# Concrete Calculator

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The Masonry Calculator contains equations and data used in working                  Rectangular Slab                      Circular Slab   5 sided polygon (pentagon) slab  DIFFERENT SLAB SHAPES  with concrete slabs, walls and piers and footers, bricks, blocks and concrete walls. The formulas in this calculator are generally used to calculate materials needed for slabs of different shapes (e.g. rectangular, circular, or polygons), masonry walls made of poured concrete, brick or block, and columns and peers.    It also includes a calculator to compute the delivery cost of bulk concrete.  For more comprehensive rebar (reinforcement bar) calculations, see the Rebar Calculator.

The SLABS tab has the following formulas: (Click on any name)

• Cubic Yards in a Rectangle Slab -  This a volume formula.
• Square Feet of a Rectangle Slab - This is an area formula.
• Length of Rebar in a Rectangle Slab - Computes the length of rebar in a slab based on the dimensions of the slab, the spacing of the rebar, the inset, the number of mats and the lapping.
• Weight of Rebar in a Rectangle Slab - Computes the weight of rebar in a slab based on its length (above) and the size of the rebar.
• Weight of Concrete by Cubic Yards -  This computes the weight of any volume of concrete (w/o rebar).
• [Could not locate page KurtHeckman.slab – total weight estimate] - Computes the total weight of a slab including concrete and rebar.
• Rebar Weight- This computes the weight of rebar as a function of the rebar size (2-18) and any length.
• Price of Delivered Concrete (mileage, material, pumping) - Computes the delivered price of concrete as a function of the bulk rate, pumping costs and the mileage to the site.
• Cubic Yards in a Circular Slab - Computes the volume of a circular slab
• Square Feet of a Circular Slab - Computes the surface area of a circular slab.
• Perimeter of a Circular Slab by Radius - Computes the perimeter of a circular slab based on the radius (r).
• Perimeter of a Circular Slab by Area - Computes the perimeter of a circular slab based on the Area (A) of the slab.      Masonry Wall (brick, block or poured concrete)
• Cubic Yards in a Polygon Slab - Computes the volume of a polygon slab (e.g. hexagon).
• Square Feet of a Polygon Slab - Computes the surface area of a polygon (e.g. octagon) slab.
• Length of the Perimeter of a Polygon Slab - This computes the perimeter of a polygon slab (e.g. pentagon).
• Length of one Side of a Polygon Slab - This computes the appropriate length of one side of a polygon slab.

The Walls, Footers and Columns(piers) tab has the following formulas:

• Brick or Blocka in a Wall (U.S.A.) - This computes the number of standard U.S. brick or block needed for a wall using feet and inches.
• Brick or Blocks in a Wall (Europe) - This computes the number of standard European brick or block needed for a wall using meters and centimeters.
• Brick or Blocks in a Wall (custom) - This computes the number of brick or block needed for a wall with user designated (variable) block dimensions including the mortar joint.
• Square Feet of Forms for a Wall - This computes the surface area for the forms needed when pouring a concrete wall (e.g. basement foundation wall).  It lets the user choose the surface area on one side, two sides, or two sides and the edges to provide the complete surface area needed for forms.
• Cubic Yards in a Concrete Wall - This computes the volume of concrete in a concrete wall.
• Cubic Yards in a Footer - This computes the volume of concrete in a footer base on the footer depth, length and width.
• Cubic Yards in a Footer (based on cross-section area) - This computes the volume of concrete in a footer based on the footer's cross-section area.
• Cubic Yards in a Column (pier) - This computes the volume of a circular concrete pier or column.

# Other Information:

Sea sand is usually discouraged when mixing concrete.  The salt content of the sand weakens the concrete and shortens the life of the concrete structure.

### Weight of concrete:

• Cubic Feet in a 40lb bag of concrete mix (e.g. Quikrete) = 0.3 ft3
• Cubic Feet in a 60lb bag of concrete mix = 0.45 ft3
• Cubic Feet in an 80lb bag of concrete mix = 0.6 ft3
• Weight of a cubic foot of Concrete = 145 lbs/ft3
• Weight of a cubic yard of Concrete = 1.9575 tons/yd3

### Guidelines for Depth of Concrete Slabs

Always consult local building codes for the best answer.  However, a guideline for the  depth of concrete is as follows:

4” - Home basement floors, farm building floors
4”-5” - Home garage and porches
5”-6” - Sidewalks, barn and granary floors, small sheds
6”-8” - Driveways

### History

The term rebar is short for reinforcement bars, and refers to bars of steel embedded in concrete to improve tinsel strength.