x8, 4x10, 4x12 drywall sheets, joint compound buckets, screws, and tape rolls.
- Paint & Primer Coverage Calculator – Estimate gallons of wall/ceiling paint and primer with window and door deduction.
- Roofing Shingle & Pitch Calculator – Calculate roofing squares, architectural bundles, pitch multipliers, felt, and ridge caps.
- Tile, Grout & Flooring Calculator – Calculate square footage, tile boxes with waste, grout weight (lbs), and thin-set bags.
- Construction Cost & Budget Estimator – Estimate total project budget with material subtotal, labor rates, GC markup, and contingency.
Frequently Asked Questions
How many 80 lb bags of concrete are in a cubic yard?
One cubic yard of concrete equals 27 cubic feet. A standard 80 lb bag yields approximately 0.60 cubic feet of mixed concrete. Therefore, 45 bags of 80 lb concrete are required to make one cubic yard (27 ÷ 0.60 = 45 bags). With a recommended 10% waste and spillage margin, order 50 bags.
What thickness should a residential concrete slab be?
Residential concrete sidewalks, patios, and shed floors are typically poured 4 inches thick (using 2x4 formwork). Driveways and vehicle parking slabs intended for passenger trucks and SUVs should be 5 to 6 inches thick with #4 (1/2") rebar reinforcement on 18-inch centers.
How much does ready-mix bulk concrete cost compared to bag mix?
Delivered ready-mix concrete from a transit mixer typically costs $135 to $165 per cubic yard (often with a short-load charge if ordering under 4 to 5 yards). 80 lb bags cost $6.00 to $7.00 each, totaling $270 to $315 per cubic yard in materials. For jobs over 1.5 to 2 cubic yards, ready-mix delivery is generally both cheaper and significantly less labor-intensive.