How to use it
- Enter length in feet
- Enter width in feet
- Enter thickness in inches
- Read cubic yards, bags and cubic feet results
This tool converts the dimensions of any slab, footing or column into three practical units: cubic feet, cubic yards and the number of 80‑lb bags of mix. Knowing the exact volume prevents costly over‑ordering and avoids the frustration of running short mid‑project. The calculator first multiplies length, width and thickness (converted to feet) to get cubic feet, then divides by 27 to show cubic yards, the standard delivery unit. Finally it divides cubic feet by 0.6 ft³ per bag, giving a realistic bag count. Use the results to compare supplier quotes, schedule deliveries, and keep your budget on track. The output updates instantly, so you can tweak dimensions and see the impact in real time.
Pro tips
- Add 5‑10% extra for waste and spillage
- Round bag count up to the nearest whole bag
- Order bags in full pallets when possible for lower freight
- Double‑check thickness conversion – inches must be divided by 12
Real-life examples
- A homeowner pouring a 12 ft × 8 ft patio 4 in thick wants to know how many bags to buy
- A contractor estimating concrete for a 20 ft × 30 ft warehouse floor 6 in thick needs cubic yards for the supplier quote
- A DIYer building a raised garden bed 3 ft × 5 ft with a 2‑in concrete base wants the exact bag count
Case study
Mike needed a 10 ft × 10 ft patio at 4 in thickness. Using the calculator he saw 33.3 ft³, 1.23 yd³ and 56 bags. He ordered 56 bags, avoided a $150 overrun and completed the job on schedule.