Rebar Weight Calculator — ASTM A615 Bar Sizes #3-#18
Calculate total rebar weight in pounds and tons by bar size, length, and quantity, with an optional cost estimate. Nominal weights per foot follow ASTM A615 Table 1 and are identical across Grade 40, 60, and 75 steel.
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Rebar Weight Chart
US Standard Rebar Sizes (#2–#18) with weight per foot, diameter, and cross-sectional area.
View Chart →ASTM A615 Rebar Weight Lookup Table
Find your bar size below for nominal diameter, cross-sectional area, and weight per foot. These are the exact values used in the calculator above. For grid layouts, pair this with the rebar grid calculator.
| Bar Size | Diameter (in) | Diameter (mm) | Area (in²) | Weight (lb/ft) | Soft Metric Equiv. |
|---|---|---|---|---|---|
| #3 | 0.375 | 9.5 | 0.11 | 0.376 | 10M |
| #4 | 0.500 | 12.7 | 0.20 | 0.668 | 13M |
| #5 | 0.625 | 15.9 | 0.31 | 1.043 | 16M |
| #6 | 0.750 | 19.1 | 0.44 | 1.502 | 19M |
| #7 | 0.875 | 22.2 | 0.60 | 2.044 | 22M |
| #8 | 1.000 | 25.4 | 0.79 | 2.670 | 25M |
| #9 | 1.128 | 28.7 | 1.00 | 3.400 | 29M |
| #10 | 1.270 | 32.3 | 1.27 | 4.303 | 32M |
| #11 | 1.410 | 35.8 | 1.56 | 5.313 | 36M |
| #14 | 1.693 | 43.0 | 2.25 | 7.650 | 43M |
| #18 | 2.257 | 57.3 | 4.00 | 13.600 | 57M |
Source: ASTM A615/A615M Standard Specification for Deformed and Plain Carbon-Steel Bars for Concrete Reinforcement, Table 1. Nominal weights, identical across Grade 40, 60, and 75.
Why Rebar Weight Matters for Ordering
Rebar is priced and delivered by weight, not by piece count, since mills and suppliers quote per ton based on current steel prices. Knowing total weight before ordering avoids both under-ordering, which stalls a pour, and over-ordering, which ties up budget in unused steel.
The bar number itself encodes the size: for bars #3 through #8, the number is the diameter in eighths of an inch, so a #6 bar is 6/8 inch, or 3/4 inch, across. Weight per foot follows directly from that diameter, since weight is proportional to cross-sectional area (area = pi x r squared) times the density of steel, roughly 0.2833 lb per cubic inch.
Grade (40, 60, or 75) refers only to yield strength and does not change weight. A #5 Grade 60 bar weighs the same 1.043 lb/ft as a #5 Grade 40 bar, per ASTM A615 Table 1. See the concrete PSI guide for how bar grade interacts with concrete strength selection.
Example Scenario: Footing Rebar Order
A contractor needs to order rebar for a continuous footing requiring two #5 bars running the perimeter of a 120 ft foundation, plus #4 stirrups.
#5 Perimeter Bars
| Bar size | #5 (1.043 lb/ft) |
| Length per bar | 120 ft |
| Quantity | 2 bars (top and bottom of footing) |
| Weight per bar | 120 x 1.043 = 125.16 lb |
#4 Stirrups
| Bar size | #4 (0.668 lb/ft) |
| Length per stirrup | 4 ft (perimeter loop) |
| Quantity | 60 stirrups |
| Weight per stirrup | 4 x 0.668 = 2.672 lb |
Combined total: 250.32 + 160.32 = 410.64 lb, or 0.21 tons. Adding a 7% lap and waste allowance brings the order weight to roughly 439.4 lb. At $0.68/lb, estimated material cost is about $298.79.
Rebar Weight Calculation Mistakes to Avoid
A #8 bar does not weigh 8 lb/ft. The number is the diameter in eighths of an inch (1 inch for #8), and weight per foot (2.670 lb/ft) comes from squaring that diameter, per ASTM A615 Table 1.
Bars longer than standard stock lengths need lap splices per ACI 318-19 Chapter 25, which adds linear footage beyond the theoretical run length. Skipping this undercounts total weight needed.
Soft metric sizes (10M-57M) are renamed imperial bars with the same physical dimensions, not new sizes. Ordering "20M" instead of the equivalent #6 can cause confusion with US-based suppliers.
Since mills price by ton, estimating cost per linear foot without converting to weight first can produce inaccurate budget figures, especially for larger bar sizes where weight per foot is high.
Bent bars such as stirrups need extra length at each bend per ACI detailing standards. Calculating stirrup weight using only the straight perimeter dimension understates actual bar length and weight.
Ordering, Delivery, and Pricing Notes
Most suppliers sell rebar in stock lengths of 20 ft, 40 ft, or 60 ft, and cut-to-length orders often carry a fabrication surcharge. Confirm available stock lengths before finalizing quantity, since ordering non-standard lengths can change total weight and cost.
Steel pricing fluctuates with scrap steel and mill output, so the price per pound entered in this calculator should reflect a current supplier quote rather than a fixed historical number. Delivery fees for full truckloads of rebar are typically negotiated separately from material cost.
Frequently Asked Questions
Per ASTM A615 nominal weights, #3 rebar weighs 0.376 lb/ft, #4 weighs 0.668 lb/ft, #5 weighs 1.043 lb/ft, #6 weighs 1.502 lb/ft, #7 weighs 2.044 lb/ft, and #8 weighs 2.670 lb/ft. Larger sizes up to #18 weigh as much as 13.60 lb/ft.
The imperial formula is Weight (lb/ft) = N² / 533.4, where N is the bar size number representing diameter in eighths of an inch. The metric equivalent is Weight (kg/m) = D² / 162, where D is the bar diameter in millimeters.
Divide the total weight in pounds by 2,000 to get short tons, the standard US unit for mill and supplier pricing. Most rebar suppliers price and deliver by the ton for orders above a few hundred bars.
For US customary bar sizes #3 through #8, the number represents the bar diameter in eighths of an inch. A #4 bar is 4/8 inch, or 0.5 inch, in diameter. Sizes #9, #10, #11, #14, and #18 use rounded numbers rather than exact eighths, per ASTM A615 Table 1.
No. Grade refers to yield strength, not weight. A #5 Grade 60 bar and a #5 Grade 40 bar have the same nominal diameter and the same weight per foot per ASTM A615, since weight is a function of cross-sectional area, not strength.
Most estimators add 5-10% to account for cut offs, laps, and bends, though this is a fabrication and estimating practice rather than a fixed code requirement. Projects with heavy lap splicing per ACI 318-19 Chapter 25 may need a higher allowance.
Rebar is typically quoted per ton or per hundredweight (cwt) based on current steel mill pricing, which fluctuates with scrap steel and rebar futures markets. Small retail quantities are sometimes priced per linear foot instead.
Sources & Methodology
- ASTM A615/A615M-24, Standard Specification for Deformed and Plain Carbon-Steel Bars for Concrete Reinforcement, Table 1: Nominal Dimensions and Weights. astm.org
- ASTM A706/A706M, Standard Specification for Low-Alloy Steel Deformed and Plain Bars for Concrete Reinforcement (weldable grades, same nominal dimensions as A615). astm.org
- ACI 318-19, Chapter 25: Reinforcement Details, Sections 25.5 (splices). American Concrete Institute. concrete.org
- Concrete Reinforcing Steel Institute (CRSI), Manual of Standard Practice, 30th Edition, rebar size and soft metric conversion tables. crsi.org
Last reviewed: July 2026. Reviewed by site author.
⚠ Engineering Disclaimer
This calculator provides estimates for planning purposes. For permitted structural work, foundations, multi-story construction, retaining walls over 4 feet, and commercial projects, calculations must be verified by a licensed structural engineer per IBC 2024 §1604. ConcreteCalculate.com is not liable for structural decisions made from these estimates.
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