Rebar Calculator
#9 Reinforcing Bar
ASTM A615 (US customary) reinforcing bar — diameter 28.7 mm (1.128 in), cross-sectional area, mass per metre, and standard spacing options.
Diameter
28.7 mm
Area
0.999 in²
Perimeter
3.54 in
Mass per metre
3.40 lb/ft
Area per foot width at common spacings
For slab or wall reinforcement specified as “#9@ spacing c/c” — the area provided per unit width at each standard centre-to-centre spacing.
| Spacing | As (in²/ft) |
|---|---|
| #9 @ 4in c/c | 2.998 |
| #9 @ 6in c/c | 1.999 |
| #9 @ 8in c/c | 1.499 |
| #9 @ 9in c/c | 1.332 |
| #9 @ 10in c/c | 1.199 |
| #9 @ 12in c/c | 0.999 |
| #9 @ 16in c/c | 0.749 |
Equivalent options at 6in spacing
Every US bar size at the same reference spacing, so you can see at a glance which other size lands near the same area per unit width as #9.
| Bar | As (in²/ft) |
|---|---|
| #3 | 0.221 |
| #4 | 0.393 |
| #5 | 0.614 |
| #6 | 0.884 |
| #7 | 1.203 |
| #8 | 1.571 |
| #9 (this bar) | 1.999 |
| #10 | 2.534 |
| #11 | 3.123 |
| #14 | 4.502 |
| #18 | 8.002 |
Area and mass are computed directly from the nominal diameter (mass assumes standard steel density, 7850 kg/m³) — the same values the Rebar Calculator uses.
Open #9 in the Rebar Calculator →