Concrete reinforcement reference
Rebar Size Chart
Select a U.S. rebar size to view its nominal diameter, cross-sectional area, perimeter, and linear weight. Search, compare, sort, and find the first listed bar meeting a required steel area.
- Basis
- ASTM A615/A615M
- Sizes
- #3 through #18
- Units
- U.S. and metric
- Use
- Nominal property lookup
Selected bar reference
Interactive Rebar Size and Dimension Chart
Choose a bar size and unit display. The diagram and property summary update from the selected table row.
- Selected size
- #4
- Nominal diameter
- 0.500 in · 12.7 mm
- Nominal area
- 0.20 in² · 129 mm²
- Nominal perimeter
- 1.571 in · 39.9 mm
- Linear weight
- 0.668 lb/ft · 0.994 kg/m
- Comparison
- —
Reference only: nominal size and weight do not determine required reinforcement. Use the governing code, project drawings, specifications, and qualified engineering review.
Standard U.S. designations
U.S. Rebar Sizes, Dimensions, Areas, and Weights
The table is server-rendered so the complete reference remains readable without JavaScript.
Search by designation or value. Select up to five rows for the comparison chart. Column sorting preserves the verified natural size order on reset.
No rebar sizes match the current search and property settings.
| Compare | Nominal diameter | Cross-sectional area | Nominal perimeter | Linear weight | Copy | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| #3 | 0.375 | 9.5 | 0.11 | 71 | 1.178 | 29.9 | 0.376 | 0.560 | ||
| #4 | 0.500 | 12.7 | 0.20 | 129 | 1.571 | 39.9 | 0.668 | 0.994 | ||
| #5 | 0.625 | 15.9 | 0.31 | 199 | 1.963 | 49.9 | 1.043 | 1.552 | ||
| #6 | 0.750 | 19.1 | 0.44 | 284 | 2.356 | 59.8 | 1.502 | 2.235 | ||
| #7 | 0.875 | 22.2 | 0.60 | 387 | 2.749 | 69.8 | 2.044 | 3.042 | ||
| #8 | 1.000 | 25.4 | 0.79 | 510 | 3.142 | 79.8 | 2.670 | 3.973 | ||
| #9 | 1.128 | 28.7 | 1.00 | 645 | 3.544 | 90.0 | 3.400 | 5.060 | ||
| #10 | 1.270 | 32.3 | 1.27 | 819 | 3.990 | 101.3 | 4.303 | 6.404 | ||
| #11 | 1.410 | 35.8 | 1.56 | 1006 | 4.430 | 112.5 | 5.313 | 7.907 | ||
| #14 | 1.693 | 43.0 | 2.25 | 1452 | 5.319 | 135.1 | 7.650 | 11.384 | ||
| #18 | 2.257 | 57.3 | 4.00 | 2581 | 7.090 | 180.1 | 13.600 | 20.239 | ||
Values are nominal reference properties. The table does not include grade, yield strength, deformation geometry, hook dimensions, development length, lap length, concrete cover, spacing, or structural capacity.
Area lookup and table actions
Selected-size comparison
Compare Rebar Diameter, Area, or Weight
Select up to five table rows, then compare one physical property in a compatible unit system.
Select one or more rebar sizes in the table to compare them.
How to Read This Rebar Size Chart
- Bar number: #3 through #8 approximately correspond to nominal diameter in eighths of an inch. Larger designations use standardized nominal dimensions and should be read from the table.
- Area: cross-sectional area is the key geometric property used when comparing provided reinforcing-steel area.
- Weight: multiply nominal weight per unit length by total bar length for an estimating check.
- Nominal means reference geometry: a deformed bar is not a smooth cylinder, so field measurements across ribs can differ.
Important Engineering Limitations
This chart does not select reinforcement or verify a reinforced-concrete design. Required bar size and spacing depend on factored loads, member geometry, concrete strength, steel grade, cover, spacing limits, crack control, development length, lap splices, seismic detailing, exposure, and the adopted code.
Do not substitute a different U.S. or metric designation solely because the nominal diameter appears close. Confirm area, grade, material specification, detailing, availability, and approval requirements.
Rebar Dimensions, Area, and Weight Relationships
Nominal properties are based on the equivalent plain-round section associated with the bar’s nominal weight per unit length. The two most useful geometry checks are:
Use this as a reasonableness check against the listed nominal area, allowing for published rounding.
Keep the units consistent: lb/ft with feet, or kg/m with meters.
- Nominal diameter
- Equivalent round-bar diameter used to define the standard size.
- Nominal area
- Equivalent cross-sectional steel area for the designation.
- Nominal perimeter
- Equivalent circular perimeter, not a measurement around the ribs.
- Linear weight
- Reference weight or mass for one unit of bar length.
Why #9, #10, and larger bars need a table
The familiar “bar number divided by eight” shortcut works for #3 through #8. It should not be extended to #9, #10, #11, #14, or #18. For example, #10 is a standardized designation with a nominal diameter of 1.270 inches—not 10/8 inches.
U.S. and SI values
ASTM A615 and A615M state that inch-pound and SI values are separate standard systems and may not be exact equivalents. This page displays both for convenient reference, but a compliance calculation should stay within the governing unit system.
Rebar Size Chart Examples
Look up a #5 bar
Given: #5 rebar.
Lookup: 0.625 in nominal diameter, 0.31 in² nominal area, and 1.043 lb/ft nominal weight.
Interpretation: the size chart identifies geometry and weight only; it does not establish that #5 is adequate for a member.
Estimate the weight of twenty 20-ft #4 bars
Total length: 20 bars × 20 ft = 400 ft.
Estimated weight: 400 ft × 0.668 lb/ft = 267.2 lb.
Sanity check: actual purchase and shipping weights can vary with tolerances, coatings, fabrication, and supplier practices.
Find the first bar meeting 0.75 in²
Enter 0.75 in² in the area lookup. The first listed bar with equal or greater nominal area is #8 at 0.79 in².
Limitation: this is not a design selection because number of bars, spacing, cover, development, and strength checks remain unresolved.
What the Chart Can—and Cannot—Tell You
Use the chart for
- Diameter and area lookup
- Weight and mass estimating
- Comparing standard designations
- Checking drawing schedules and takeoffs
- Finding the first listed bar meeting a stated geometric area
Use design documents and code checks for
- Required reinforcing area
- Bar count and spacing
- Minimum and maximum reinforcement
- Cover, development, hooks, and lap splices
- Grade, weldability, seismic detailing, and exposure
Common mistakes to avoid
- Using rib-to-rib diameter as the nominal diameter
- Applying the eighth-inch shortcut above #8
- Mixing SI and inch-pound standard values
- Assuming equal diameter means an approved substitution
- Treating a size lookup as structural approval
Sources, Standard Basis, and Dataset Scope
Conventional U.S. bar designations #3, #4, #5, #6, #7, #8, #9, #10, #11, #14, and #18; nominal dimensions and linear weights.
The controlling basis is ASTM A615/A615M-26. The official standard identifies its size-and-dimension table as the source of standard bar designations and states that the nominal dimensions of a deformed bar correspond to an equivalent plain round bar with the same nominal weight per unit length.
- ASTM A615/A615M-26Controls standard carbon-steel reinforcing-bar designations, nominal properties, grades, scope, and unit-system requirements.
- CRSI Ready ReferenceConfirms the industry lookup need for standard rebar sizes, diameters, areas, weights, hooks, and marking information.
Dataset and Review Details
- Publisher
- Turn2Engineering
- Standard basis
- ASTM A615/A615M-26
- Standard status checked
- August 3, 2026
- Property type
- Nominal reference values
- Unit treatment
- U.S. and SI shown separately
- Known exclusions
- Grade capacity, detailing, hooks, development, splices, cover, and spacing
- Rights status
- Limited educational reference; CSV disabled pending redistribution review
- Page purpose
- Engineering lookup and estimating support
Related Reinforcement Resources
Rebar Size Chart FAQs
Conventional U.S. reinforcing-bar designations commonly run from #3 through #18, with the standard series shown here as #3, #4, #5, #6, #7, #8, #9, #10, #11, #14, and #18.
#4 rebar has a nominal diameter of 0.500 inch. That nominal value describes the equivalent plain-round section; a caliper measurement across deformations may differ.
The bar-number-in-eighths shortcut applies to #3 through #8. Larger designations use standard nominal dimensions, so #10 is listed at 1.270 inches rather than 1.250 inches.
Multiply the table’s nominal weight per unit length by the total length, using lb/ft with feet or kg/m with meters.
A nearest-size comparison is informational only. Any substitution must address area, grade, material specification, detailing, availability, governing documents, and required approval.
Rebar Size Chart Summary
Use the interactive diagram and table to identify nominal rebar diameter, area, perimeter, and linear weight. Use the area matcher and comparison chart for reference checks, then move to the project’s structural drawings, specifications, and governing design requirements before selecting reinforcement.
- Estimate rebar quantity, total length, weight, and cost
The calculator extends this size reference into a project takeoff workflow without selecting structural reinforcement.