How to use it
- Enter length in feet.
- Enter width in feet.
- Enter thickness in inches.
- Read cubic yards, bags and cubic feet results.
What it does – The calculator converts the dimensions of a slab (length, width, thickness) into three practical units: cubic feet, cubic yards, and the number of 80‑lb bags of mix (each bag ≈ 0.6 ft³). Why it matters – Knowing cubic yards helps you order the right amount of ready‑mix, while bag count guides DIY purchases and budgeting. How to read – The cubic‑feet value is the raw volume, divide by 27 for cubic yards, and divide by 0.6 for bag count. The tool also shows you how many whole bags to order, so you avoid shortfalls. You can round up the bag total to the nearest whole bag, and add a 10% waste allowance for spillage or uneven subgrade. The results update instantly as you tweak dimensions, making it easy to compare different slab sizes before committing to a purchase.
Pro tips
- Add 10% extra for waste and spillage.
- Round bag count up to the next whole bag to prevent shortages.
- Order ready‑mix by the cubic yard for larger jobs to save on delivery fees.
- Double‑check thickness conversion (inches to feet) before entering data.
Real-life examples
- A homeowner sizing a new garage floor slab.
- A contractor estimating concrete for a commercial patio.
- A DIYer planning a garden walkway with varying widths.
Case study
John needed a 12 ft × 10 ft patio 4 in thick. Using the calculator he saw he required 1.5 yd³ ready‑mix or 67 bags, ordered 70 bags, and finished without extra trips.