Choosing the Right Concrete Mix for Your Climate
Climate-specific concrete mix selection: cold weather accelerators, hot weather retardants, air entrainment for freeze-thaw, and sulfate-resistant options.
Read the guide →Concrete Calculator
Calculate cubic yards or bags of concrete needed for slabs, footings, columns, and tubes.
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How This Calculator Works
This concrete calculator estimates the volume of concrete you need for slabs, columns, or fence post holes in cubic yards, cubic feet, and 80-lb bags.
How it works:
- Volume formula: Length × width × depth (for slabs) or π × r² × depth (for round columns and post holes). All measurements in feet gives you cubic feet. Divide by 27 to get cubic yards.
- Bag count: An 80-lb bag of Quikrete or Sakrete makes approximately 0.6 cubic feet of finished concrete. Total cubic feet ÷ 0.6 = number of bags. Add 5-10% waste factor for spillage and uneven subgrades.
- Fence post mode: Post hole volume = π × (hole radius²) × hole depth, minus the volume of the post itself (post width × post width × hole depth for square posts).
Example: A 4×4 slab (4 ft × 4 ft × 4 in deep) = 4×4×0.333 = 5.33 cubic feet. At 0.6 cf per 80-lb bag, that's 8.9 bags — buy 10. See our concrete mix guide for strength grades and cold-weather placement tips.
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Ready-mix vs bagged concrete: cost comparison, the 90-minute pour window, cold joint prevention, and finishing timing.
Read the guide →Concrete Finishing Guide for DIYers
Concrete finishing techniques: floating vs troweling, surface compaction, curing timing for strength gain, and common defects.
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