How much does #4 rebar weigh per foot?

#4 rebar (1/2 inch diameter) weighs 0.668 pounds per foot, or approximately 2/3 of a pound. For a standard 20-foot stick, that's 13.36 pounds total. This is the most common size for residential concrete slabs, driveways, and footings.

What do the rebar numbers mean (#3, #4, #5)?

The number indicates the bar diameter in eighths of an inch. #3 = 3/8 inch diameter, #4 = 4/8 (1/2 inch), #5 = 5/8 inch, #6 = 6/8 (3/4 inch), and so on. This numbering system makes it easy to remember sizes. Larger numbers mean thicker, heavier, and stronger rebar.

How do I calculate total rebar weight for a slab?

First, calculate total linear feet of rebar needed (length × width ÷ grid spacing). For example, a 20×20 foot slab with 18-inch grid spacing needs approximately 533 linear feet of rebar. Multiply by weight per foot for your bar size. Using #4 rebar at 0.668 lbs/ft: 533 × 0.668 = 356 pounds total. Always add 5-10% for waste and overlaps.

What size rebar for a 4-inch concrete slab?

For a 4-inch residential slab (garage, driveway, patio), #3 or #4 rebar is standard, placed in a 18 to 24-inch grid pattern, positioned at mid-height (2 inches from bottom). Some codes require #4 minimum. For structural slabs or heavy loads, #5 rebar with closer spacing (12-16 inches) may be required. Always check local building codes and engineer specifications.

How is rebar sold and priced?

Rebar is typically sold by the stick (20-foot lengths for #3-#6, sometimes 40 or 60 feet for larger sizes) or by weight (price per pound or per ton). As of 2024, expect $0.50-0.80 per pound retail, depending on size and market conditions. #4 rebar sticks (20ft = 13.4 lbs) cost around $7-11 each. Buying in bulk (ton quantities) gets better pricing. Some suppliers cut to length for a fee.

🏗️ Rebar Weight Calculator

Calculate rebar weight by size and length

Rebar Size

Length (feet)

Standard stick = 20 ft

Quantity (sticks)

Number of bars

Price/lb (Optional)

Current market price

📊 Rebar Weight Chart (Per Foot)

Size	Diameter	Weight/Foot	Weight/20ft Stick	Common Uses
#3	3/8"	0.376 lbs	7.5 lbs	Patios, sidewalks
#4	1/2"	0.668 lbs	13.4 lbs	Residential slabs, driveways
#5	5/8"	1.043 lbs	20.9 lbs	Heavy slabs, beams
#6	3/4"	1.502 lbs	30.0 lbs	Columns, footings
#7	7/8"	2.044 lbs	40.9 lbs	Commercial structures
#8	1"	2.670 lbs	53.4 lbs	Large beams, grade beams

💡 From Tony Martinez, 19 years concrete contractor:

"When I'm bidding jobs, rebar weight matters for two reasons: cost and labor. A residential 30×40 garage slab needs about 800 pounds of #4 rebar at 18-inch spacing. That's $480-640 in materials depending on steel prices, and it takes two guys half a day to tie it all. Don't cheap out and go to 24-inch spacing to save money—inspectors will fail you if your plans call for 18. And always order 10% extra because you'll have overlaps at splices (minimum 12 inches), waste from cutting, and a few bent bars. Trust me, running out of rebar when you're ready to pour is a nightmare."

🎯 How to Use This Calculator

Step 1: Select your rebar size (#3 through #11). If unsure, #4 is standard for most residential work.

Step 2: Enter length in feet. Standard sticks come in 20-foot lengths.

Step 3: Enter quantity (number of bars you need).

Step 4 (Optional): Enter current price per pound to calculate total cost.

⚠️ Common Mistakes

Not accounting for overlaps: When splicing rebar, you need minimum 12-inch overlaps (40× bar diameter for tension). This adds 10-15% to your linear footage needs.

Wrong spacing calculations: 18-inch spacing doesn't mean 18 inches from edge to edge—it means center-to-center of the bars.

Forgetting about chairs: Rebar sits on plastic chairs or dobies to maintain proper height in the slab. Budget these separately.

❓ FAQ

How much does #4 rebar weigh?

0.668 pounds per foot, or 13.36 pounds for a standard 20-foot stick.

What do rebar numbers mean?

The number is the diameter in eighths of an inch. #4 = 4/8 = 1/2 inch diameter.

How do I calculate slab rebar weight?

Calculate total linear feet needed, multiply by weight per foot. Example: 500 linear feet of #4 = 500 × 0.668 = 334 pounds.

What size rebar for 4-inch slab?

#3 or #4 rebar at 18-24 inch spacing is standard. Check local building codes.