ft
ft
in
Concrete needed
0.00 yd³
0.00 m³ · 0.0 ft³
| Bag size | Bags needed |
|---|
How the math works
Slab / footing: volume = length × width × depth. Column / post hole: volume = π × radius² × height. Stairs: approximated as cumulative blocks — step i has rise×(i×run)×width, summed across all steps.
Bag yields: 40 lb → 0.011 yd³ (0.30 ft³), 60 lb → 0.017 yd³ (0.45 ft³), 80 lb → 0.022 yd³ (0.60 ft³), 25 kg → 0.0125 m³, 30 kg → 0.015 m³.
The 10% waste factor accounts for uneven sub-grade, spillage and slightly over-ordering — best practice for residential pours.