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Rebar Size Chart 2026: Complete #2 to #18 Diameter, Area & Grade Reference

July 28, 2026
0 11 12 minutes read
Rebar Size Chart Complete #2 to #18 Diameter, Area & Grade Reference
Rebar Size Chart
Rebar Size Chart – Complete #2 to #18 Diameter, Area & Grade Reference | ConcreteCalculate.com
ASTM A615 & ACI 318 Reference

Rebar Size Chart
Complete #2 to #18 Diameter, Area & Grade Reference

The most complete rebar size reference for contractors, engineers, and estimators — diameter, area, weight, grades, spacing, cover, and lap splice in one place.

All Sizes #2–#18 Imperial & Metric Grades 40–100 Worked Examples 📅 Last Updated: July 2026
Muhammad Ramzan Babar Reviewed by Muhammad Ramzan Babar, PhD Researcher (Plasma Physics) & Calculator Developer — View Profile

⭐ Master Rebar Size Chart – #2 to #18

Complete diameter, area, weight, and imperial/metric reference for all US standard rebar sizes.

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How to Read This Chart

The bar number equals the diameter in eighths of an inch. So #4 = 4/8 = ½ inch. Need exact material quantities? Use our Rebar Calculator.

Bar SizeSoft MetricDiameter (in)Diameter (mm)Area (in²)Weight (lb/ft)Weight (kg/m)
#2#60.2506.350.050.1670.249
#3#100.3759.5250.110.3760.561
#4#130.50012.700.200.6680.996
#5#160.62515.8750.311.0431.556
#6#190.75019.050.441.5022.240
#7#220.87522.2250.602.0443.049
#8#251.00025.400.792.6703.982
#9#291.12828.651.003.4005.071
#10#321.27032.261.274.3036.418
#11#361.41035.811.565.3137.924
#14#431.69343.002.257.65011.410
#18#572.25757.304.0013.60020.284

★ Highlighted rows (#3–#5) are most common in residential construction. Source: ASTM A615 Standard Specification for Deformed and Plain Carbon-Steel Bars.

Rebar Diameter Chart

Nominal diameter in inches and millimeters for each standard bar size.

Nominal SizeDiameter (in)Diameter (mm)
#20.2506.35
#30.3759.53
#40.50012.70
#50.62515.88
#60.75019.05
#70.87522.23
#81.00025.40
#91.12828.65
#101.27032.26
#111.41035.81
#141.69343.00
#182.25757.30

Rebar Cross-Sectional Area Chart

Cross-sectional area in square inches and square millimeters — used for reinforcement ratio calculations.

Bar SizeArea (in²)Area (mm²)
#30.1171
#40.20129
#50.31200
#60.44284
#70.60387
#80.79509
#91.00645
#101.27819
#111.561,006
#142.251,452
#184.002,581

Rebar Weight Chart

Weight per foot and per meter for each bar size. For 20 ft/40 ft bar totals and bundle weights, see our dedicated Rebar Weight Chart.

Bar SizeWeight/Ft (lb)Weight/m (kg)
#30.3760.561
#40.6680.996
#51.0431.556
#61.5022.240
#82.6703.982
#104.3036.418

Rebar Dimensions Chart

Diameter, circumference, radius, and cross-sectional area combined for quick geometric reference.

Bar SizeDiameter (in)Radius (in)Circumference (in)Area (in²)
#30.3750.18751.1780.11
#40.5000.2501.5710.20
#50.6250.31251.9630.31
#60.7500.3752.3560.44
#81.0000.5003.1420.79
#101.2700.6353.9901.27

US Rebar Size vs Metric Rebar Size Chart

Soft metric sizes are direct conversions of US imperial sizes — no physical change to the bar, only the naming.

US BarMetric EquivalentDiameter (mm)
#3#109.5
#4#1312.7
#5#1615.9
#6#1919.1
#7#2222.2
#8#2525.4
#9#2928.7
#10#3232.3
#11#3635.8
#14#4343.0
#18#5757.3

Rebar Grade Comparison Chart

Yield strength, tensile strength, and typical applications for each ASTM A615/A706 grade.

GradeYield Strength (psi)Tensile Strength (psi)Common Applications
Grade 4040,00060,000Light residential, older codes, stirrups
Grade 6060,00090,000US construction standard — slabs, footings, columns
Grade 7575,000100,000Heavy structural, coils, higher-load applications
Grade 8080,000105,000High-rise, seismic zones, weldable (A706)
Grade 100100,000115,000 (min ratio 1.15×)High-strength structural, reduced bar congestion

Source: ASTM A615/A615M (Grades 40, 60, 75, 100) and ASTM A706 (Grade 60, 80 — weldable low-alloy steel).

Standard Rebar Length Chart

Common stock lengths available from US suppliers.

LengthTypical AvailabilityCommon Use
20 ftStandard stock lengthMost residential and commercial work
30 ftSpecial order (select suppliers)Larger spans, reduced splicing
40 ftStandard stock lengthCommercial, large slabs, reduced waste
60 ftSpecial order / mill directLong-span bridge and industrial work
CustomCut-to-length servicePrecast, prefabricated cages, tight tolerances

⭐ Rebar Size by Construction Application

Quick-reference table matching bar size to common structural elements.

ApplicationRecommended Bar Size
Footings#4–#5
Slabs#3–#4
Driveways#3–#4
Sidewalks#3
Retaining Walls#4–#6
Beams#5–#8
Columns#6–#11
Bridge Decks#5–#8
High-Rise Buildings#8–#18

Rebar Spacing Guide

Typical center-to-center spacing for common applications — always confirm against structural drawings.

ApplicationTypical Spacing (in)
Slabs12–18
Footings12–16
Walls12–16
Foundations12–18
Driveways12–18

Plan exact spacing with our Rebar Spacing Calculator.

Rebar Cover Requirements Chart

Minimum concrete cover recommendations per ACI 318 exposure category.

Exposure ConditionMinimum Cover
Interior (slabs, walls)3/4 in
Exterior (exposed to weather)1.5–2 in
Cast Against Soil3 in
Marine Environments3 in (often more with epoxy coating)

Per ACI 318 Chapter 20. Always verify against project-specific structural drawings and local building codes.

Rebar Development & Lap Splice Size Chart

Quick reference for Grade 60 Class B tension lap splice lengths at common concrete strengths.

Bar SizeLap Splice @ 3,000 PSILap Splice @ 4,000 PSILap Splice @ 5,000 PSI
#322″19″17″
#429″25″23″
#536″31″28″
#643″37″34″
#763″54″49″
#872″62″56″
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Need More Detail?

Class B lap splice = 1.3 × development length (ACI 318 25.5.2), Grade 60, uncoated, normal-weight, “other than top” bars. For top bars, epoxy coating, or other grades, see our dedicated Rebar Lap Splice Chart for full modification factors.

Rebar Bending Radius Chart

Minimum inside bend diameter per ACI 318 for main reinforcing bars (without hooks).

Bar SizeACI 318 RuleMin. Bend Diameter (approx)
#3–#86 × db1.5″–6″
#9–#118 × db9″–11.3″
#1410 × db16.9″
#1810 × db22.6″

Stirrups/ties use a smaller 4×db minimum. Values shown are for main bars bent without hooks, per ACI 318.

⭐ Visual Rebar Size Comparison Chart

Relative diameter comparison across all standard bar sizes, at a glance.

#3
0.375″
#4
0.500″
#5
0.625″
#6
0.750″
#8
1.000″
#10
1.270″
#14
1.693″
#18
2.257″
Rebar Size Chart showing #2 to #18 bars at true relative scale

Common Residential Rebar Sizes

Most frequently specified bar sizes for home construction projects.

ApplicationCommon Bar Size
Patios#3
Sidewalks#3
Driveways#3–#4
Garage Floors#3–#4
Foundations#4–#5
Pool Decks#3–#4

Common Commercial Rebar Sizes

Typical bar sizes used in commercial and industrial structures.

ApplicationCommon Bar Size
Warehouses#4–#6
Bridges#5–#8
High-Rise Buildings#8–#18
Industrial Slabs#4–#6
Parking Structures#5–#7

Rebar Size Selection Guide

Decision table for choosing the right bar size for your project.

ProjectRecommended Bar SizeReason
Backyard patio#3Light foot traffic, minimal load
Standard driveway#4Balances cost with vehicle load capacity
House footing#4–#5Supports foundation load per soil bearing capacity
Retaining wall (under 4 ft)#4–#5Resists lateral soil pressure
Suspended slab/beam#6–#8Handles tension and bending loads
High-rise column#10–#18Maximum load capacity with reduced bar count

Contractor Worked Examples

Real-world rebar sizing decisions for common job scenarios.

1

House Footing — Selecting Bar Size

Given: Standard residential footing, 24 in wide × 12 in deep
1
Base recommendation for footings: #4–#5 rebar
2
Select #5 for continuous footings with two horizontal bars top and bottom.
Result: Use #5 rebar, 3 in clear cover from soil contact per ACI 318.
2

Driveway Slab — Bar Size and Spacing

Given: 4 in thick residential driveway, standard car traffic
1
Recommended bar size: #4
2
Recommended spacing: 18 in on center, grid pattern
Result: #4 rebar at 18 in O.C. grid, 1.5 in cover from top surface.
3

Retaining Wall — Vertical Reinforcement

Given: 3.5 ft tall retaining wall, moderate soil pressure
1
Base recommendation: #4–#5 vertical bars
2
Select #5 at 12 in O.C. for added lateral resistance.
Result: #5 rebar vertical, 12 in O.C., with #4 horizontal bars at 16 in O.C.
4

Suspended Slab — Beam Reinforcement

Given: 20 ft span suspended slab with supporting beams
1
Beam main reinforcement: #7 rebar
2
Lap splice at 4,000 PSI concrete: 54 in (from lap splice chart)
Result: #7 rebar with 54 in Class B lap splices at all beam continuations.
5

Column Reinforcement — High-Rise

Given: Ground-floor column, high-rise building, heavy axial load
1
Base recommendation: #10–#18 main bars
2
Select #14 Grade 80 for reduced bar congestion at high load.
Result: #14 Grade 80 rebar, minimum bend diameter 16.9 in for any required bends.

Frequently Asked Questions

What is #4 rebar?
#4 rebar has a nominal diameter of 1/2 inch (12.7 mm), weighing 0.668 lb per foot. It’s the most common size for residential slabs, driveways, and foundations.
What size rebar should I use for a driveway?
#3 or #4 rebar is standard for residential driveways, with #4 being the industry default for 4-6 inch thick slabs spaced 12-18 inches on center.
Is #5 stronger than #4?
Yes, #5 has a larger diameter and greater cross-sectional area (0.31 in² vs 0.20 in²), giving it higher load-bearing capacity per bar at the same grade.
What is the most common residential rebar size?
#3 and #4 are most common, used for driveways, sidewalks, patios, and foundation footings, with #4 as the default for slab-on-grade work.
How do I measure rebar size?
The rebar number equals the diameter in eighths of an inch. Measure diameter with calipers and multiply by 8 — a 0.5 inch bar is #4.
Can I substitute one bar size for another?
Only with engineering approval, matching total steel cross-sectional area and adjusting spacing to maintain the same reinforcement ratio.
What rebar size is used for footings?
Residential footings typically use #4 or #5; larger commercial footings may require #6 or #7 based on engineering calculations.
What is the difference between Grade 40 and Grade 60 rebar?
Grade 60 has a minimum yield strength of 60,000 PSI vs Grade 40’s 40,000 PSI. Grade 60 is now the US construction standard.
What size rebar is used for a slab foundation?
Residential slab foundations typically use #3 or #4 rebar in a grid, spaced 12-18 inches on center depending on thickness and soil conditions.
What is the minimum bend diameter for rebar?
Per ACI 318, minimum inside bend diameter is 6× bar diameter for #3-#8, 8× for #9-#11, and 10× for #14 and #18.
How much concrete cover does rebar need?
Per ACI 318: 3/4 inch for interior slabs, 1.5-2 inches for exterior exposed concrete, and 3 inches for concrete cast against soil or marine environments.
What is rebar development length?
Development length is the minimum embedment needed for a bar to transfer its full tensile force to concrete without slipping, calculated per ACI 318.
How long is a standard rebar stick?
Standard US rebar comes in 20 ft and 40 ft lengths, with 30 ft and 60 ft also available, plus custom cut lengths from most suppliers.
What size rebar is used in bridge decks?
Bridge decks typically use #5 to #8 rebar, often epoxy-coated, with exact size determined by DOT structural specifications.
What rebar size is used for columns?
Columns typically use #6 to #11 for main vertical reinforcement, with larger bars (#10-#18) used in high-rise structures.

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July 28, 2026
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