How to Calculate the Weight of Steel Bars

Knowing how to calculate the weight of steel bars helps you estimate your steel order, check deliveries and work out the cost. Steel bars (saria) are sold by weight, so a quick weight check tells you whether you are getting what you pay for. This guide gives the formula, a ready-made weight table for every common size, and worked examples.

Once you know the total weight, multiply it by the current steel rate per kg to estimate your cost, or use our steel rate calculator.

The Steel Bar Weight Formula

The quickest formula for a round steel bar is:

Weight (kg per metre) = D² ÷ 162

Here, D is the bar diameter in millimetres. To get the weight of a full bar, multiply by its length in metres:

Weight of bar (kg) = D² ÷ 162 × L

Where the formula comes from

The weight of any bar equals its volume multiplied by the density of steel, which is about 7,850 kg per cubic metre. The cross-section of a round bar is π × D² ÷ 4. When you convert millimetres to metres and multiply by 7,850, the result is 0.006165 × D² kg per metre, which is almost exactly D² ÷ 162.

Steel Bar Weight Table

The table below shows the nominal weight of each bar size, the weight of a standard 12-metre bar, and roughly how many 12-metre bars make one ton. The last column shows the cost of one 12-metre Grade 60 bar at today’s Kamran Steel rate of Rs 277 per kg.

Diameter	Bar no. (inch)	kg per metre	kg per 12 m bar	12 m bars per ton	Cost per 12 m bar (G60)
10 mm	#3 (3/8″)	0.617	7.41	135	Rs 2,052
12 mm	#4 (1/2″)	0.889	10.67	94	Rs 2,955
16 mm	#5 (5/8″)	1.580	18.96	53	Rs 5,253
20 mm	#6 (3/4″)	2.469	29.63	34	Rs 8,207
22 mm	#7 (7/8″)	2.988	35.85	28	Rs 9,931
25 mm	#8 (1″)	3.858	46.30	22	Rs 12,824
29 mm	#9 (1-1/8″)	5.191	62.30	16	Rs 17,256
32 mm	#10 (1-1/4″)	6.321	75.85	13	Rs 21,011
36 mm	#11 (1-3/8″)	8.000	96.00	10	Rs 26,592

Weights are nominal values from the formula. Costs are rounded, use today’s Kamran Steel Grade 60 ex-factory price, and exclude transport. For Grade 40 (Rs 275 per kg), costs are slightly lower.

Worked Examples

Example 1: weight of one bar

A 16 mm bar that is 12 metres long weighs 16² ÷ 162 × 12 = 256 ÷ 162 × 12 = 18.96 kg.

Example 2: weight and cost of an order

You need 50 bars of 12 mm, each 12 metres long. The weight is 50 × 10.67 kg = 533 kg. At Rs 277 per kg, the cost is about Rs 147,700, plus transport.

How to Use Weight to Check a Delivery

Pick a few bars from each bundle and measure their length.
Weigh them, or weigh the whole bundle on a proper scale.
Compare the result with the table above.

Under ASTM A615, a bar may not weigh less than 94% of its nominal weight. If your bars are much lighter than the table, they may be undersized or substandard. Read more about avoiding fake and substandard steel.

Common Mistakes to Avoid

Measuring the diameter over the ribs. Use the nominal size marked on the invoice or bar instead.
Mixing units. Keep the diameter in millimetres and the length in metres.
Forgetting laps and bends. Bar schedules add extra length for laps, hooks and bends, so the weight you buy is more than the straight-line length.

Plan Your Steel Order

For a whole house, see how much steel a 5, 7 or 10 marla house needs. Kamran Steel supplies Grade 40 and Grade 60 bars in all the sizes above, in standard 12-metre lengths. Contact our sales team for a quote.