How to use it
- Enter length in feet.
- Enter width in feet.
- Enter thickness in inches and click Calculate.
What it does – The calculator takes the length and width in feet and the slab thickness in inches, then instantly shows three values: total cubic yards of concrete needed, how many 80‑lb bags that translates to, and the raw cubic‑feet volume.
Why it matters – Knowing cubic yards helps you order the right amount of ready‑mix, while bag count is essential for DIY mixes. Accurate numbers prevent costly over‑ordering or shortfalls that delay projects.
How to read the results – Cubic yards are the standard delivery unit (1 yd³ = 27 ft³). The bag total is the cubic‑feet volume divided by 0.6 ft³ per bag, rounded up. Cubic feet gives a quick sense of the slab size.
Enter your dimensions, hit calculate, and the tool does the math so you can focus on site prep.
Pro tips
- Add a 10% waste allowance to cover spillage and variations.
- Round up the bag count; you can’t purchase a fraction of a bag.
- Order a few extra bags to ensure you have enough for uneven areas.
- Double‑check thickness conversion; inches must be converted to feet for volume.
Real-life examples
- Homeowner pouring a 12 × 10 ft patio 4 in thick wants exact bag count.
- Contractor estimating material for a 20 × 30 ft driveway 6 in thick.
- DIY enthusiast planning a garden stepping‑stone base 2 in thick.
Case study
Before using guesswork, Jane ordered 80 bags for a 12 × 10 ft patio and paid extra; after the calculator showed 67 bags, she ordered the exact amount, saving cost and space.