How do I calculate how much concrete I need?

For a slab: length × width × depth = volume. Convert to cubic yards: divide cubic feet by 27. Example: 10×10 slab 4 inches thick = 10×10×0.333 = 33.3 cu ft = 1.23 cu yards. Always add 10% for waste. 80-lb bag = 0.60 cu ft. 60-lb bag = 0.45 cu ft. One cubic yard ≈ 45 80-lb bags.

What is the concrete mix ratio?

Standard mix (4000 PSI): 1:2:3 (cement:sand:gravel) + water. Premixed bags at hardware stores are this ratio. For structural work: 5 bags cement per yard. For driveways: 6 bags per yard. Water/cement ratio: lower = stronger. Cure time: 24-48 hrs to walk, 7 days drive, 28 days full strength.

How do I calculate how much concrete I need?

For a slab: length × width × depth = volume. Convert to cubic yards: divide cubic feet by 27. Example: 10×10 slab 4 inches thick = 10×10×0.333 = 33.3 cu ft = 1.23 cu yards. Always add 10% for waste. 80-lb bag = 0.60 cu ft. 60-lb bag = 0.45 cu ft. One cubic yard ≈ 45 80-lb bags.

What is the concrete mix ratio?

Standard mix (4000 PSI): 1:2:3 (cement:sand:gravel) + water. Premixed bags at hardware stores are this ratio. For structural work: 5 bags cement per yard. For driveways: 6 bags per yard. Water/cement ratio: lower = stronger. Cure time: 24-48 hrs to walk, 7 days drive, 28 days full strength.

Concrete Calculator — How Much Concrete Do You Need?

Free concrete calculator. Enter dimensions of a slab, footing, or column to get volume in cubic yards, cubic meters, and 60 or 80 lb bag count. Includes 10% waste factor.

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