Ready Mix Concrete Bags Calculator

Calculate the cubic yards, bags of 80‑lb mix, and cubic feet you need for any slab instantly and free.

  • Free
  • No sign-up
  • Instant results

Loading calculator…

How to use it

  1. Enter length, width, and thickness in the fields provided.
  2. Press Calculate to see cubic feet, cubic yards, and bag count.
  3. Review the numbers and adjust dimensions if needed.

Enter the length, width, and thickness of your concrete pour. The calculator converts the dimensions to cubic feet, then divides by 27 to show cubic yards - the unit most contractors quote. It also divides the cubic‑foot total by 0.6, the yield of a standard 80‑lb bag, giving you the exact bag count. Seeing all three numbers lets you compare material cost, truck load size, and on‑site waste. Remember that the bag result is a minimum; ordering a few extra avoids shortfalls. The tool works in seconds, so you can adjust dimensions and instantly see how the numbers change, making budgeting and ordering a breeze. You can also switch between feet and meters if you prefer metric, but the core calculation stays the same. The result is ready to copy into a purchase order or share with your crew.

Pro tips

  • Add a 5‑10% waste allowance to the bag total.
  • Always round up to the next whole bag to avoid shortages.
  • Order extra bags for spillage and uneven subgrade.
  • Convert thickness from inches to feet before entering the value.

Real-life examples

  • A homeowner pouring a 4‑in slab for a new driveway.
  • A contractor estimating material for a 6‑in garage floor.
  • A landscaper preparing a concrete patio foundation.

Case study

John needed a 12 × 12 ft patio at 4 in depth. Using the calculator he saw he required 1.3 yd³ and 56 bags, so he ordered 60 bags. The job finished on schedule with no extra trips, saving him time and $200 in waste.

Frequently asked questions

How do I convert thickness in inches to feet?
Divide the inch value by 12; for example, 4 in ÷ 12 = 0.33 ft.
Why does the calculator show both cubic yards and cubic feet?
Contractors quote in yards, while bag calculations use cubic feet, so both help with ordering and pricing.
What if I use a different bag size?
The result shows bags for an 80‑lb bag (0.6 ft³). Adjust the count by the yield of your bag size.
Should I round up the bag count or down?
Always round up; you can’t order a fraction of a bag.
How much extra concrete should I order for waste?
Add 5‑10% extra bags to cover spillage, uneven subgrade, and minor miscalculations.