#9 Rebar (1-1/8 Inch Equivalent Bar)
Authoritative dimensional properties, unit weight, cross-sectional area, spacing tables, standard hook geometries, and ACI 318-19 tension development length for structural concrete design.
| Bar Designation | #9 | Code Standard | ASTM A615 / A706 |
| Nominal Diameter (db) | 1.128 in | Metric Diameter | 28.65 mm |
| Cross-Sectional Area (Ab) | 1 in² | Metric Area | 645 mm² |
| Linear Weight | 3.4 lb/ft | Metric Mass | 5.06 kg/m |
| Nominal Perimeter | 3.544 in | Metric Perimeter | 90 mm |
| Minimum Clear Spacing | max(1.0″, 1.128″) | ACI Provision | ACI 318-19 §25.2.1 |
| Hook Type | Min. Inside Bend Pin | Extension Length (US) | Extension Length (SI) |
|---|---|---|---|
| 90° Standard Hook | 9″ (229 mm) | 13.5″ (12db) | 343 mm |
| 180° Standard Hook | 9″ (229 mm) | 4.5″ (max(4db, 2.5″)) | 114 mm |
Common Structural Applications
- ›Convenient exactly 1.00 in² cross-sectional area makes manual calculations trivial
- ›Heavy commercial building columns and seismic special moment frames
- ›Large retaining walls, bridge piers, and dam spillway structures
- ›Multi-bar bundles (2 to 4 bars per bundle) in congested girders
Inside bend pin diameter jumps from 6db to 8db (9.0 inches) per ACI 318-19 Table 25.3.2. Lap splices require significant lap lengths; mechanical couplers often specified.
#9 Rebar Spacing Table (As / Unit Width)
Area of longitudinal reinforcement provided for slabs, walls, and footing mats at given on-center spacings.
| 3″ o.c. | 4″ o.c. | 5″ o.c. | 6″ o.c. | 7″ o.c. | 8″ o.c. | 9″ o.c. | 10″ o.c. | 12″ o.c. | 14″ o.c. | 16″ o.c. | 18″ o.c. |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 4.000in²/ft | 3.000in²/ft | 2.400in²/ft | 2.000in²/ft | 1.714in²/ft | 1.500in²/ft | 1.333in²/ft | 1.200in²/ft | 1.000in²/ft | 0.857in²/ft | 0.750in²/ft | 0.667in²/ft |
ACI 318-19 Tension Development Length (ld)
Calculated using ACI 318-19 Section 25.4.2.3 simplified method for Grade 60 (420 MPa) deformed bars in normal-weight concrete with clear spacing ≥ db and clear cover ≥ db.
| Concrete Strength (f'c) | Bottom Bars (ld) [ψt = 1.0] | Top Bars (ld) [ψt = 1.3] | Governing Provision | Minimum Limit |
|---|---|---|---|---|
| 3,000 psi | 61.8″(1570 mm) | 80.3″(2040 mm) | ACI 318-19 Table 25.4.2.3 | ld ≥ 12″ (300 mm) |
| 4,000 psi | 53.5″(1359 mm) | 69.6″(1768 mm) | ACI 318-19 Table 25.4.2.3 | ld ≥ 12″ (300 mm) |
| 5,000 psi | 47.9″(1217 mm) | 62.2″(1580 mm) | ACI 318-19 Table 25.4.2.3 | ld ≥ 12″ (300 mm) |
| 6,000 psi | 43.7″(1110 mm) | 56.8″(1443 mm) | ACI 318-19 Table 25.4.2.3 | ld ≥ 12″ (300 mm) |
Design Reinforcement with #9 in AXIS
Run instant ACI 318-19 beam flexure, shear stirrup spacing, column P-M interaction, and development length checks with full KaTeX step-by-step audit logs.