#9 Rebar
The bar with a secret: #9 is sized so its area is exactly one square inch, an inheritance from the square bars it replaced.
1.128 inch diameter, 1.00 in2, 3.400 lb per foot
| Nominal diameter | 1.128 in (28.7 mm) |
| Cross section area | 1.00 in2 (645 mm2) |
| Weight | 3.400 lb per foot (5.060 kg per meter) |
| Typical grade | Grade 60, 60 ksi yield |
| Soft metric name | No. 29 |
| 20 ft stock bar | about 68 lb |
| Nearest Canadian bar | 30M |
Notes for design and site
The odd diameter is deliberate: #9, #10 and #11 were dimensioned to match the areas of the old 1, 1 1/8 and 1 1/4 inch square bars, so #9 delivers exactly 1.00 in2 and steel schedules become simple multiplication. It lives in heavy columns, deep transfer girders and mat foundations.
Rough lap at 40 diameters is about 45 inches, close to four feet per splice, and a 20 ft bar weighs 68 pounds. At this scale splice strategy is a design decision rather than a field habit: couplers, staggered laps or welds get chosen on the drawings.
Related Calculators and Reference
- Development Length and Lap Splice Calculator: four foot laps deserve real numbers.
- Rebar Cutting List Calculator: schedules for heavy cages.
- #10 Rebar: the next square bar descendant.
- 30M Rebar: the Canadian counterpart.
- Unit Weight of Steel: the density behind every weight here.
- Concrete Reinforcing Steel Institute: the US industry body for reinforcing steel.