Rebar size converter
Convert reinforcing bar sizes between US bar numbers, millimeters and inches, and find their weight per length.
That's 1.06× as thick as slab rebar, while footing rebar is 1.26× thicker. A bar that thick weighs 0.9944 kg/m (0.6682 lb/ft).
What it means
How thick is that bar?
Nominal diameters (ASTM A615). Weight for steel at 7,850 kg/m³; the deformations (ribs) are included in the nominal size.
Every unit
That bar in every unit
Learn
Three things worth knowing
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Number ÷ 8 = inches
#3 is ⅜ in, #6 is ¾ in, #8 is 1 in. ×3.175 gives mm.
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Square bars
Early reinforcing used square bars; when round deformed bars replaced them, sizes #9 to #11 kept the old areas.
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#10 is not 10 mm
A US #10 bar is 1.27 in (32 mm). Metric 10 mm is closest to #3.
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Background
About rebar sizes
US reinforcing bars are numbered in eighths of an inch: #4 is 4/8 = ½ in (12.7 mm), #5 is ⅝ in. From #9 the bars are sized to match the area of the old square bars, so #9 is 1.128 in.
Metric bars are simply named by diameter: 10, 12, 16, 20, 25 mm.