How Many TMT Bars Per Kg and Per Tonne for Different Diameters

“How many TMT bars per kg will I get?” is one of the most searched construction questions in India, asked daily by contractors verifying dealer deliveries, homeowners cross-checking quotes, and procurement teams reconciling weight against bundle count. The answer is not one fixed number. It depends on the diameter and bar length. But the calculation method remains the same for every size and every manufacturer because the TMT bar weight per metre is defined under IS 1786:2008. Once you understand the formula, you can quickly calculate how many steel rods are available per kg or per tonne for different diameters without relying entirely on dealer estimates.

The formula is based on weight per metre and bar length

Every TMT bar has a nominal weight per metre defined under IS 1786:2008. Standard retail bar length in India is usually 12 metres, while project supply lengths may vary depending on structural requirements.

Pieces per tonne = 1,000 ÷ (weight per metre × bar length)

Pieces per kg = 1 ÷ (weight per metre × bar length)

For an 8mm bar at 0.395 kg/m and 12 m length, each bar weighs:

0.395 × 12 = 4.74 kg

So:

1,000 ÷ 4.74 ≈ 211 pieces per tonne

Similarly:

1 ÷ 4.74 ≈ 0.21 bar per kg

This is the standard method used across the construction industry to calculate TMT bar quantity by diameter.

Complete diameter reference chart for 12-metre TMT bars

Use this chart while verifying dealer quotations, delivery challans, and bundle counts on-site. A 1 tonne TMT steel order containing mostly 8mm bars will contain significantly more individual pieces than the same tonnage ordered in 20mm or 25mm diameters.

How many bars are in one bundle of TMT steel

Bundle quantities vary based on diameter, manufacturer packing standards, and dealer handling practices.

8mm bundles typically contain around 10 bars and weigh approximately 48 kg.

10mm bundles generally contain around 10 bars.

12mm bundles usually contain around 5 to 10 bars, depending on dealer and manufacturer norms.

16mm and larger diameters are commonly supplied in smaller bundle counts because each individual bar carries significantly higher weight.

Before accepting delivery, always verify both bundle count and total invoice weight. Weight verification provides a more reliable reconciliation method than bundle count alone.

Understanding diameter mix in residential construction

Residential RCC construction generally uses a combination of 8mm, 10mm, 12mm, 16mm, and 20mm bars, depending on slab, beam, footing, and column requirements.

8mm bars are commonly used for stirrups and slab distribution steel.

10mm and 12mm bars are widely used for slab reinforcement in residential structures.

16mm and 20mm bars are typically used for beam and column reinforcement.

The final quantity mix depends on structural design, loading conditions, slab spans, and reinforcement detailing. This is why TMT bar prices per tonne should always be evaluated together with the diameter mix rather than as a single flat per-kg rate.

Frequently Asked Questions

Q1. How many 8mm bars are there in 1 tonne?

Approximately 211 pieces of 12-metre length, since 8mm bars weigh 0.395 kg per metre.

Q2. How many TMT bars per kg of 12mm diameter?

Approximately 0.094 of a 12-metre bar, or roughly one bar for every 10.65 kg.

Q3. Why does bundle count sometimes differ from invoice weight?

IS 1786 permits defined manufacturing tolerances based on diameter. Final reconciliation should always be done through weight verification.

Q4. Can I buy loose TMT bars instead of full bundles?