How to use it
- Enter length in feet.
- Enter width in feet.
- Enter thickness in inches.
- Click Calculate to see cubic yards, bags, and cubic feet.
What it does – The Ready Mix Concrete Calculator converts the dimensions of any slab, walkway, or pad into three useful units: cubic yards (what contractors quote), total bags of 80‑lb mix, and cubic feet (for on‑site checks). Why it matters – Ordering too little leads to project delays; ordering too much wastes money and space. How to read the results – Cubic yards is the volume you’ll give to a supplier. Multiply the bag count by 0.6 ft³ to verify it matches the cubic‑feet figure; if numbers differ, check your inputs. Enter your slab’s length, width, and thickness; the tool instantly computes the volume in cubic feet, then divides by 27 to give cubic yards, and finally divides by 0.6 to estimate the number of 80‑lb bags. The three results let you compare contractor quotes, plan storage, and confirm you have enough material before the pour. Remember that a 1‑inch increase in thickness adds roughly 0.083 cubic yards per 100 sq ft, so small changes can affect cost significantly. You can also use the bag count to schedule deliveries in multiples that fit your truck’s capacity.
Pro tips
- Add 5‑10% waste allowance to the bag total for cuts and spillage.
- Round up the bag count; you can’t buy a fraction of a bag.
- Order bags in full truckloads when possible to lower delivery fees.
- Double‑check thickness; a common mistake is entering inches as feet.
Real-life examples
- A homeowner plans a 12 ft × 10 ft patio 4 in thick and needs to know how many bags to order.
- A contractor estimates concrete for a 30 ft × 20 ft warehouse slab 6 in thick.
- A landscape designer sizes a 50 ft × 5 ft walkway 3 in thick for a commercial project.
Case study
Mike entered a 16 ft × 12 ft patio at 5 in thickness, got 0.9 cubic yards and 15 bags, ordered 16 bags, and completed the pour without a single shortfall, saving time and avoiding a costly reorder.