Concrete Slab Calculator
Order 1.28-1.36 yd³
Plan volume: 1.23 yd³ (33.33 ft³). Range = NRMCA CIP 8 ordering allowance of 4-10% over plan.
Hiring it out? Finishing labor for this slab typically runs $164-$408 (4-6 crew-hours × $41-$68/hr modeled from BLS May 2024 OEWS medians median wage; see how we model this).
- Volume is plan geometry; NRMCA CIP 8 says order 4-10% over plan (subgrade, forms, spillage).
- A 1/8" thickness variation on a 4" slab is a ±3% volume swing; measure thickness honestly.
- Ready-mix increments and short-load fees are vendor practice; confirm with your plant.
Want quotes from local pros for this project? We’re gauging demand for a pro-matching service. No contractor network exists yet: this is a get-notified list, not a quote request.
How This Calculator Works
Volume = length × width × thickness ÷ 27 (yd³). The National Ready Mixed Concrete Association’s CIP 8 (Discrepancies in Yield) recommends ordering 4-10% over the plan-derived volume: form deflection, irregular subgrade, spillage, and air/settlement losses mean placed volume rarely equals plan volume. A 1/8″ thickness variation on a 4″ slab alone is a 3% volume swing, which is why we show a range, not a false-precision point. Bag yields are QUIKRETE technical-data-sheet values (60 lb ≈ 0.45 ft³). Labor context is modeled from BLS-published median wages times a published burden/markup band; see methodology for the full decomposition and as-of dates.