Rebar Calculator

Enter your slab or footing dimensions and rebar spacing to see how many bars and 20 ft sticks you need, total weight, and a cost comparison across rebar sizes.

Rebar Calculator

Slab Length (ft)

Slab Width (ft)

Rebar Spacing (in)

Overhang per End (in)

Pricing per 20 ft Stick (edit to match local rates)

#3 Stick ($)

#4 Stick ($)

#5 Stick ($)

#6 Stick ($)

Rebar Layout

#4 Bars Needed

42 bars

21 lengthwise + 21 widthwise

20 ft Sticks to Buy

84 sticks

1680 total linear ft

Total Weight

1122.2 lbs

0.668 lb/ft

#4 Cost

$840.00

$10.00 per stick

Purchase Option	Quantity	Est. Cost
#3 RebarBest value	84 sticks (1680 lin ft, 631.7 lbs)	$546.00
#4 Rebar	84 sticks (1680 lin ft, 1122.2 lbs)	$840.00
#5 Rebar	84 sticks (1680 lin ft, 1752.2 lbs)	$1,176.00
#6 Rebar	84 sticks (1680 lin ft, 2523.4 lbs)	$1,512.00

Cheapest option: #3 Rebar at $546.00Smaller rebar sizes (#3, #4) are cheaper per stick and adequate for most residential slabs at standard spacing. Larger sizes (#5, #6) are common in structural footings, grade beams, and commercial work where engineering specs require them.

Lap splices are required for this slabOne or both slab dimensions exceed the standard 20 ft bar length, so bars will need to be overlapped (lap-spliced). Standard lap splice length is 30 times the bar diameter (15.0 inches for #4 rebar). The stick count above already accounts for this overlap.

This is a material estimate only. Actual rebar requirements depend on structural engineering specifications, local building codes, and site conditions. Always consult your plans and local supplier for exact quantities.