Steel Rebar Calculator — Weight, Cost & Bar Schedule
🔩 Rebar weight = Length × Weight/ft × Quantity. #4 (0.668 lbs/ft): 20 ft bar = 13.36 lbs. #5 (1.043): 20 ft = 20.86 lbs. #6 (1.502): 20 ft = 30.04 lbs. 10% waste factor standard for laps. Enter bar size below for exact weight and cost — free, no signup.
Bar number ÷ 8 = nominal diameter in inches (#4 = 0.5")
Standard stock lengths: 20 ft and 40 ft
10% waste factor standard for laps and cuts
2026 US pricing: $0.60-$1.20/lb ($700-$1,200/ton)
ℹ️ This free steel rebar calculator uses ASTM A615 standard weights. Enter bar size, length and quantity to get exact weight, linear feet and cost. Updated November 2026.
💡 Planning Tip: Add 10% waste for standard laps. For complex layouts or heavy splicing, use 15%. Always order in full stock lengths (20 ft or 40 ft) to minimize cutting waste.
📊 ASTM A615 Standard Rebar Sizes & Weights
Bar Size
Nominal Diameter
Weight (lbs/ft)
Weight (20 ft bar)
Common Use
#3
0.375"
0.376
7.52 lbs
Stirrups, ties, light slabs
#4
0.500"
0.668
13.36 lbs
Residential slabs, footings
#5
0.625"
1.043
20.86 lbs
Beams, heavier slabs
#6
0.750"
1.502
30.04 lbs
Columns, heavy beams
#8
1.000"
2.670
53.40 lbs
Heavy structural, commercial
#10
1.270"
4.303
86.06 lbs
Large foundations, bridges
📊 Rebar Weight Quick Reference (Common Lengths)
Total weight for common bar lengths and quantities:
Bar Size
10 ft Bar
20 ft Bar
40 ft Bar
10× 20 ft Bars
#3
3.76 lbs
7.52 lbs
15.04 lbs
75.2 lbs
#4
6.68 lbs
13.36 lbs
26.72 lbs
133.6 lbs
#5
10.43 lbs
20.86 lbs
41.72 lbs
208.6 lbs
#6
15.02 lbs
30.04 lbs
60.08 lbs
300.4 lbs
#8
26.70 lbs
53.40 lbs
106.8 lbs
534.0 lbs
👨 Mike — Residential Slab, Texas
Project: 20 ft × 20 ft slab | #4 @ 12" OC | 2 directions
✅ "Perfect for budgeting. The 10% waste factor was spot on for our laps."
How Do I Calculate Rebar Weight? (Quick Answer)
Formula: Total Weight (lbs) = Length (ft) × Weight per foot (lbs/ft) × Quantity × Waste Factor
Examples at 20 ft:
#3 rebar: 20 × 0.376 = 7.52 lbs per bar
#4 rebar: 20 × 0.668 = 13.36 lbs per bar
#5 rebar: 20 × 1.043 = 20.86 lbs per bar
#6 rebar: 20 × 1.502 = 30.04 lbs per bar
#8 rebar: 20 × 2.670 = 53.40 lbs per bar
Multiply by quantity and waste factor (1.10 for 10%) for total project weight.
What is a Steel Rebar Calculator and How Does It Work?
A steel rebar calculator determines the total weight, linear footage and cost of reinforcing bars for concrete projects. Our steel rebar calculator uses ASTM A615 standard weights to provide accurate estimates for slabs, beams, columns and footings. The calculator answers: How much does my rebar weigh? How many bars do I need? What will it cost?
How does the calculator work? Select your bar size (#3 through #10), enter the length of each bar and the quantity, choose your project type, add a waste factor for laps, and enter the price per pound. The calculator instantly shows total weight, total linear feet, weight per bar, cost per bar and total cost.
How to Calculate Rebar for a Slab
For a rectangular slab with rebar in both directions:
Bars running width: (Length ÷ Spacing) + 1. Multiply by slab width for linear feet.
Bars running length: (Width ÷ Spacing) + 1. Multiply by slab length for linear feet.
Example: 20 ft × 20 ft slab with #4 @ 12" OC:
Bars running width: (20 × 12 ÷ 12) + 1 = 21 bars × 20 ft = 420 ft
Bars running length: 21 bars × 20 ft = 420 ft
Total: 840 linear feet → 840 × 0.668 = 561 lbs (before waste).
2026 US Rebar Pricing
Retail / small quantities: $0.85-$1.20 per lb (20 ft sticks at home centers).
Bulk / contractor pricing: $700-$1,200 per ton ($0.35-$0.60 per lb) depending on region and quantity.
Regional variations: Northeast and West higher, South and Midwest lower. Grade 60 is standard; Grade 75/80 costs more.
Rebar Grade and Specification
ASTM A615 is the standard specification for deformed and plain carbon-steel bars for concrete reinforcement. Grade 60 (60,000 psi yield) is the most common in US construction. Grade 40 is used for light residential, Grade 75/80 for heavy structural. Always verify the grade required by your structural drawings.
❓ Frequently Asked Questions
How do I calculate rebar weight?
Rebar weight (lbs) = Length (ft) × Weight per foot (lbs/ft) × Quantity. For example, #4 rebar weighs 0.668 lbs/ft. A 20 ft #4 bar weighs 13.36 lbs. Use the calculator above for exact results.
What are the standard US rebar sizes?
ASTM A615 standard sizes: #3 (0.376 lbs/ft), #4 (0.668 lbs/ft), #5 (1.043 lbs/ft), #6 (1.502 lbs/ft), #8 (2.670 lbs/ft), #10 (4.303 lbs/ft). The bar number divided by 8 equals the nominal diameter in inches (#4 = 4/8 = 0.5 inch).
How many pieces of rebar do I need for a slab?
Divide slab width by rebar spacing and add 1. Example: 10 ft wide slab at 12-inch spacing = (10 × 12 ÷ 12) + 1 = 11 bars. Multiply by length for total linear feet. Use the calculator above for exact quantities.
How much does rebar cost?
US rebar prices in 2026 range from $0.60-$1.20 per lb depending on bar size, grade and region. A 20 ft #4 bar costs approximately $8-$16. Bulk pricing (tons) ranges $700-$1,200 per ton.
What is the difference between #4 and #5 rebar?
#4 rebar has a 0.5 inch diameter and weighs 0.668 lbs/ft. #5 rebar has a 0.625 inch diameter and weighs 1.043 lbs/ft. #5 is 56% heavier and used for heavier structural loads.
How do I calculate rebar for a rectangular footing?
Calculate bars in both directions: (Length ÷ Spacing) + 1 for bars running the width, and (Width ÷ Spacing) + 1 for bars running the length. Multiply each by the corresponding dimension to get linear feet.
How much does a 20 ft #4 rebar weigh?
A 20 ft #4 rebar weighs 13.36 lbs (20 × 0.668 = 13.36). Ten 20 ft #4 bars weigh 133.6 lbs. Use the calculator above to get exact weights for any size, length and quantity.
How much does a 20 ft #5 rebar weigh?
A 20 ft #5 rebar weighs 20.86 lbs (20 × 1.043 = 20.86). Ten 20 ft #5 bars weigh 208.6 lbs. #5 is 56% heavier than #4.
What is the weight per foot of #3 rebar?
#3 rebar weighs 0.376 lbs/ft. A 20 ft #3 bar weighs 7.52 lbs. #3 is used for stirrups, ties and light slabs.
What is the weight per foot of #6 rebar?
#6 rebar weighs 1.502 lbs/ft. A 20 ft #6 bar weighs 30.04 lbs. #6 is used for columns and heavy beams.
What is a good waste factor for rebar?
10% is standard for most projects. Use 5% for simple layouts with minimal laps. Use 15% for complex layouts with heavy splicing or many cuts.
How many bars in a ton of rebar?
Depends on bar size and length. A ton (2,000 lbs) of 20 ft #4 bars contains 150 bars (2000 ÷ 13.36). Of 20 ft #5 bars contains 96 bars (2000 ÷ 20.86). Use the calculator above with your specific bar size.
💡 Expert Tips for Rebar Planning
Tip #1: Always add 10% waste for standard laps and cuts. For complex layouts or heavy splicing, use 15%.
Tip #2: Order in full stock lengths (20 ft or 40 ft) to minimize cutting waste. Custom-cut lengths cost more.
Tip #3: Verify rebar grade (40, 60, 75, 80) with your structural drawings. Grade 60 is standard for most US residential and commercial work.
Tip #4: Don't forget tie wire, chairs and bar supports — these are separate from rebar cost but essential for proper placement.
Tip #5: For slabs, ensure rebar has adequate concrete cover (typically 2-3 inches for earth contact).
Tip #6: Bulk pricing (tons) saves 30-50% vs retail per-pound for projects over 500 lbs.
🔩 Still Asking "How Much Rebar Do I Need?"
Enter bar size and quantity. Get exact weight and cost in 30 seconds. Free, no signup.
🛡️ CDCalculators proprietary steel rebar calculator — data sources: ASTM A615, CRSI Manual of Standard Practice, 2026 US market pricing. Last updated November 12, 2026. Disclaimer: Estimates only. Verify with structural drawings and local building codes.