Rebar Calculator
#8 Reinforcing Bar
ASTM A615 (US customary) reinforcing bar — diameter 25.4 mm (1.000 in), cross-sectional area, mass per metre, and standard spacing options.
Diameter
25.4 mm
Area
0.785 in²
Perimeter
3.14 in
Mass per metre
2.67 lb/ft
Area per foot width at common spacings
For slab or wall reinforcement specified as “#8@ spacing c/c” — the area provided per unit width at each standard centre-to-centre spacing.
| Spacing | As (in²/ft) |
|---|---|
| #8 @ 4in c/c | 2.356 |
| #8 @ 6in c/c | 1.571 |
| #8 @ 8in c/c | 1.178 |
| #8 @ 9in c/c | 1.047 |
| #8 @ 10in c/c | 0.942 |
| #8 @ 12in c/c | 0.785 |
| #8 @ 16in c/c | 0.589 |
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 #8.
| Bar | As (in²/ft) |
|---|---|
| #3 | 0.221 |
| #4 | 0.393 |
| #5 | 0.614 |
| #6 | 0.884 |
| #7 | 1.203 |
| #8 (this bar) | 1.571 |
| #9 | 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 #8 in the Rebar Calculator →