Picture a site supervisor checking a delivery of 16mm TMT bars. The truck slip says 5 tonnes. The bundles look right. But nobody has checked what one bar actually weighs.
That number decides how much steel is really inside your slab, beam or column. This chart gives it to you, along with the formula, the maths for your order, and a simple weight check on delivery day.
Quick answer: TMT bar weight per metre = D² ÷ 162, where D is the diameter in mm. That gives 0.395 kg/m for 8mm, 0.617 kg/m for 10mm, 0.888 kg/m for 12mm, 1.58 kg/m for 16mm and 2.47 kg/m for 20mm. A standard 12 m bar of 16mm weighs about 19 kg. Add 3 to 5% on top for cutting and bending wastage.
TMT Bar Weight Chart (8mm to 32mm)
| Diameter (mm) | Weight (kg/m) | Weight of a 12 m bar (kg) | Approx. bars per tonne (12 m) |
|---|---|---|---|
| 8 | 0.395 | 4.74 | 211 |
| 10 | 0.617 | 7.40 | 135 |
| 12 | 0.888 | 10.66 | 94 |
| 16 | 1.58 | 18.96 | 53 |
| 20 | 2.47 | 29.64 | 34 |
| 25 | 3.85 | 46.20 | 22 |
| 32 | 6.31 | 75.72 | 13 |
Figures are the nominal mass per metre used with IS 1786. Bars are commonly supplied in 12 m lengths, so confirm the length on your order. Fe 500, Fe 500D and Fe 550D weigh the same for the same diameter, because weight depends on diameter, not grade.
The Formula: Weight per Metre = D² ÷ 162
You can work out the weight of any diameter without a table.
- Square the diameter in mm. For 16mm, that is 16 × 16 = 256.
- Divide by 162. So 256 ÷ 162 = 1.58 kg per metre.
The 162 comes from the cross-section area of a round bar and the density of steel, about 7,850 kg per cubic metre. It is a good check when a supplier quotes a weight that looks off.
How to Turn This Into an Order
TMT is bought by weight, so the job is simple: total length required × weight per metre = kilograms to order. Then add wastage.
Example 1: Bars counted in pieces
You need 20 bars of 16mm, each 12 m long. That is 20 × 18.96 = 379.2 kg. Add 5% wastage and you order about 398 kg.
Example 2: A small slab
A 4 m × 3 m slab with 10mm bars at 150 mm spacing in both directions:
- Bars running along the 4 m side: 3 ÷ 0.15 + 1 = 21 bars × 4 m = 84 m
- Bars running along the 3 m side: 4 ÷ 0.15 + 1 ≈ 28 bars × 3 m = 84 m
- Total length: 168 m × 0.617 kg/m = about 104 kg
- With 5% wastage: about 109 kg
This is a rough estimate. It ignores cover, laps, bends and extra top steel. Your structural engineer’s bar bending schedule always decides the final quantity.
Converting tonnes to bars
Ordering by tonne? Multiply by the bars-per-tonne figure. Five tonnes of 12mm in 12 m lengths is about 5 × 94 = 470 bars.
Check the Weight on Delivery Day
A bar that weighs less than the table for its stated diameter is thinner than it claims. That means less steel area in your concrete, even if the bundle looks full. Before unloading:
- Weigh a few bars from different bundles and compare them with the chart. A 12 m bar of 16mm should be close to 19 kg.
- Ask for the weighbridge slip and match it with the invoice quantity.
- Count bars per bundle and compare with the bars-per-tonne column.
- Ask for the mill test certificate for that batch. Our TMT rebar buying guide explains what to look for.
The standard allows only a small tolerance on weight per metre. If bars are well below the chart, raise it before you accept the load.
Common Mistakes When Ordering TMT by Weight
- Ordering by bar count only. Two suppliers can both send 100 bars and deliver very different tonnage. Confirm both count and weight.
- Skipping wastage. Cutting and bending losses typically run 3 to 5%. Ordering the exact drawing weight means a rushed top-up mid-pour.
- Comparing rates without comparing weight per metre. A lower rate per tonne is not a saving if the bars are lighter than the table. More on this in our steel buying mistakes guide.
- Forgetting binding wire. Rebar is tied on site, so add MS binding wire to the same order.
Working with structural sections too? See our MS angle, channel and beam weight chart.
Frequently Asked Questions
What is the weight of 12mm TMT bar per metre?
About 0.888 kg per metre. A 12 m bar weighs roughly 10.66 kg.
How many 16mm bars are in one tonne?
About 53 bars, if each is 12 m long.
Does Fe 500D weigh more than Fe 500?
No. For the same diameter, the nominal weight per metre is the same. The grade changes the strength and ductility, not the weight.
How do I calculate the weight of any TMT bar?
Use D² ÷ 162 for kg per metre, where D is the diameter in mm. Multiply by the length in metres for the total.
How much extra TMT should I order for wastage?
Plan for 3 to 5% on top of the drawing quantity, and confirm against your structural engineer’s bar bending schedule.
Need TMT Rebars in Bhavnagar or Surat?
We stock TMT rebars across common grades and diameters, with mill test certification available on every batch. Tell us your diameter, length and quantity and we will confirm today’s stock and weight before you place the order. See also what local stock means for your project.
