Weight of stainless round bar and rod

The formula is universal: the density of austenitic grades is close to 7.9 g/cm³, so 12Х18Н10Т, AISI 304 and AISI 316 give practically the same result.

Below — the formula, a table by diameters from 10 to 60 mm, the difference between calibrated and hot-rolled bar and the conversion of kilograms into metres.

Formula

Round bar is a cylinder, so the mass of a metre is calculated through the cross-sectional area:

m = ρ × π × d² / 4

Here ρ is the density, taken as 7.9 g/cm³ for stainless steel, and d is the diameter. If you substitute the density and convert millimetres into metres in advance, the formula reduces to a coefficient:

m = 0.0062 × d²

Example for ⌀20 mm round bar: 0.0062 × 400 = 2.48 kg per metre. A bar 6 m long weighs 14.9 kg, and 403 metres fit in a tonne.

The coefficient 0.0062 is a rounding of the exact value 0.0062046. For the reference steel density of 7.85 g/cm³ the coefficient is 0.006165. On a metre of ⌀20 round bar the discrepancy is about 16 grams, on a tonne — fractions of a percent, so in order calculations the rounding can be neglected.

Table by diameters: weight of 12Х18Н10Т round bar

Calculation for a density of 7.9 g/cm³, bar length — 6 m.

Diameter, mm	Weight of 1 m, kg	Metres per tonne	Weight of a 6 m bar, kg
10	0.62	1612	3.72
12	0.89	1119	5.36
14	1.22	822	7.30
16	1.59	630	9.53
18	2.01	497	12.06
20	2.48	403	14.89
22	3.00	333	18.02
25	3.88	258	23.27
28	4.86	206	29.19
30	5.58	179	33.51
32	6.35	157	38.12
35	7.60	132	45.60
38	8.96	112	53.76
40	9.93	101	59.56
42	10.95	91	65.67
45	12.56	80	75.39
50	15.51	65	93.07
55	18.77	53	112.61
60	22.34	45	134.02

This is the theoretical weight. It is needed to calculate the volume of an order and compare offers, but it does not replace the certificate: the actual mass of a batch depends on the tolerance for the diameter, and for hot-rolled rolled steel the tolerance is wider than for calibrated.

Calibrated and hot-rolled

Attribute	Hot-rolled	Calibrated
How it is produced	rolling at high temperature	cold drawing from a hot-rolled billet
Diameter accuracy	wider tolerance	stable size, tight tolerance
Surface	scale, rolling marks	smooth, bright
Straightness	limited	higher
Price	lower	higher
Where it goes	structures, turning with an allowance	automatic lathes, fasteners, precision parts

Hot-rolled round bar goes under ГОСТ 2590. Calibrated bar is made from the same billet but is drawn cold, so it is more accurate in size and holds a straight axis better.

The practical conclusion is simple. If a part is turned with an allowance, there is no point in paying extra for calibration — the tolerance will go into the swarf. If the bar goes into an automatic lathe without turning, saving on accuracy will turn into rejects and re-setting.

Metres per tonne

The conversion works in both directions and comes down to the mass of one metre.

• Metres to tonnes: length in metres × 0.0062 × d² / 1000.
• Tonnes to metres: 1000 / (0.0062 × d²).

Example. You need 2 tonnes of ⌀16 round bar. The mass of a metre is 1.59 kg, so there are 630 metres in a tonne, and 1260 metres in two tonnes. The reverse task: 500 metres of ⌀25 round bar is 500 × 3.88 = 1940 kg, that is 1.94 tonnes.

For sheet and pipe the logic is the same, but the formulas are different: there they calculate from the area and from the wall. The analysis is in the article on converting metres and m² into tonnes.

Frequently asked questions

How much does 12Х18Н10Т round bar weigh?

The mass of a metre depends only on the diameter: 0.0062 × d². For ⌀12 — 0.89 kg/m, for ⌀20 — 2.48 kg/m, for ⌀50 — 15.51 kg/m. The grade has almost no effect on the result, because the density of austenitic steels is similar.

How to calculate the weight of round bar by diameter?

Square the diameter in millimetres and multiply by 0.0062 — you get kilograms per metre. Multiply by the required length in metres and divide by 1000 to convert to tonnes. For a batch of several diameters, calculate each item separately.

How many metres of ⌀16 round bar are in a tonne?

About 630 metres. The weight of a metre of ⌀16 is 1.59 kg, so 1000 / 1.59 = 630. A bar 6 m long weighs 9.53 kg, that is 105 bars in a tonne.

How does calibrated round bar differ from hot-rolled?

In dimensional accuracy, surface and price. Calibrated bar is drawn cold; it holds its diameter and straightness, so it goes into automatic lathes and precision parts. Hot-rolled is cheaper and suitable for machining with an allowance.

Does the formula work for AISI 304 and 316?

Yes. The density of these grades is close to 7.9 g/cm³, the difference from 12Х18Н10Т is within the calculation error. If high accuracy is needed, take the density from the certificate of the specific batch and recalculate the coefficient.

Why does the actual weight of a batch differ from the calculated one?

The theoretical weight is calculated from the nominal diameter, while a real bar has a tolerance. Curvature and the actual length also have an effect. So acceptance is carried out by certificate and weighing, while the calculation is used for planning and the order.

Order stainless round bar

The GCX exchange catalogue has ⌀10–60 round bar of grades AISI 201, 304, 316L and 430. In the order state the diameter, grade, surface and shipment week — these parameters are transferred into the trade without renegotiation.

• Stainless round bar
• Converting metres and m² into tonnes
• HS codes
• How the exchange works
• Prices and quotations