What is the purpose of using #4 rebar in the slab?

The #4 rebar is used to reinforce the concrete slab, providing additional tensile strength and helping to prevent cracking.

Why is soil design excluded from this calculator?

Soil design is site-specific and depends on various factors such as soil type, moisture content, and load-bearing capacity, which require professional assessment.

What thickness is recommended for a residential slab?

A thickness of 6 inches is commonly recommended for residential slabs to ensure adequate strength and durability.

What does IRC R506 cover?

IRC R506 provides guidelines for the design and construction of concrete floors on the ground, including reinforcement requirements and curing methods.

16 by 24 ft slab at 6 inches

Calculate the requirements for a residential slab measuring 16 ft by 24 ft with a thickness of 6 inches and #4 rebar at 18-inch spacing. Ensure compliance with IRC R506.

Formula SSC-2026.1

Formula SSC-2026.1 · 4,000 PSI

Order volume

9.37 yd³

7.164 m³ placed+waste

Order weight

37,950 lb

17,214 kg

80 lb bags

422

11 pallets at 42 bags

60 lb bags

563

0.45 ft³ yield each

Rebar

696.00 ft

47 × 20 ft · 49 × 6 m · 511 lb

Ready-mix vs bags

$1,546.11

Truck $1,546.11 · 80 lb bags $2,848.50

Slab footprint and rebar gridLive scaled blueprint

Grid lines are equalized so the drawing stays readable. The order count uses on-center spacing with a bar at each end of the layout, then holds concrete cover in the field.

Bill of materials and shopping list
Item	Net	Waste	Order	Unit price	Line total	Source Spec Material / Tool
Ready-mix concrete	8.52 yd³	10%	9.37 yd³ / 7.164 m³	USD	$1,546.11	Source Spec Material / Tool
Short-load fee	Full load	—	1 truck @ 10 yd³	USD	$0.00	Source Spec Material / Tool
80 lb pre-mix bags	383.3 bags	10%	422 bags	USD	$2,848.50	Source Spec Material / Tool
60 lb pre-mix bags	511.1 bags	10%	563 bags	USD	$3,040.20	Source Spec Material / Tool
#4 rebar sticks, 20 ft	47 sticks	10%	52 sticks / 49 × 6 m	USD	$728.00	Source Spec Material / Tool
Rebar chairs	187 crossings	10%	206 chairs	USD	$57.68	Source Spec Material / Tool
Tie wire rolls	187 ties	10%	1 rolls	USD	$8.00	Source Spec Material / Tool

Source links open a product search on the Amazon storefront for the selected currency. SiteSpecCalc may earn a commission. The link does not change the quantities above.

Ready-mix truck

$1,546.11

0.94 nominal 10 yd³ loads · 1 to order

80 lb bags

$2,848.50

60 lb alternative $3,040.20 · delivery weight 37,950 lb

Side-by-side thickness comparison at the same footprint
Thickness	Order yd³	Order m³	80 lb bags	Rebar ft	Ready-mix	80 lb cost
4 in	7.28	5.565	328	766	$1,201.04	$2,214.00
5 in	8.32	6.365	375	766	$1,373.57	$2,531.25
6 in	9.37	7.164	422	766	$1,546.11	$2,848.50

Show the deterministic formula

Slab ft³ = L × W × thickness ÷ 12. Thickened-edge extra = footing band × (footing depth − slab thickness), with corner squares counted once.

yd³ = ft³ ÷ 27. m³ = ft³ × 0.0283168. Weight uses 150 lb/ft³, then the header converts that pound total at 1 lb = 0.45359237 kg. 80 lb bags yield 0.6 ft³ and 60 lb bags yield 0.45 ft³. Currency changes the price labels only.

Bars across a span = floor(span ÷ spacing) + 1. Order sticks = that count, plus 10, 5, or 15 percent waste, cut from 20 ft and 6 m stock. Chairs = one per grid intersection.

Contractor sign-off

Project: 16 by 24 ft slab at 6 inches

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This sheet is an estimate for ordering and layout discussion. It is not a sealed design. Confirm the quantities with a licensed local professional and the authority having jurisdiction before you buy or build.

Engineering notes

This calculator helps you determine the specifications for a residential concrete slab measuring 16 ft by 24 ft with a thickness of 6 inches. The design incorporates #4 rebar placed at 18-inch intervals to enhance structural integrity.

Please note that soil design considerations are excluded from this calculation. For accurate results, consult local building codes and a qualified engineer.

Code reference

IRC R506 - Concrete Floors on Ground

Field questions

What is the purpose of using #4 rebar in the slab?: The #4 rebar is used to reinforce the concrete slab, providing additional tensile strength and helping to prevent cracking.
Why is soil design excluded from this calculator?: Soil design is site-specific and depends on various factors such as soil type, moisture content, and load-bearing capacity, which require professional assessment.
What thickness is recommended for a residential slab?: A thickness of 6 inches is commonly recommended for residential slabs to ensure adequate strength and durability.
What does IRC R506 cover?: IRC R506 provides guidelines for the design and construction of concrete floors on the ground, including reinforcement requirements and curing methods.