How do you calculate the weight of a reinforcement bar?

Weight per metre in kilograms is 0.006165 times the diameter in millimetres squared: steel at 7,850 kg/m³ times the bar's cross-section. A 12 mm bar is 0.006165 x 144 = 0.888 kg/m; a 16 mm bar is 1.578 kg/m; a 25 mm bar is 3.853 kg/m. Multiply by the length as fixed, including laps, to get the weight for the bill.

How many bars are there in a tonne?

For standard 12 m bars: about 94 bars of 12 mm, 53 of 16 mm, 34 of 20 mm, 22 of 25 mm and 13 of 32 mm. The table gives the exact figures; a bundle is priced by weight, so this is mainly for checking deliveries.

What does BRC A8 weigh per square metre?

3.95 kg/m²: 8 mm wires at 200 mm centres both ways, ten wires per metre in each direction. A7 is 3.02 kg/m², A9 4.99 kg/m² and A10 6.16 kg/m². Add the laps (usually 200 mm to 300 mm, or as the drawings say) and cutting waste when converting a slab area to tonnes ordered.

How is reinforcement measured in a bill of quantities?

Bar reinforcement by weight, as fixed, with the length taken from the bar-bending schedule or measured from the drawings including the laps shown; rolling margin, tying wire, spacers and chairs are deemed included in the rate. Mesh is measured by area, as fixed, with laps deemed included unless the bill says otherwise. On-screen take-off software such as Take-Off by WEQS gives the lengths and areas; the weight comes from these tables.

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Rebar weight and BRC mesh weight tables

The weight of steel reinforcement per metre and per square metre, for turning a take-off of lengths and areas into the kilograms and tonnes a bill of quantities is priced in.

STEEL AT 7,850 kg/m³ · MALAYSIAN BRC SIZES WITH BS 4483 REFERENCES · UPDATED SEPTEMBER 2026

Bar weights are calculated, not quoted: 0.006165 x d² kilograms per metre, with d the nominal diameter in millimetres. That is the density of steel times the nominal cross-section, and it is the figure every bar-bending schedule and every supplier's invoice uses. Actual bars are rolled to a tolerance, and the difference between the nominal and the actual weight (the rolling margin) is the supplier's and the contractor's business, not the bill's.

Bars Bars at spacing BRC A-series BRC B-series Questions

Weight of reinforcement bars

Weight of high-tensile and mild steel bars by nominal diameter
Diameter	kg per metre	kg per 12 m bar	12 m bars per tonne	Area, mm²
6 mm	0.222	2.66	375	28.3
8 mm	0.395	4.73	211	50.3
10 mm	0.617	7.40	135	78.5
12 mm	0.888	10.65	94	113.1
16 mm	1.578	18.94	53	201.1
20 mm	2.466	29.59	34	314.2
25 mm	3.853	46.24	22	490.9
32 mm	6.313	75.76	13	804.2
40 mm	9.864	118.37	8	1256.6

Bars at spacing: area and weight per metre width

For slabs and walls: the steel area in mm² per metre width, and the weight in kg per square metre, for bars at the spacing shown in one direction. Two-way slabs add the two directions.

Area (mm²/m) / weight (kg/m²) of bars at centres in one direction
Diameter	at 100 mm	at 150 mm	at 200 mm	at 250 mm	at 300 mm
6 mm	283 / 2.22	188 / 1.48	141 / 1.11	113 / 0.89	94 / 0.74
8 mm	503 / 3.95	335 / 2.63	251 / 1.97	201 / 1.58	168 / 1.32
10 mm	785 / 6.17	524 / 4.11	393 / 3.08	314 / 2.47	262 / 2.06
12 mm	1,131 / 8.88	754 / 5.92	565 / 4.44	452 / 3.55	377 / 2.96
16 mm	2,011 / 15.78	1,340 / 10.52	1,005 / 7.89	804 / 6.31	670 / 5.26
20 mm	3,142 / 24.66	2,094 / 16.44	1,571 / 12.33	1,257 / 9.86	1,047 / 8.22
25 mm	4,909 / 38.53	3,272 / 25.69	2,454 / 19.27	1,963 / 15.41	1,636 / 12.84
32 mm	8,042 / 63.13	5,362 / 42.09	4,021 / 31.56	3,217 / 25.25	2,681 / 21.04
40 mm	12,566 / 98.64	8,378 / 65.76	6,283 / 49.32	5,027 / 39.46	4,189 / 32.88

BRC mesh, A-series (square mesh)

Square mesh with the same wire and 200 mm pitch both ways, the fabric used in ground slabs, aprons and drains. Malaysian suppliers name the mesh by the wire size; the BS 4483 reference gives the steel area in mm² per metre.

BRC A-series fabric: wire size, steel area and weight
Mesh	Wires	Area each way, mm²/m	kg/m²	BS 4483
A5	5 mm at 200 mm both ways	98	1.54	A98
A6	6 mm at 200 mm both ways	141	2.22	A142
A7	7 mm at 200 mm both ways	192	3.02	A193
A8	8 mm at 200 mm both ways	251	3.95	A252
A9	9 mm at 200 mm both ways	318	4.99	–
A10	10 mm at 200 mm both ways	393	6.17	A393

BRC mesh, B-series (structural mesh)

Rectangular mesh with heavier main wires at 100 mm pitch and lighter cross wires at 200 mm, used where the slab spans one way.

BRC B-series fabric: wire sizes, steel area and weight
Mesh	Wires	Area main / cross, mm²/m	kg/m²	BS 4483
B6	6 mm at 100 mm main, 7 mm at 200 mm cross	283 / 192	3.73	B283
B7	7 mm at 100 mm main, 7 mm at 200 mm cross	385 / 192	4.53	B385
B8	8 mm at 100 mm main, 8 mm at 200 mm cross	503 / 251	5.92	B503
B10	10 mm at 100 mm main, 8 mm at 200 mm cross	785 / 251	8.14	B785
B12	12 mm at 100 mm main, 8 mm at 200 mm cross	1131 / 251	10.85	B1131

Questions we get asked

How do you calculate the weight of a reinforcement bar?: Weight per metre in kilograms is 0.006165 times the diameter in millimetres squared: steel at 7,850 kg/m³ times the bar's cross-section. A 12 mm bar is 0.006165 x 144 = 0.888 kg/m; a 16 mm bar is 1.578 kg/m; a 25 mm bar is 3.853 kg/m. Multiply by the length as fixed, including laps, to get the weight for the bill.
How many bars are there in a tonne?: For standard 12 m bars: about 94 bars of 12 mm, 53 of 16 mm, 34 of 20 mm, 22 of 25 mm and 13 of 32 mm. The table gives the exact figures; a bundle is priced by weight, so this is mainly for checking deliveries.
What does BRC A8 weigh per square metre?: 3.95 kg/m²: 8 mm wires at 200 mm centres both ways, ten wires per metre in each direction. A7 is 3.02 kg/m², A9 4.99 kg/m² and A10 6.16 kg/m². Add the laps (usually 200 mm to 300 mm, or as the drawings say) and cutting waste when converting a slab area to tonnes ordered.
How is reinforcement measured in a bill of quantities?: Bar reinforcement by weight, as fixed, with the length taken from the bar-bending schedule or measured from the drawings including the laps shown; rolling margin, tying wire, spacers and chairs are deemed included in the rate. Mesh is measured by area, as fixed, with laps deemed included unless the bill says otherwise. On-screen take-off software such as Take-Off by WEQS gives the lengths and areas; the weight comes from these tables.

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Calculated from the nominal bar diameters and a steel density of 7,850 kg/m³. Check the mesh specification against the supplier's data sheet before ordering; wire sizes and sheet dimensions differ between manufacturers.