Reinforcing bars · Size & tolerance table

Metric rebar sizes and mass per metre

Standard: BS 4449 · ISO 6935-2 · EN 10080

The nominal mass of a reinforcing bar is that of a round bar of the nominal diameter at a density of 7,850 kg/m³ — about d²/162 kg/m. Bars per tonne are worked out from the nominal mass; real bundles vary within the tolerance.

Nominal sizes

Diameter mm	Area mm²	Mass kg/m	Length per tonne m/t	12 m bars per tonne pcs/t	Mass tolerance %
6	28.3	0.222	4504.5	375.4	± 6.0
8	50.3	0.395	2531.6	211.0	± 6.0
10	78.5	0.617	1620.7	135.1	± 4.5
12	113	0.888	1126.1	93.8	± 4.5
14	154	1.21	826.4	68.9	± 4.5
16	201	1.58	632.9	52.7	± 4.5
18	254	2	500.0	41.7	± 4.5
20	314	2.47	404.9	33.7	± 4.5
22	380	2.98	335.6	28.0	± 4.5
25	491	3.85	259.7	21.6	± 4.5
28	616	4.83	207.0	17.3	± 4.5
32	804	6.31	158.5	13.2	± 4.5
36	1018	7.99	125.2	10.4	± 4.5
40	1257	9.87	101.3	8.4	± 4.5
50	1963	15.4	64.9	5.4	± 4.5

6, 18, 22, 36 and 50 mm are not stocked by every mill.
Mass tolerances are those of BS 4449; ISO 6935-2 and ASTM A615 set their own.