#8 Rebar (1 Inch Reinforcing 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 | #8 | Code Standard | ASTM A615 / A706 |
| Nominal Diameter (db) | 1 in | Metric Diameter | 25.4 mm |
| Cross-Sectional Area (Ab) | 0.79 in² | Metric Area | 510 mm² |
| Linear Weight | 2.67 lb/ft | Metric Mass | 3.973 kg/m |
| Nominal Perimeter | 3.142 in | Metric Perimeter | 79.8 mm |
| Minimum Clear Spacing | max(1.0″, 1″) | ACI Provision | ACI 318-19 §25.2.1 |
| Hook Type | Min. Inside Bend Pin | Extension Length (US) | Extension Length (SI) |
|---|---|---|---|
| 90° Standard Hook | 6″ (152 mm) | 12″ (12db) | 305 mm |
| 180° Standard Hook | 6″ (152 mm) | 4″ (max(4db, 2.5″)) | 102 mm |
Common Structural Applications
- ›The industry standard 1-inch diameter heavy bar for commercial framing
- ›Primary flexure in parking structures, highway bridges, and multi-story frames
- ›Tension reinforcement in deep transfer girders and cantilever bents
- ›Foundation mat reinforcement and pile caps
Exactly 1.000 inch diameter. Bend pin diameter is 6 inches. Tension development length exceeds 38 inches in 4000 psi concrete for bottom bars and 49 inches for top bars.
#8 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. |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 3.160in²/ft | 2.370in²/ft | 1.896in²/ft | 1.580in²/ft | 1.354in²/ft | 1.185in²/ft | 1.053in²/ft | 0.948in²/ft | 0.790in²/ft | 0.677in²/ft | 0.593in²/ft | 0.527in²/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 | 54.8″(1392 mm) | 71.2″(1808 mm) | ACI 318-19 Table 25.4.2.3 | ld ≥ 12″ (300 mm) |
| 4,000 psi | 47.4″(1204 mm) | 61.7″(1567 mm) | ACI 318-19 Table 25.4.2.3 | ld ≥ 12″ (300 mm) |
| 5,000 psi | 42.4″(1077 mm) | 55.2″(1402 mm) | ACI 318-19 Table 25.4.2.3 | ld ≥ 12″ (300 mm) |
| 6,000 psi | 38.7″(983 mm) | 50.3″(1278 mm) | ACI 318-19 Table 25.4.2.3 | ld ≥ 12″ (300 mm) |
Design Reinforcement with #8 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.