D²/162 rebar formula plus 8 steel sections
Steel Weight CalculatorTMT Bars, Plates, Pipes & Slab Steel
Work out the weight of any steel in seconds. Add several TMT bar sizes to one list, weigh plates, pipes, angles and bars in seven metals, or estimate the reinforcement for a slab. This steel weight calculator shows kilograms, tonnes, number of 12 m bars and the total cost, so ordering steel becomes simple.
- 11 bar sizes
- 8 section shapes
- 7 metals
- 3 tools in one
Sample price shown. Standard TMT bars are 12 m long.
Weight to length and weight check
An estimate for ordering, not a bar bending schedule. Uses the price per kg from the TMT bars tab.
How steel weight is calculated
Steel weight is simply volume multiplied by density. Mild steel weighs about 7,850 kg per cubic meter, so every shape comes down to its cross-section area times its length. For round bars, this reduces to the well-known D²/162 shortcut.
TMT / round bar
kg per m = D² ÷ 162.2Plate or sheet
kg = L × W × T (mm) × 7.85 ÷ 10⁶Round pipe
kg per m = (OD − t) × t × 0.02466Flat bar
kg per m = W × T × 0.00785Square bar
kg per m = A² × 0.00785Equal or unequal angle
kg per m ≈ (A + B − t) × t × 0.00785Where does 162 come from? A 1 m bar of diameter D mm has a volume of π × D² ÷ 4 mm² × 1 m. Multiplying by 7,850 kg/m³ and converting units gives D² ÷ 162.2 kg per meter. Angle weights ignore the small root radius.
TMT bar weight chart (kg per meter)
Nominal weights for standard 12 m TMT bars, based on D²/162.2. Use them to convert between kilograms, meters and number of bars when you order steel.
| Diameter | kg per meter | kg per 12 m bar | Bars per tonne | Meters per tonne |
|---|---|---|---|---|
| 6 mm | 0.222 | 2.66 | ~375 | ~4,505 |
| 8 mm | 0.395 | 4.74 | ~211 | ~2,534 |
| 10 mm | 0.617 | 7.40 | ~135 | ~1,622 |
| 12 mm | 0.888 | 10.65 | ~94 | ~1,126 |
| 16 mm | 1.578 | 18.94 | ~53 | ~634 |
| 20 mm | 2.466 | 29.59 | ~34 | ~405 |
| 25 mm | 3.853 | 46.24 | ~22 | ~260 |
| 32 mm | 6.313 | 75.76 | ~13 | ~158 |
Actual bars can weigh slightly more or less than nominal because of rolling tolerances. Use the weight check above to compare a real bar against the chart.
Metal densities used
| Metal | kg/m³ | g/cm³ |
|---|---|---|
| Mild steel / TMT | 7,850 | 7.85 |
| Stainless steel 304 | 7,930 | 7.93 |
| Stainless steel 316 | 8,000 | 8.00 |
| Aluminium | 2,700 | 2.70 |
| Copper | 8,960 | 8.96 |
| Brass | 8,500 | 8.50 |
| Cast iron | 7,200 | 7.20 |
More than a rebar weight calculator
Most steel calculators take one diameter and one length. This one handles a full order list, every common section and a whole slab, then puts a price on it.
Multi-size order list
Add as many bar sizes as you need and get totals per diameter, in kilograms, tonnes and 12 m bars.
Weight check
Weigh one bar on site and see how far it is from the nominal weight before you accept the delivery.
8 sections, 7 metals
Plates, round, square, flat and hex bars, pipes, tubes and angles in steel, stainless, aluminium, copper and more.
Slab steel estimate
Enter slab size, bar sizes and spacing to get main and distribution steel, with a live mesh drawing.
Instant costing
Add your price per kg once and every tab shows the total cost of the steel.
Reverse conversion
Turn a weight in kilograms into meters and number of bars, which helps when steel is billed by weight.
How to use the steel weight calculator
Pick a tab
Use TMT bars for reinforcement, Plates & sections for fabrication, or Slab steel for a full slab.
Enter sizes
Choose diameters or section dimensions, lengths and quantities. Add more bar sizes as needed.
Add a price
Type your price per kg to see the cost alongside the weight.
Copy and order
Copy the steel list and share it with your supplier or contractor.
Planning the concrete too? Use the concrete calculator for the slab and the brick calculator for the walls.
Benefits and steel buying tips
Buy by weight
Steel is priced per kg or tonne, so compare quotes on weight, not on the number of bars.
Check every delivery
Weigh a few bars of each size and compare them with the chart before unloading the truck.
Allow for laps
Laps, hooks and bends add length. Keep a margin so you do not run short mid-pour.
Store steel dry
Keep bars off the ground on wooden supports and covered, so they do not rust before use.
Ask for test certificates
Request the mill test certificate and check the grade marking on the bars.
Follow the design
Bar sizes and spacing for real structures must come from your structural engineer's drawings.
Steel weight calculator FAQs
What is the formula for steel bar weight?
Weight in kg per meter equals the diameter in millimeters squared, divided by 162. Multiply by the length in meters and the number of bars to get the total weight.
Why is 162 used in the steel weight formula?
It comes from the density of steel. A round bar's area is pi times D squared over 4. Multiplying by 7,850 kg per cubic meter and converting units leaves D squared divided by about 162.2.
What is the weight of a 12 mm steel bar?
A 12 mm bar weighs about 0.888 kg per meter, so a standard 12 m bar weighs around 10.66 kg.
How many 12 mm bars are there in 1 tonne?
One tonne of 12 mm steel is roughly 94 bars of 12 m each, or about 1,126 meters of bar.
How do I calculate the weight of an MS plate?
Multiply length, width and thickness in millimeters, then multiply by 7.85 and divide by one million to get kilograms. An 8 by 4 ft sheet that is 6 mm thick weighs about 140 kg.
What is the formula for steel pipe weight?
For a round steel pipe, weight in kg per meter equals the outer diameter minus the wall thickness, times the wall thickness, times 0.02466, with all sizes in millimeters.
How much steel is needed for a slab?
It depends on the bar sizes and spacing in the design. Enter the slab size, main and distribution bars and their spacing in the Slab steel tab to get the weight and the steel per square meter.
Why does the actual bar weight differ from the calculated weight?
Bars are rolled within a permitted weight tolerance, so real bars can be slightly lighter or heavier than nominal. Weigh a sample and use the weight check to see the difference.
Order steel with confidence
Steel is one of the biggest costs in any build. Use this steel weight calculator to check quantities, compare quotes and verify deliveries, so every kilogram you pay for ends up in the structure.