The Rebar and Concrete in a Slab calculator computes the total length and weight of rebar and the volume of concrete needed for a slab.
INSTRUCTIONS: Choose units and enter the following:
- (L) Length of the slab
- (W) Width of the slab
- (D) Depth of slab
- (rS) Rebar Size (2,3,4,5,6,7,8,9,10,11,12,14,16,18,20)
- Use Size "0" for No Rebar
- (oC) On-center spacing Rebar
- (i) Inset distance from edge of slab
- (M) Number of mats
- (RL) Length of the pre-cut rebar sticks
- (LF) Lapping Factor. 40 (default) and 60 are common.
Rebar and Concrete in a Slab: The calculator returns:
- Total Length of rebar in feet.
- Total Weight of rebar in pounds.
- Estimated Rebar Cost in U.S. dollars
- Total Volume of concrete in cubic yards. Note: this accounts for the concrete displaced by rebar.
- Total Weight of Slab in pounds. Note: this includes the weight of rebar and concrete, and takes into consideration the concrete displaced by rebar.
However, the above can be automatically converted to compatible units via the pulldown menu.
The Math / Science
The rebar algorithm calculates the length of rebar in the grid based on the slab dimensions, spacing, inset, number of mats, rebar size and lapping factor. Based on the rebar length and size, the weight of rebar is computed. Based on the slab dimensions and the volume displaced by rebar, the volume of concrete is computed.
Rebar Usage
Reinforcement bars are often used in concrete including common slabs. This formula provides a length and weigh calculation that is useful in understanding the additional load of the slab added by the rebar steel. It is also useful for calculating the weight of rebar when considering transport. Steel is dense and heavy. Most vehicles would be considerably overloaded in weight of rebar long before their potential volume is full, which poses a significant safety issue. In the U.S., most pickup trucks are rated at a half or three quarters ton load rating. This rating indicates the safe weight of a load that can be carried. The rebar weight formula can help determine how many trips are required to transport the load of reinforcement steel safely.
This is useful for:
- The determination of bar length in concrete slab
- The weight of rebar in concrete slab
When the dimensions of your slab or wall exceed the length of a single piece of rebar, it is required to lap bars and tie them to create the added length. There are a few considerations. First, the length of the lap is often specified as 40 times the diameter of the rebar. In this case, 40 is lapping factor. 60 is also a common factor, but the engineering specifications should always be applied. See these YouTube videos to better understand rebar lap:
Second, the typical length of pre-cut rebar is 20', 40' and 60' in the United States.
The Pole Barn Calculator contains functions to compute the construction materials for a pole barn with concrete piers, a slab, wood framing, roof trusses for a normal gabled roof and metal panels and trim for the roof and siding.
- Gable Roof Metal: This estimates the materials needed for a metal roof for a simple gabled roof based on the roof dimensions.
- Purlins for a Roof: This computes the total number and length of purlins for a simple gable roof based on the ridge length of the roof, the roof pitch and the span of the roof.
- Trusses Needed for Roof: This computes the number of trusses needed for a roof based on the ridge length and spacing.
- Metal Siding for Gable Ends: This computes the metal siding materials (vertical panels) for a wall under a gable roof end based on the dimensions.
- Metal Siding for Gable End with Door: This computes the metal siding materials for a wall under a gable roof end based on the dimensions.
- Girts for a Building: This computes the number of rows of girts and their lengths for a building.
- Wall Beams for a Building: This computes the lengths beams for the outer wall of a building.
- Posts for a Building: This computes the number of vertical posts for a building based on dimensions and spacing.
- Rebar and Concrete in a Slab: This computes the total length and weight of rebar and the volume of concrete needed for a slab.
- Piers for a Building: This computes the number of piers for a building and the amount of concrete needed.
- Pole Barn Materials: This computes the top to bottom framing and roofing materials needed for a pole barn (see picture) based on a few dimension.
- Pole Barn Metal Roof and Siding Cost: This uses an estimated the linear feet of metal panels needed for a pole barn with a door way, and provides an estimated cost for the metal panels for the roof and siding based on a the dimension and cost per linear foot of panels.
- Corrugated Metal Paint or Coating Volume: This estimates the volume of paint or other coating (e.g., spray insulation) is needed for a corrugated surface.
IMPORTANT NOTE: Confirm all calculations with authoritative sources such as architectural drawings before risking health or wealth on the results of any calculator, and ALWAYS adhere to government approved building codes.
See Also