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🔩 Rebar Reference

Rebar sizes, weights, grades, and specifications.

Rebar Size Chart​

Standard Sizes (Imperial)​

Bar SizeDiameter (in)Area (sq in)Weight (lb/ft)
#30.375 (3/8")0.110.376
#40.500 (1/2")0.200.668
#50.625 (5/8")0.311.043
#60.750 (3/4")0.441.502
#70.875 (7/8")0.602.044
#81.000 (1")0.792.670
#91.128 (1-1/8")1.003.400
#101.270 (1-1/4")1.274.303
#111.410 (1-3/8")1.565.313
#141.693 (1-3/4")2.257.650
#182.257 (2-1/4")4.0013.60
Size Naming

Bar numbers (#3, #4, etc.) represent the diameter in eighths of an inch.

  • #3 = 3/8"
  • #4 = 4/8" = 1/2"
  • #5 = 5/8"

Metric Rebar Sizes​

Metric SizeDiameter (mm)Area (mm²)Weight (kg/m)Imperial Equiv
10M11.31000.785~#3
15M16.02001.570~#5
20M19.53002.355~#6
25M25.25003.925~#8
30M29.97005.495~#9
35M35.710007.850~#11
45M43.7150011.775~#14
55M56.4250019.625~#18

Rebar Grades​

Standard Grades (ASTM A615)​

GradeYield StrengthUse
Grade 4040,000 psiLight duty, non-structural
Grade 6060,000 psiMost common, general construction
Grade 7575,000 psiHigh-strength applications
Grade 8080,000 psiSeismic, high-load applications

Identification Marks​

Rebar has rolled-in marks showing:

  1. Mill symbol - Manufacturer
  2. Bar size - Number
  3. Steel type - S = Carbon, W = Low-alloy, A = Axle
  4. Grade - One line = 60, Two lines = 75

Standard Lengths​

TypeLength
Standard stock20 ft
Also available30 ft, 40 ft, 60 ft
CoilsContinuous (for spirals)

Coverage Requirements​

Minimum Concrete Cover (Typical)​

LocationCover
Concrete against earth3"
Concrete exposed to weather (#6 or larger)2"
Concrete exposed to weather (#5 or smaller)1-1/2"
Not exposed to weather (slabs, walls)3/4" to 1-1/2"
Columns, beams1-1/2"
Footings3"

Spacing Requirements​

Minimum Clear Spacing​

ConditionMinimum
Between parallel bars1" or bar diameter (larger)
Between layers1"
Bundled barsMust fit aggregate

Maximum Spacing (Typical)​

ElementMaximum
Slab bars18" or 3× slab thickness
Wall bars18"
Temperature steel5× slab thickness or 18"

Lap Splice Lengths​

Class B Splices (Most Common)​

Bar SizeGrade 60 (Normal Concrete)
#312"
#415"
#519"
#623"
#727"
#830"
#939"
#1049"
#1160"

Actual splice length depends on concrete strength and bar location

Development Length​

Minimum length bar must extend into concrete for full strength.

Bottom Bars (Grade 60, 3000 psi concrete)​

Bar SizeDevelopment Length
#312"
#412"
#515"
#618"
#721"
#824"
#930"
#1038"
#1147"

Top bars require 1.3× these lengths

Bend Requirements​

Standard Hook Dimensions​

Bar Size90° Hook (Extension)180° Hook (Extension)Min Bend Diameter
#36"4"2-1/4"
#48"5"3"
#510"6"3-3/4"
#612"7"4-1/2"
#714"8"5-1/4"
#816"9"6"
#919"11"9"
#1022"13"10-1/8"
#1124"14"11-1/4"

Estimating Quantities​

Weight per 100 LF​

Bar SizeWeight (lbs)
#337.6
#466.8
#5104.3
#6150.2
#7204.4
#8267.0
#9340.0
#10430.3
#11531.3

Quick Estimating​

Slab on grade (typical):

  • Light duty: 0.5-1.0 lb/SF
  • Normal: 1.0-1.5 lb/SF
  • Heavy duty: 1.5-2.5 lb/SF

Footings (typical):

  • 2-4 lb/SF of footing area

Walls:

  • 1-2 lb/SF of wall area

Welded Wire Reinforcement (WWR)​

Common Styles​

StyleWire SizeSpacingWeight (lb/100 SF)
6×6-W1.4×W1.4Light6"×6"21
6×6-W2.1×W2.1Medium6"×6"30
6×6-W2.9×W2.9Heavy6"×6"42
4×4-W1.4×W1.4Light4"×4"31
4×4-W2.1×W2.1Medium4"×4"44
4×4-W2.9×W2.9Heavy4"×4"62

Style format: Spacing × Spacing - Wire Size × Wire Size

Epoxy-Coated Rebar​

When Required​

  • Parking structures
  • Bridge decks
  • Marine environments
  • Corrosive conditions

Handling Notes​

  • Don't drag on ground
  • Repair damaged coating
  • Use coated tie wire
  • Extra development length required

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