Calculate the weight of steel reinforcement bars (rebar) from the bar diameter, length, and quantity.
How to Use the Steel Weight Calculator
Enter the "Bar Diameter (mm)" - common TMT sizes are 8, 10, 12, 16, 20, 25, and 32mm.
Enter the "Length Per Bar (m)" - standard TMT bars are usually sold in 12m lengths.
Enter the "Number of Bars".
Click "Calculate Weight" to see the weight per meter, per bar, and the total weight.
Where the D² ÷ 162 Formula Comes From
A steel bar is a long cylinder, so its weight is cross-sectional area × length × density. For a bar of diameter D mm, the area is π × D² ÷ 4 mm². Multiply by 1 metre of length and by the density of steel, 7,850 kg/m³, and the constants collapse to D² × 0.006165, which is the same as D² ÷ 162.2. Rounding that to 162 gives the formula site engineers in India have used for decades.
The calculator then multiplies the weight per metre by the bar length to get the weight of one bar, and by the number of bars for the total. It also shows the total in quintals (1 quintal = 100 kg), since steel dealers in many places quote rates per quintal or per tonne.
Standard Weights of TMT Bars
Weights from the D² ÷ 162 formula for common rebar diameters, using the standard 12 m length:
Diameter (mm)
kg per metre
kg per 12 m bar
Bars per tonne (approx.)
6
0.222
2.67
375
8
0.395
4.74
211
10
0.617
7.41
135
12
0.889
10.67
94
16
1.580
18.96
53
20
2.469
29.63
34
25
3.858
46.30
22
32
6.321
75.85
13
Notice that weight rises with the square of the diameter: a 16 mm bar is twice the diameter of an 8 mm bar but weighs four times as much per metre.
Worked Example
Suppose a slab schedule calls for 50 bars of 12 mm, each 12 m long. Weight per metre = 12 × 12 ÷ 162 = 0.889 kg. One bar = 0.889 × 12 = 10.667 kg. Total = 10.667 × 50 = 533.33 kg, which is 5.333 quintals or just over half a tonne. At a dealer rate quoted per kg, multiply 533.33 by the rate to estimate the bill before GST and transport.
Things to Keep in Mind
Actual bars can weigh slightly more or less than the formula. IS 1786, the Indian standard for high-strength deformed bars, allows a small tolerance on mass per metre, with a wider tolerance for thin bars than for thick ones. Weighing a few bars from a delivery is a simple way to check you are getting what you paid for.
Steel is billed by weight, but the bar bending schedule is drawn up in lengths. Convert the schedule to weight with this tool before comparing quotes from different dealers.
Add an allowance for laps, hooks and cutting offcuts. The extra depends on the design and the bar lengths, so take it from your engineer or bar bending schedule rather than guessing.
The formula applies to plain round bars and TMT bars of any grade, such as Fe 415, Fe 500 or Fe 550. Grade changes the strength, not the weight.
Frequently Asked Questions
It uses the standard rebar weight formula: Weight per meter (kg/m) = D² ÷ 162, where D is the bar diameter in millimeters. This is derived from the density of steel (7,850 kg/m³) and the cross-sectional area of a round bar.
12 meters is the most common standard manufacturing and transport length for TMT bars in India, though other lengths are sometimes available - check with your supplier and adjust the "Length Per Bar" field accordingly.
Use the TMT Bar Calculator instead - it works in reverse, taking a total steel weight requirement (e.g. from the RCC Calculator) and telling you how many standard bars of a chosen diameter you need to order.
A 12 m long, 12 mm bar weighs about 10.67 kg, so one tonne contains roughly 94 bars. For 8 mm bars it is about 211, and for 16 mm bars about 53.
No. All grades of TMT bar have practically the same density, so a bar of a given diameter and length weighs the same regardless of grade. The grade only indicates its yield strength.