Steel Weight Reference

Steel Bar Weight Table

Theoretical weight of steel bars (kg/m) based on specific gravity 7.85 g/cm³. Enter bar type, size and length in the calculator, or read the unit weight straight from the tables below.

kg/m theoretical unit weight, not a weighed figure 7.85 g/cm³ density used for every value Size diameter, side length or distance across flats

Quick weight calculator

Bar type

Size (mm)

Length (m)

Unit weight comes from the coefficients below. Total weight multiplies the unit weight by the length entered, and the result is a theoretical figure for estimating and quotation.

166 sizes listed

Round bar and square bar weight Unit weight for round bar and square bar from 5 to 300 mm, calculated from nominal size at a density of 7.85 g/cm³. Density varies a little by grade, and the measured values are in the tool steel density and thermal expansion chart.

Size (mm)	Round bar (kg/m)	Square bar (kg/m)
5	0.15	0.20
6	0.22	0.28
7	0.30	0.38
8	0.39	0.50
9	0.50	0.64
10	0.62	0.79
11	0.75	0.95
12	0.89	1.13
13	1.04	1.33
14	1.21	1.54
15	1.39	1.77
16	1.58	2.01
17	1.78	2.27
18	2.00	2.54
19	2.23	2.83
20	2.47	3.14
21	2.72	3.46
22	2.98	3.80
23	3.26	4.15
24	3.55	4.52
25	3.85	4.91
26	4.17	5.31
27	4.49	5.72
28	4.83	6.15
29	5.19	6.60
30	5.55	7.07
31	5.92	7.54
32	6.31	8.04
33	6.71	8.55
34	7.13	9.07
35	7.55	9.62
36	7.99	10.2
37	8.44	10.8
38	8.90	11.3
39	9.38	11.9
40	9.86	12.6
41	10.4	13.2
42	10.9	13.9
43	11.4	14.5
44	11.9	15.2
45	12.5	15.9
46	13.1	16.6
47	13.6	17.3
48	14.2	18.1
49	14.8	18.9
50	15.4	19.6
51	16.0	20.4
52	16.7	21.2
53	17.3	22.1
54	18.0	22.9
55	18.7	23.8
56	19.3	24.6
57	20.0	25.5
58	20.7	26.4
59	21.5	27.3
60	22.2	28.3
61	22.9	29.2
62	23.7	30.2
63	24.5	31.2
64	25.3	32.2
65	26.1	33.2
66	26.9	34.2
67	27.7	35.2
68	28.5	36.3
69	29.4	37.4
70	30.2	38.5
71	31.1	39.6
72	32.0	40.7
73	32.8	41.8
74	33.8	43.0
75	34.7	44.2
76	35.6	45.3
77	36.6	46.5
78	37.5	47.8
79	38.5	49.0
80	39.5	50.2
81	40.5	51.5
82	41.5	52.8
83	42.5	54.1
84	43.5	55.4
85	44.5	56.7
86	45.6	58.1
87	46.7	59.4
88	47.7	60.8
89	48.8	62.2
90	49.9	63.6
91	51.1	65.0
92	52.2	66.4
93	53.3	67.9
94	54.5	69.4
95	55.6	70.9
96	56.8	72.4
97	58.0	73.9
98	59.2	75.4
99	60.4	76.9
100	61.7	78.5
105	68.9	86.6
110	74.6	95.0
115	81.5	104
120	88.8	113
125	96.3	123
130	104	133
135	112	143
140	121	154
145	130	165
150	139	177
155	148	189
160	158	201
165	168	214
170	178	227
175	189	240
180	200	254
185	211	269
190	223	283
195	234	299
200	247	314
210	272	346
220	298	380
230	326	415
240	355	452
250	386	491
260	417	531
270	449	572
280	483	615
290	518	660
300	555	707

Hexagonal bar and octagonal bar weight Hexagonal and octagonal bar from 5 to 56 mm. Size is measured across the flats for both profiles.

Size (mm)	Hexagonal bar (kg/m)	Octagonal bar (kg/m)
5	0.17	0.16
6	0.25	0.23
7	0.33	0.32
8	0.44	0.42
9	0.55	0.53
10	0.68	0.65
11	0.82	0.79
12	0.98	0.94
13	1.15	1.10
14	1.33	1.27
15	1.53	1.46
16	1.74	1.66
17	1.97	1.88
18	2.20	2.11
19	2.45	2.35
20	2.72	2.60
21	3.00	2.87
22	3.29	3.15
23	3.60	3.44
24	3.92	3.74
25	4.25	4.06
26	4.60	4.40
27	4.96	4.74
28	5.33	5.09
29	5.72	5.47
30	6.12	5.85
31	6.53	6.25
32	6.96	6.66
33	7.41	7.08
34	7.86	7.52
35	8.33	7.97
37	9.31	8.90
39	10.3	9.89
41	11.4	10.9
43	12.6	12.0
45	13.8	13.2
47	15.0	14.4
50	17.0	16.3
53	19.1	18.3
56	21.3	20.4

Calculation basis

Specific gravity 7.85 g/cm³, standard for carbon and alloy steel. Round bar 0.00617 × d², square bar 0.00785 × d².

Size definition

Round and square bar, size is the diameter or the side length. Hexagonal and octagonal bar, size is the distance between opposite sides.

Weight adjustment by grade

Molybdenum HSS (M2, M35, M42) approx. +3%, tungsten HSS 18-4-1 type (T1) approx. +10%.

Related reference pages

Tool steel hardness conversion calculator · Tool steel properties chart · Tool steel material finder · How to select tool steels · Tool steel supply and stock sizes

Theoretical unit weights calculated from nominal dimensions at a density of 7.85 g/cm³. Actual weight varies with rolling tolerance, machining allowance and cutting loss, so use the figures for estimating and quotation.