Billets & blooms · Size & tolerance table

Billet and bloom sizes and mass per metre

Standard: Mill and contract sizes (no single dimensional standard)

Billets and blooms are ordered by the side of the square (or width × thickness of a rectangle) as cast or rolled, and by length. The nominal mass is the full rectangle at 7,850 kg/m³; real sections have corner radii, which reduce the mass by less than 1% on the usual sizes.

Tolerances on side, diagonal difference (rhomboidity), straightness, twist and cut length are agreed in the contract or follow the producing mill's standard; there is no single international dimensional standard for semi-finished products.

Square billets and blooms

Section mm	A cm²	Mass kg/m	6 m piece kg	12 m piece kg	12 m pieces per tonne pcs/t
100 × 100	100	78.5	471	942	1.1
110 × 110	121	95.0	570	1140	0.9
120 × 120	144	113.0	678	1356	0.7
125 × 125	156	122.7	736	1472	0.7
130 × 130	169	132.7	796	1592	0.6
140 × 140	196	153.9	923	1846	0.5
150 × 150	225	176.6	1060	2120	0.5
160 × 160	256	201.0	1206	2412	0.4
180 × 180	324	254.3	1526	3052	0.3
200 × 200	400	314.0	1884	3768	0.3
220 × 220	484	379.9	2280	4559	0.2
250 × 250	625	490.6	2944	5888	0.2
300 × 300	900	706.5	4239	8478	0.1

Rectangular blooms (examples)

Section mm	A cm²	Mass kg/m	6 m piece kg	12 m piece kg	12 m pieces per tonne pcs/t
200 × 250	500	392.5	2355	4710	0.2
250 × 300	750	588.8	3533	7065	0.1
250 × 320	800	628.0	3768	7536	0.1
300 × 400	1200	942.0	5652	11304	0.1
360 × 450	1620	1271.7	7630	15260	0.1

Bloom sections vary from mill to mill with the caster mould sizes; these are examples, not a series.

Notes

100–150 mm square billets feed bar and rebar mills; 150–200 mm square feeds wire rod and merchant-bar mills; larger blooms feed section, rail and seamless-tube mills.
Per-tonne counts are rounded and use the nominal mass.