40lb bags in a Slab

`nb = ( "length" * "width" * "depth" )/ (0.3 ft^3)`
`(L)"Length"`
`(W)"Width"`
`(D)"Depth"`

The 40lb bags of Concrete in a Slab calculator computes the number of 40 pound bags of concrete, length of form boards and water needed for a rectangle (square) slab based on the dimensions of the slab.  

INSTRUCTIONS: Choose units and enter the following:

  • (L) Length of the slab
  • (W) Width of the slab
  • (D) Depth of the slab

40 pound bags of Concrete (nb): The calculator returns the number of 40lb bags needed for the slab and the water required to mix it in gallons.  However, this can be automatically converted to compatible units via the pull-down menu.

The Math / Science

The volume of an 40lb bag of concrete is approximately 0.45 ft3.  This calculator computes the volume of the slab in cubic feet and then divides by the cubic feet in an 40lb bag

   `nb = (L*W*D) / (0.3 ft^3)`

where:

  • nb = number of 40lb bags
  • L = length of slab
  • W = width of slab
  • D = depth of slab


Bags of Concrete Calculators

Functions and data associated with using bags of concrete in different sizes (40lb, 60lb and 80lb) to fill concrete slabs of different shapes (rectangular, round, polygon).

CAUTION: The pricing information provided is for calculating convenience with NO implied guarantees to the accuracy of the values listed. Authoritative sources should be sought to confirm any value before risking health or wealth on the veracity of the data. Furthermore, Calc gives no guarantee that you will be able to buy products at listed prices or even if they will be available.  The data provided is purely a convenience for making estimates, so we repeat, ALWAYS use local pricing and authoritative specifications.


Bags of Concrete Calculators

Functions and data associated with using bags of concrete in different sizes (40lb, 60lb and 80lb) to fill concrete slabs of different shapes (rectangular, round, polygon).

CAUTION: The pricing information provided is for calculating convenience with NO implied guarantees to the accuracy of the values listed. Authoritative sources should be sought to confirm any value before risking health or wealth on the veracity of the data. Furthermore, Calc gives no guarantee that you will be able to buy products at listed prices or even if they will be available.  The data provided is purely a convenience for making estimates, so we repeat, ALWAYS use local pricing and authoritative specifications.