🔩 Rebar Reference
Rebar sizes, weights, grades, and specifications.
Rebar Size Chart
Standard Sizes (Imperial)
| Bar Size | Diameter (in) | Area (sq in) | Weight (lb/ft) |
|---|---|---|---|
| #3 | 0.375 (3/8") | 0.11 | 0.376 |
| #4 | 0.500 (1/2") | 0.20 | 0.668 |
| #5 | 0.625 (5/8") | 0.31 | 1.043 |
| #6 | 0.750 (3/4") | 0.44 | 1.502 |
| #7 | 0.875 (7/8") | 0.60 | 2.044 |
| #8 | 1.000 (1") | 0.79 | 2.670 |
| #9 | 1.128 (1-1/8") | 1.00 | 3.400 |
| #10 | 1.270 (1-1/4") | 1.27 | 4.303 |
| #11 | 1.410 (1-3/8") | 1.56 | 5.313 |
| #14 | 1.693 (1-3/4") | 2.25 | 7.650 |
| #18 | 2.257 (2-1/4") | 4.00 | 13.60 |
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 Size | Diameter (mm) | Area (mm²) | Weight (kg/m) | Imperial Equiv |
|---|---|---|---|---|
| 10M | 11.3 | 100 | 0.785 | ~#3 |
| 15M | 16.0 | 200 | 1.570 | ~#5 |
| 20M | 19.5 | 300 | 2.355 | ~#6 |
| 25M | 25.2 | 500 | 3.925 | ~#8 |
| 30M | 29.9 | 700 | 5.495 | ~#9 |
| 35M | 35.7 | 1000 | 7.850 | ~#11 |
| 45M | 43.7 | 1500 | 11.775 | ~#14 |
| 55M | 56.4 | 2500 | 19.625 | ~#18 |
Rebar Grades
Standard Grades (ASTM A615)
| Grade | Yield Strength | Use |
|---|---|---|
| Grade 40 | 40,000 psi | Light duty, non-structural |
| Grade 60 | 60,000 psi | Most common, general construction |
| Grade 75 | 75,000 psi | High-strength applications |
| Grade 80 | 80,000 psi | Seismic, high-load applications |
Identification Marks
Rebar has rolled-in marks showing:
- Mill symbol - Manufacturer
- Bar size - Number
- Steel type - S = Carbon, W = Low-alloy, A = Axle
- Grade - One line = 60, Two lines = 75
Standard Lengths
| Type | Length |
|---|---|
| Standard stock | 20 ft |
| Also available | 30 ft, 40 ft, 60 ft |
| Coils | Continuous (for spirals) |
Coverage Requirements
Minimum Concrete Cover (Typical)
| Location | Cover |
|---|---|
| Concrete against earth | 3" |
| 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, beams | 1-1/2" |
| Footings | 3" |
Spacing Requirements
Minimum Clear Spacing
| Condition | Minimum |
|---|---|
| Between parallel bars | 1" or bar diameter (larger) |
| Between layers | 1" |
| Bundled bars | Must fit aggregate |
Maximum Spacing (Typical)
| Element | Maximum |
|---|---|
| Slab bars | 18" or 3× slab thickness |
| Wall bars | 18" |
| Temperature steel | 5× slab thickness or 18" |
Lap Splice Lengths
Class B Splices (Most Common)
| Bar Size | Grade 60 (Normal Concrete) |
|---|---|
| #3 | 12" |
| #4 | 15" |
| #5 | 19" |
| #6 | 23" |
| #7 | 27" |
| #8 | 30" |
| #9 | 39" |
| #10 | 49" |
| #11 | 60" |
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 Size | Development Length |
|---|---|
| #3 | 12" |
| #4 | 12" |
| #5 | 15" |
| #6 | 18" |
| #7 | 21" |
| #8 | 24" |
| #9 | 30" |
| #10 | 38" |
| #11 | 47" |
Top bars require 1.3× these lengths
Bend Requirements
Standard Hook Dimensions
| Bar Size | 90° Hook (Extension) | 180° Hook (Extension) | Min Bend Diameter |
|---|---|---|---|
| #3 | 6" | 4" | 2-1/4" |
| #4 | 8" | 5" | 3" |
| #5 | 10" | 6" | 3-3/4" |
| #6 | 12" | 7" | 4-1/2" |
| #7 | 14" | 8" | 5-1/4" |
| #8 | 16" | 9" | 6" |
| #9 | 19" | 11" | 9" |
| #10 | 22" | 13" | 10-1/8" |
| #11 | 24" | 14" | 11-1/4" |
Estimating Quantities
Weight per 100 LF
| Bar Size | Weight (lbs) |
|---|---|
| #3 | 37.6 |
| #4 | 66.8 |
| #5 | 104.3 |
| #6 | 150.2 |
| #7 | 204.4 |
| #8 | 267.0 |
| #9 | 340.0 |
| #10 | 430.3 |
| #11 | 531.3 |
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
| Style | Wire Size | Spacing | Weight (lb/100 SF) |
|---|---|---|---|
| 6×6-W1.4×W1.4 | Light | 6"×6" | 21 |
| 6×6-W2.1×W2.1 | Medium | 6"×6" | 30 |
| 6×6-W2.9×W2.9 | Heavy | 6"×6" | 42 |
| 4×4-W1.4×W1.4 | Light | 4"×4" | 31 |
| 4×4-W2.1×W2.1 | Medium | 4"×4" | 44 |
| 4×4-W2.9×W2.9 | Heavy | 4"×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