REFERENCE TABLE · CONSTRUCTION · REBAR
Every US rebar size from #3 to #18 with the official ASTM A615 / CRSI numbers: nominal diameter, cross-sectional area, and weight per foot. Pick a bar below and the calculator pulls its full spec sheet plus metric equivalents — a #4 bar (1/2″, 0.20 in², 0.668 lb/ft) cut to 20 feet weighs 13.36 lb (6.06 kg). The full printable chart is under the calculator.
Pick a bar number and enter the total length in feet. The calculator returns the bar’s official specs — nominal diameter in inches and millimeters, cross-sectional area, weight per foot, and soft-metric size — plus the total weight in pounds and kilograms. Values come straight from the published ASTM A615 / CRSI standard table.
Number = eighths of an inch; weight = published, not guessed. Up to #8, the bar number is the nominal diameter in eighths of an inch — #3 is 3/8″ (0.375 in), #8 is 1″. Sizes #9 through #18 are area-based legacy sizes (#9 is 1.128 in, not 9/8 in). Every diameter, area, and weight-per-foot on this page is the ASTM A615 / CRSI published standard value — 0.668 lb/ft for #4, 2.670 lb/ft for #8, 13.600 lb/ft for #18. Default check: #4 × 20 ft = 0.668 × 20 = 13.36 lb (6.06 kg). Use the printed chart for ordering, the calculator for takeoffs — and always build to your engineer’s or local code’s spec, not to this chart alone.
Setup: a #4 bar (1/2″ nominal, 0.20 in² area, 0.668 lb/ft) and 20 feet of it.
Line 1 — the weight per foot. #4 rebar weighs 0.668 lb/ft per the ASTM A615 table — a published constant, not something you measure. Its metric twin is the #13 soft-metric bar (12.7 mm diameter).
Line 2 — the total. 0.668 lb/ft × 20 ft = 13.36 lb. In kilograms: 13.36 × 0.4536 = 6.06 kg.
Line 3 — the takeoff. Need four 20-ft sticks for a footing run? 13.36 × 4 = 53.44 lb — run the length field at 80 ft and the calculator says the same thing.
Branch — heavier steel (#8 × 40 ft): 2.670 lb/ft × 40 ft = 106.80 lb (48.44 kg). Specs: 1 in diameter (25.4 mm), 0.79 in² area, soft metric #25 — typical for parking structures and industrial slabs.
Branch — the big end (#11 × 100 ft): 5.313 lb/ft × 100 ft = 531.30 lb (240.99 kg). 1.410 in diameter, 1.56 in² area — load-bearing structures, and the largest size routinely bent on site.
| Bar | Diameter (in) | Diameter (mm) | Area (in²) | Weight (lb/ft) | Soft metric | Common uses |
|---|---|---|---|---|---|---|
| #3 | 0.375 (3/8) | 9.525 | 0.11 | 0.376 | #10 | Driveways, sidewalks, patios, light slabs — crack control |
| #4 | 0.500 (1/2) | 12.7 | 0.20 | 0.668 | #13 | Footings, foundation walls, residential slabs and columns — the workhorse |
| #5 | 0.625 (5/8) | 15.875 | 0.31 | 1.043 | #16 | Foundations, grade beams, retaining walls |
| #6 | 0.750 (3/4) | 19.05 | 0.44 | 1.502 | #19 | Columns, heavy residential, basement walls |
| #7 | 0.875 (7/8) | 22.225 | 0.60 | 2.044 | #22 | Elevated slabs, commercial foundations |
| #8 | 1.000 (1) | 25.4 | 0.79 | 2.670 | #25 | Parking structures, industrial buildings |
| #9 | 1.128 (1 1/8) | 28.65 | 1.00 | 3.400 | #29 | Large columns, shear walls |
| #10 | 1.270 (1 1/4) | 32.26 | 1.27 | 4.303 | #32 | Commercial beams, columns, structural supports |
| #11 | 1.410 (1 3/8) | 35.81 | 1.56 | 5.313 | #36 | Load-bearing structures — largest routinely bent on site |
| #14 | 1.693 (1 3/4) | 43.00 | 2.25 | 7.650 | #43 | Dams, bridges, docks, heavy civil work |
| #18 | 2.257 (2 1/4) | 57.3 | 4.00 | 13.600 | #57 | Mega-projects — rarely bent on site |
| Output | Formula | What it means |
|---|---|---|
| Total weight (lb) | weight per foot × length | 13.36 lb at the defaults — the number your supplier bills by. |
| Total weight (kg) | lb × 0.4536 | 6.06 kg at the defaults — for metric takeoffs and freight estimates. |
| Nominal diameter | from the standard table | 0.500 in (12.7 mm) for #4 — measured on the bar body, not the deformations. |
| Cross-sectional area | from the standard table | 0.20 in² for #4 — the number structural math (steel area per foot of slab) starts from. |
| Soft-metric size | standard cross-reference | #13 for a #4 bar — the same steel, named by its metric diameter. |
All diameters, areas, and weights are the ASTM A615 / CRSI published nominal values — nominal means measured on the bar body excluding deformations, so a caliper on the ribs reads slightly larger. Real bars vary within mill tolerances; the weights are nominal and your supplier’s scale rules the invoice. This page covers standard deformed carbon-steel bars #3–#18 only — it does not cover epoxy-coated, stainless, or metric-only sizes, and it does not size reinforcement for your project. Bar selection is engineering work: always build to your structural engineer’s drawings and your local building code.
Bright Side Kit. "US Rebar Size Chart: #3–#18 Specs & Weight Calculator." https://brightoolbox.com/rebar-size-chart/ Accessed October 24, 2026.Data sourcesFor sizes #3 through #8, the number is the nominal diameter in eighths of an inch: #4 is 4/8 = 1/2 inch (0.500 in). Sizes #9, #10, #11, #14, and #18 are area-based legacy sizes — #9 is 1.128 in, not 9/8 in — which is why the chart above matters.
For a typical 4-inch residential driveway or patio slab, #3 (3/8″) on an 18-inch grid is the common choice, mainly for crack control. Thicker slabs and heavier vehicle traffic usually step up to #4. This is convention, not a prescription — check your local building code or engineer before you pour.
#4 (1/2″) is the standard for most residential footings and foundation walls; #5 (5/8″) shows up in larger homes, retaining walls, and grade beams. Footing steel is the part an inspector looks at first — build to the stamped drawings.
Yes — every diameter, area, and weight on this page is the ASTM A615 / CRSI published nominal value (e.g. #4: 0.500 in, 0.20 in², 0.668 lb/ft). Nominal means measured on the bar body excluding the deformations, so the ribs read a touch larger on a caliper.
The same bars, named by approximate metric diameter: a #4 US bar is a #13 metric bar (12.7 mm), a #8 is a #25 (25.4 mm). They are identical steel — two naming systems, one product — which matters when drawings and suppliers speak different units.
20.86 lb: 1.043 lb/ft × 20 ft. Suppliers usually sell 20-ft and 40-ft lengths; the calculator’s length field handles any total — enter 20 for one stick, 80 for four.