Rebar Size Chart
Look up U.S. rebar diameter, cross-sectional area, soft-metric designation, and weight for common sizes #3 through #18, plus the ASTM-listed No. 20 [64] bar.
ASTM A615/A615M quick reference
U.S. Rebar Size Chart — Diameter, Area & Weight
Need a size fast? Use the chart immediately below. Diameter, area, and unit weight are nominal reference properties; the deformations are not included in nominal diameter.
- Diameter
- 0.500 in · 12.7 mm
- Area
- 0.20 in² · 129 mm²
- Weight
- 0.668 lb/ft · 0.994 kg/m
No rebar sizes match that search.
| Soft metric | ||||
|---|---|---|---|---|
| #3 | No. 103/8 in | 0.375 in9.5 mm | 0.11 in²71 mm² | 0.376 lb/ft0.560 kg/m |
| #4 | No. 131/2 in | 0.500 in12.7 mm | 0.20 in²129 mm² | 0.668 lb/ft0.994 kg/m |
| #5 | No. 165/8 in | 0.625 in15.9 mm | 0.31 in²199 mm² | 1.043 lb/ft1.552 kg/m |
| #6 | No. 193/4 in | 0.750 in19.1 mm | 0.44 in²284 mm² | 1.502 lb/ft2.235 kg/m |
| #7 | No. 227/8 in | 0.875 in22.2 mm | 0.60 in²387 mm² | 2.044 lb/ft3.042 kg/m |
| #8 | No. 251 in | 1.000 in25.4 mm | 0.79 in²510 mm² | 2.670 lb/ft3.973 kg/m |
| #9 | No. 29standard size | 1.128 in28.7 mm | 1.00 in²645 mm² | 3.400 lb/ft5.060 kg/m |
| #10 | No. 32standard size | 1.270 in32.3 mm | 1.27 in²819 mm² | 4.303 lb/ft6.404 kg/m |
| #11 | No. 36standard size | 1.410 in35.8 mm | 1.56 in²1006 mm² | 5.313 lb/ft7.907 kg/m |
| #14 | No. 43standard size | 1.693 in43.0 mm | 2.25 in²1452 mm² | 7.650 lb/ft11.38 kg/m |
| #18 | No. 57standard size | 2.257 in57.3 mm | 4.00 in²2581 mm² | 13.600 lb/ft20.24 kg/m |
| #20 | No. 64ASTM-listed; code check | 2.500 in63.5 mm | 4.91 in²3167 mm² | 16.69 lb/ft24.84 kg/m |
No. 20 [64]: ASTM A615/A615M-26 includes No. 20 [64] as the largest bar in the specification, but notes that consensus design codes may not recognize its use. Check the governing code, authority, drawings, and detailing requirements before specifying it.
Selected-size estimator
Rebar Weight for a Given Length
Uses the nominal unit weight from the chart above.
Current bar: #4 at 0.668 lb/ft. Change the selected size in the chart above to recalculate.
This is a nominal estimating calculation: total weight = unit weight × total length. Purchase, fabrication, coating, and tolerance effects can change actual shipment weight.
What “Nominal Diameter” Means for Rebar
- Selected size
- #4 · No. 13
- Diameter
- 0.500 in · 12.7 mm
- Area
- 0.20 in² · 129 mm²
- Unit weight
- 0.668 lb/ft · 0.994 kg/m
How U.S. Rebar Numbers Work
#3 through #8
For these sizes, the bar number equals nominal diameter in eighths of an inch. #4 = 4/8 = 1/2 in; #5 = 5/8 in; #8 = 1 in.
#9 and larger
Do not continue the eighth-inch shortcut. Use the standardized table values: #9 = 1.128 in, #10 = 1.270 in, #11 = 1.410 in, and so on.
Why sizes are skipped
The conventional U.S. series is not every integer. After #11 it jumps to #14, #18, and the ASTM-listed #20 size.
Soft-Metric Rebar Is Not the Same as Canadian “M” Bar
U.S. soft-metric designations are alternate names for the same physical U.S. bars: #4 corresponds to No. 13, #5 to No. 16, and #8 to No. 25. Canadian hard-metric bars such as 10M, 15M, and 20M are a different size series and should not be treated as interchangeable just because the numbers look similar.
Quick Rebar Size and Weight Examples
What size is #4 rebar?
#4 rebar has a nominal diameter of 0.500 in (12.7 mm), nominal area of 0.20 in² (129 mm²), and nominal weight of 0.668 lb/ft (0.994 kg/m).
How much does a 20-ft #4 bar weigh?
20 ft × 0.668 lb/ft = 13.36 lb. Use the estimator above for other lengths, quantities, and selected sizes.
What size is #5 rebar?
#5 rebar is 0.625 in (5/8 in) nominal diameter, has 0.31 in² nominal area, and weighs 1.043 lb/ft.
What This Rebar Size Chart Does Not Determine
Size lookup is not reinforcement design. This page does not determine required bar size, bar count, spacing, grade, cover, development length, lap splice length, hooks, crack control, seismic detailing, or structural capacity. Use the governing code, project drawings/specifications, and qualified engineering review.
Also do not substitute a U.S. bar, soft-metric designation, or Canadian metric bar solely because nominal dimensions appear close. Confirm the governing material specification and project approval requirements.
Sources and Standard Basis
The primary basis is ASTM A615/A615M-26, active as of October 6, 2026. ASTM states that the standard sizes and dimensions of deformed bars are given in Table 1, that nominal dimensions correspond to an equivalent plain round bar of the same nominal weight per unit length, and that inch-pound and SI values are separate standard systems.
- ASTM A615/A615M-26 — Standard Specification for Deformed and Plain Carbon-Steel Bars for Concrete ReinforcementPrimary standard basis for bar designations, nominal dimensions, unit-system treatment, and the No. 20 [64] code-recognition note.
- CRSI — Bar IdentificationIndustry reference for identifying reinforcing-bar size, material type, grade markings, and U.S. bar-marking practice.
- CRSI — FAQs About BarsIndustry explanation of reinforcing-bar identification and soft conversion between inch-pound and metric naming.
- Dataset basis
- ASTM A615/A615M-26 nominal properties
- Standard status checked
- October 6, 2026
- Sizes shown
- #3, #4, #5, #6, #7, #8, #9, #10, #11, #14, #18, #20
- Primary use
- Dimension, area, and weight lookup
Rebar Size Chart FAQs
What size is #4 rebar?
#4 rebar has a nominal diameter of 0.500 in (12.7 mm), a nominal cross-sectional area of 0.20 in² (129 mm²), and a nominal unit weight of 0.668 lb/ft (0.994 kg/m).
What size is #5 rebar?
#5 rebar has a nominal diameter of 0.625 in (15.9 mm), a nominal area of 0.31 in² (199 mm²), and a nominal unit weight of 1.043 lb/ft (1.552 kg/m).
Does the rebar number equal diameter?
For #3 through #8, yes: the number corresponds to nominal diameter in eighths of an inch. Do not extend that shortcut above #8; use the standard table values for #9 and larger bars.
How do I calculate total rebar weight?
Multiply nominal unit weight by total bar length. For multiple equal bars, total length equals bar length × quantity. The estimator above performs that calculation for the selected size.
Is No. 13 rebar the same as #4?
In the U.S. soft-conversion system, No. 13 is the alternate metric designation for the same #4 bar. That is different from a Canadian 15M bar.
Is #20 rebar a standard size?
ASTM A615/A615M-26 includes No. 20 [64] as the largest bar in the specification, but ASTM cautions that consensus design codes and specifications may not recognize its use. Project-specific approval and detailing may be required.