How to use it
- Enter the slab length in feet.
- Enter the slab width in feet.
- Enter the thickness in inches.
- Read the cubic yards, bag count, and cubic feet results.
What it does – The Cement Calc Calculator takes your slab dimensions (length, width, thickness) and instantly returns three values you need for ordering concrete: total cubic yards, the number of standard 80‑lb bags, and total cubic feet.
Why it matters – Knowing cubic yards helps you compare contractor quotes, while the bag count tells you exactly how many bags to buy if you’re mixing on‑site. Cubic feet is useful for estimating fill for small projects or checking against material specs.
How to read the results – Cubic yards is the volume in 27‑ft³ units, the industry standard for delivery. Bags is the volume divided by 0.6 ft³ (the yield of one 80‑lb bag). Cubic feet shows the raw volume before conversion.
Example – A 10 ft × 5 ft slab 4 in thick yields 0.62 yd³, 28 bags, and 16.7 ft³.
Pro tips
- Add 5‑10% extra for waste and spillage.
- Round bag count up to the next whole bag.
- Order a full bag rather than partial to avoid shortages.
- Double‑check thickness units; inches must be converted to feet internally.
Real-life examples
- A homeowner estimating concrete for a new patio.
- A contractor preparing a quote for a driveway slab.
- A DIY gardener planning a raised garden bed base.
Case study
Mike needed a 12 ft × 8 ft patio 4 in thick. He entered the numbers, got 1.18 yd³ and 20 bags (rounded up), and ordered exactly that amount. The delivery arrived perfect, eliminating over‑order waste and saving him $120.