8mm rod weight chart: TMT bar weight per metre and foot
MSME23 Oct 2026
An 8mm TMT bar weighs 0.395 kg per metre, or about 0.120 kg per foot, based on the nominal mass in IS 1786:2008. This reference covers the unit-weight formula behind that figure, a dedicated 8mm rod weight lookup, a full chart from 6 mm to 32 mm, the tolerances that apply to delivered bars, and how to use the chart to estimate an order.
Table of contents
How TMT bar weight is calculated
8mm rod weight per metre and per foot
Full TMT bar weight chart (6 mm to 32 mm)
Why actual weight can vary from the chart
Using the chart to estimate order quantity
The last word
Key takeaways
FAQs
How TMT bar weight is calculated
Steel weight per metre for any TMT bar diameter comes from one formula: weight (kg/m) = d² ÷ 162, where d is the nominal bar diameter in millimetres. IS 1786:2008 defines nominal mass using a steel density of 0.00785 kg per mm² of cross-sectional area per metre, and 162 is the rounded result of applying that density to a circular section (4 ÷ (π × 0.00785) ≈ 162.2).
The constant 162 is an industry convention, not a figure written into the standard. Because TMT bars carry surface ribs, the formula gives a nominal mass rather than the exact weight of every bar that leaves the rolling mill.
To get the weight per foot, multiply the per-metre result by 0.3048 (one foot is 0.3048 metres). For example, 0.395 kg/m × 0.3048 = 0.120 kg/ft.
8mm rod weight per metre and per foot
IS 1786:2008 lists a nominal mass of 0.395 kg per metre for the 8 mm size. Converted to feet, this is about 0.120 kg per foot, and a standard 12 m bar weighs about 4.74 kg.
Parameter | Value |
|---|---|
Diameter | 8 mm |
Weight per metre | 0.395 kg |
Weight per foot | 0.120 kg |
Weight per 12 m bar | 4.740 kg |
TMT bars in India are commonly supplied in 12 m lengths. If your supplier ships a different cut length, multiply the per-metre figure by the actual bar length. The 8 mm size is frequently used for stirrups, ties and secondary reinforcement, so this figure feeds directly into the small-diameter share of the steel estimate.
Full TMT bar weight chart (6 mm to 32 mm)
The table covers the common rebar diameters. Every nominal mass value comes from IS 1786:2008 Table 1; per-foot figures use the 0.3048 factor, and per-piece values assume a 12 m bar.
Diameter | Weight per metre (kg) | Weight per foot (kg) | Weight per 12 m bar (kg) |
|---|---|---|---|
6 mm | 0.222 | 0.068 | 2.664 |
8 mm | 0.395 | 0.120 | 4.740 |
10 mm | 0.617 | 0.188 | 7.404 |
12 mm | 0.888 | 0.271 | 10.656 |
16 mm | 1.580 | 0.482 | 18.960 |
20 mm | 2.470 | 0.753 | 29.640 |
25 mm | 3.850 | 1.173 | 46.200 |
28 mm | 4.830 | 1.472 | 57.960 |
32 mm | 6.310 | 1.923 | 75.720 |
The 12 mm (0.888 kg/m) and 16 mm (1.580 kg/m) values are among the most frequently looked up, alongside 8 mm and 10 mm. All follow the d² ÷ 162 formula above. IS 1786:2008 also lists 36 mm (7.99 kg/m) and 40 mm (9.86 kg/m) bars for heavier work.
This chart is a nominal reference. It does not replace the mill test certificate when you accept a bulk consignment.
Why actual weight can vary from the chart
Nominal mass is a calculated standard figure, not a promise that every bar in a delivered bundle will weigh the same. IS 1786:2008 (Table 2) allows for manufacturing variation through tolerance bands grouped by diameter:
Bars up to 10 mm: batch tolerance of ±7%; individual sample tolerance of −8%
Bars above 10 mm up to 16 mm: batch tolerance of ±5%; individual sample tolerance of −6%
Bars above 16 mm: batch tolerance of ±3%; individual sample tolerance of −4%
No plus tolerance is specified for individual samples. These allowances cover normal rolling variation in rib geometry and cross-sectional area; for how gauge consistency affects site quality, see our explainer on uniform gauge and dimension in TMT bars. For procurement, the mill test certificate links the delivered batch to the manufacturer's declared results and IS 1786:2008 conformance, so the weight chart should not be the only acceptance check on a large order.
Using the chart to estimate order quantity
Converting a bar-bending schedule into a purchase quantity takes four steps, with the chart supplying the kg/m value for each diameter.
Extract the total running length required for each diameter from the bar-bending schedule.
Multiply each diameter's total length by the corresponding kg/m value from the chart.
Add the diameter-wise weights together to get the total steel requirement in kilograms.
Divide by 1,000 to convert kilograms into metric tonnes.
Two practical points for procurement teams:
Build in a site-approved buffer for cutting waste, lap lengths, and bending losses. The appropriate percentage varies by project and should follow the engineer's recommendation rather than a generic rule.
Keep your estimate broken down by diameter. A single lump-tonnage figure without a diameter split can result in shortages on specific sizes when the order arrives on site.
For large orders, planning for bulk TMT delivery early helps avoid site delays.
What affects TMT bar prices
TMT bars are quoted per tonne, so the weight estimate converts directly into cost. The rate depends on base steel and billet prices, grade (such as Fe500D or Fe550D), diameter mix, order quantity, and delivery location and freight. Compare delivered cost for the full diameter schedule rather than a single headline rate.
The last word
The unit-weight formula and the chart above give a dependable starting point for converting bar lengths into kilograms and tonnes. For 8 mm rebar, the key figure is 0.395 kg/m; the full table covers 6 mm through 32 mm. Verify delivered weight against the supplier's mill test certificate, particularly on bulk orders where tolerance bands can shift totals.
Source TMT bars in the diameters you need on JSW One MSME
Key takeaways
An 8 mm TMT bar weighs 0.395 kg/m (about 0.120 kg/ft) under IS 1786:2008; a 12 m bar weighs about 4.74 kg.
Weight per metre = d² ÷ 162, derived from the IS 1786:2008 steel density of 0.00785 kg per mm² of cross-section per metre.
Delivered bars can vary within IS 1786:2008 batch tolerances: ±7% for bars up to 10 mm, ±5% up to 16 mm, and ±3% above 16 mm.
Estimate orders diameter by diameter from the bar-bending schedule, with a site-approved allowance for wastage and laps.
FAQs
1. What is the weight of an 8 mm TMT bar per metre?
The nominal mass per IS 1786:2008 is 0.395 kg/m. This density-derived figure is the standard reference used across the industry for estimation and procurement calculations.
2. What is the weight of an 8 mm TMT bar per foot?
Roughly 0.120 kg per foot, arrived at by multiplying the per-metre nominal mass of 0.395 kg by the conversion factor 0.3048.
3. How is TMT bar weight calculated from diameter?
Use d² ÷ 162, where d is the nominal diameter in millimetres. The result is weight in kg/m, based on the standard steel density of 0.00785 kg/mm² per metre of cross-section.
4. Does the standard TMT bar weight formula apply to all brands?
It gives a nominal figure valid across brands for standard diameters. Actual delivered weight may fall within IS 1786:2008 tolerance bands. Always verify against the supplier's batch documentation.
5. What is the standard length of a TMT bar sold in India?
Twelve metres is the most widely used commercial length and forms the basis for per-piece weight calculations in standard reference charts and procurement estimates.
6. How much does a 12 mm TMT bar weigh?
A 12 mm TMT bar weighs 0.888 kg/m, about 0.271 kg/ft, and roughly 10.656 kg for a 12-metre piece, based on IS 1786:2008 nominal mass values.
7. Why does actual TMT bar weight sometimes differ from the chart?
Charts show nominal mass. IS 1786:2008 permits tolerance bands that vary by diameter group, so individual bars and batches can weigh slightly more or less than the published figure.
8. How do I estimate the number of TMT bars needed for a project?
Total the running length per diameter from the bar-bending schedule, divide by the chosen bar length for a piece count, then multiply running length by kg/m for the weight estimate. Apply site-approved wastage allowances.
9. Where can I buy 8 mm TMT bars in bulk?
Through certified manufacturers, authorised distributors or B2B marketplaces such as JSW One MSME, where buyers select grade and diameter, request a quote, and track delivery and test certificates.