MS flat weight chart

kg/m = width (mm) × thickness (mm) × 0.00785

Weight per metre of mild steel (MS) flat bar. A 50 × 6 mm flat weighs 50 × 6 × 0.00785 = 2.36 kg/m, so a 6 m length is 14.1 kg.

Download PDF Common sizes, 6 m bars FAQ

Metric flats (kg/m)

Width	3 mm	5 mm	6 mm	8 mm	10 mm	12 mm	16 mm	20 mm	25 mm
12 mm	0.28	0.47	0.57	0.75	0.94	1.13	—	—	—
16 mm	0.38	0.63	0.75	1.00	1.26	1.51	2.01	—	—
20 mm	0.47	0.78	0.94	1.26	1.57	1.88	2.51	3.14	—
25 mm	0.59	0.98	1.18	1.57	1.96	2.36	3.14	3.93	4.91
32 mm	0.75	1.26	1.51	2.01	2.51	3.01	4.02	5.02	6.28
40 mm	0.94	1.57	1.88	2.51	3.14	3.77	5.02	6.28	7.85
45 mm	1.06	1.77	2.12	2.83	3.53	4.24	5.65	7.06	8.83
50 mm	1.18	1.96	2.36	3.14	3.93	4.71	6.28	7.85	9.81
65 mm	1.53	2.55	3.06	4.08	5.10	6.12	8.16	10.20	12.76
75 mm	1.77	2.94	3.53	4.71	5.89	7.06	9.42	11.77	14.72
90 mm	2.12	3.53	4.24	5.65	7.06	8.48	11.30	14.13	17.66
100 mm	2.36	3.93	4.71	6.28	7.85	9.42	12.56	15.70	19.63
125 mm	2.94	4.91	5.89	7.85	9.81	11.77	15.70	19.63	24.53
150 mm	3.53	5.89	7.06	9.42	11.77	14.13	18.84	23.55	29.44
200 mm	4.71	7.85	9.42	12.56	15.70	18.84	25.12	31.40	39.25
250 mm	5.89	9.81	11.77	15.70	19.63	23.55	31.40	39.25	49.06
300 mm	7.06	11.77	14.13	18.84	23.55	28.26	37.68	47.10	58.87

Inch flats (lb/ft)

Width	1/8"	3/16"	1/4"	5/16"	3/8"	1/2"	3/4"	1"
1/2"	0.21	0.32	0.43	0.53	0.64	0.85	—	—
3/4"	0.32	0.48	0.64	0.80	0.96	1.28	1.91	—
1"	0.43	0.64	0.85	1.06	1.28	1.70	2.55	3.40
1-1/4"	0.53	0.80	1.06	1.33	1.59	2.13	3.19	4.25
1-1/2"	0.64	0.96	1.28	1.59	1.91	2.55	3.82	5.10
2"	0.85	1.28	1.70	2.13	2.55	3.40	5.10	6.80
2-1/2"	1.06	1.59	2.13	2.66	3.19	4.25	6.38	8.50
3"	1.28	1.91	2.55	3.19	3.82	5.10	7.65	10.20
4"	1.70	2.55	3.40	4.25	5.10	6.80	10.20	13.60
5"	2.13	3.19	4.25	5.31	6.38	8.50	12.75	17.00
6"	2.55	3.82	5.10	6.38	7.65	10.20	15.30	20.40
8"	3.40	5.10	6.80	8.50	10.20	13.60	20.40	27.20
10"	4.25	6.38	8.50	10.63	12.75	17.00	25.50	34.00
12"	5.10	7.65	10.20	12.75	15.30	20.40	30.60	40.80

Theoretical weights at 7850 kg/m³ (490 lb/ft³), square edges. Multiply by 1.01 for stainless steel 304 and by 0.344 for aluminum. steelweight-calculator.com

Common flat sizes: weight of a 6 m bar

Flats are usually stocked in 6 m lengths (some mills supply 5.5 m to 12 m). The last column turns a tonnage order into a number of bars.

Flat size	kg/m	6 m bar (kg)	6 m bars per tonne
25 × 3 mm	0.59	3.5	283
25 × 5 mm	0.98	5.9	170
32 × 5 mm	1.26	7.5	133
40 × 5 mm	1.57	9.4	106
40 × 6 mm	1.88	11.3	88
50 × 5 mm	1.96	11.8	85
50 × 6 mm	2.36	14.1	71
50 × 8 mm	3.14	18.8	53
50 × 10 mm	3.93	23.5	42
65 × 6 mm	3.06	18.4	54
65 × 8 mm	4.08	24.5	41
75 × 6 mm	3.53	21.2	47
75 × 8 mm	4.71	28.3	35
75 × 10 mm	5.89	35.3	28
100 × 6 mm	4.71	28.3	35
100 × 8 mm	6.28	37.7	27
100 × 10 mm	7.85	47.1	21
100 × 12 mm	9.42	56.5	18
150 × 10 mm	11.77	70.6	14
150 × 12 mm	14.13	84.8	12

How the flat bar formula works

A flat bar is a rectangle, so its weight is width × thickness × length × density. With the width and thickness in millimetres, one metre of bar has a volume of width × thickness × 1000 mm³, which is width × thickness cm³, and steel weighs 7.85 g/cm³. Putting the units together gives the factor 0.00785:

kg/m = w × t × 0.00785

Example: 50 × 6 mm gives 50 × 6 × 0.00785 = 2.355 kg/m, and a 6 m bar weighs 14.13 kg.

In inches the factor is 3.4: steel weighs 490 lb/ft³, and a 1 in × 1 in bar one foot long is 1/144 ft³, so it weighs 3.40 lb. A 2 × 1/4 in flat weighs 2 × 0.25 × 3.4 = 1.70 lb/ft, and a 20 ft bar about 34.0 lb.

Rolled flats have slightly rounded edges and a width tolerance, so the actual weight can be one or two percent lower or higher than the theoretical value. Use the theoretical weight for estimates and the supplier's weight for invoices.

Flat bars in other metals

The same formula works for any metal with its own density. Multiply the steel weight by the factor below; the last column is a 50 × 6 mm flat.

Material	Factor vs steel	50 × 6 mm (kg/m)
Stainless steel 304 / 316	1.010	2.38
Aluminum	0.344	0.81
Brass	1.083	2.55
Copper	1.141	2.69

Where flats are used

MS flats are used for base plates and gusset plates, bracing, brackets, gate and grille frames, handrails, earthing strips, cleats and general fabrication. Wider flats are used as stiffeners and as flanges of built-up members. For larger plates, see the steel plate weight chart; for any other shape, the steel weight calculator.

Frequently asked questions

What is the weight of a 50 × 6 mm MS flat?

50 × 6 × 0.00785 = 2.355 kg per metre, so a 6 m bar weighs about 14.13 kg.

What is the formula for flat bar weight?

Weight (kg/m) = width (mm) × thickness (mm) × 0.00785. The factor is the density of steel, 7850 kg/m³, converted for millimetres and metres. In inches, weight (lb/ft) = width (in) × thickness (in) × 3.4.

How much does a 25 × 3 mm flat weigh?

0.589 kg per metre; a 6 m length is about 3.53 kg.

How many 6 m lengths of 50 × 6 flat are there in a tonne?

About 71 bars: 1000 kg ÷ 14.13 kg per bar.

Does the formula work for stainless steel or aluminum flats?

Yes, with a different density. Multiply the steel weight by 1.010 for stainless steel 304 or 316, and by 0.344 for aluminum.

What is the difference between a flat bar and a strip or plate?

Flat bars are hot rolled to finished width with square or slightly rounded edges, usually up to about 150 mm wide (EN 10058, IS 1731). Wider or thinner material is cut from plate or coil and is sold as plate, strip or sheet; the weight formula is the same.