basic

Cement Bag Calculator

Number of 80-lb concrete bags for a slab.

Estimate the number of 80-lb (or 60-lb / 40-lb) ready-mix concrete bags needed to pour a slab of length × width × thickness, with a 10% waste allowance.

Nadia Almasri By Nadia Almasri
Published Last reviewed 1 min read

Inputs

ft
ft
in

Results

Enter values and click Calculate to see results.
Was this helpful?

How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

Volume (ft³) = L · W · (thickness_in / 12). Bags = ceil(volume × 1.10 / bag_yield_ft3).

In depth

Estimate the number of 80-lb (or 60-lb / 40-lb) ready-mix concrete bags needed to pour a slab of length × width × thickness, with a 10% waste allowance.