Find the weight of TMT/steel bars using the standard IS 1786 formula, estimate cement bags/sand/aggregate for a concrete mix, or convert any material's volume to weight.
Key Takeaways
- TMT bar weight follows one simple formula everywhere in India: kg per metre = diameter² ÷ 162 (diameter in mm) — it comes directly from steel's density and needs no lookup table, though a reference table is still handy for quick site checks.
- Concrete needs about 54% more dry material volume than its final wet volume, which is why the standard 1.54 dry-volume factor is applied before splitting into cement, sand, and aggregate quantities — skipping this factor under-orders material by a third or more.
- A nominal mix ratio like M20 (1:1.5:3) is for quick estimation only. IS 456 requires an actual design mix, tested for the specific cement, sand, and aggregate being used, for any real M20-or-higher structural concrete.
What This Material Weight Calculator Does
This calculator handles three of the most common material-quantity questions in Indian construction. TMT/Steel Bar Weight uses the standard IS 1786 formula to convert a bar's diameter and length into its weight, for any number of bars at once. Concrete Mix Material takes a wet concrete volume and a mix ratio (M5 through M25, or a custom ratio) and works out how many cement bags, and how much sand and aggregate by weight, you'll need, using the standard 1.54 dry-volume factor. Volume to Weight is a general-purpose converter across common construction materials — steel, concrete, sand, bricks, timber, and more — using standard density figures.
Everything runs entirely in your browser. No dimension, grade, or material you select is sent to a server, logged, or stored anywhere — close the tab and it's gone. There's no signup, no email wall, and no ads inside the calculator itself. These are estimation tools for planning and quick site checks, not a substitute for a structural engineer's design mix or bill of quantities on an actual project.
How to Use This Material Weight Calculator
1. TMT / Steel Bar Weight
- Select the Bar Diameter (or enter a custom size).
- Enter the Length per Bar and Number of Bars.
- Read the total weight, plus weight per bar and per metre.
2. Concrete Mix Material
- Pick a Concrete Grade (or a custom ratio).
- Enter the Wet Concrete Volume you need to cast.
- Read the cement bags, sand, and aggregate quantities.
3. Volume to Weight
- Choose a Material from the list.
- Enter the Volume.
- Read the weight in kilograms, quintals, and tonnes.
The Material Weight Formulas, Explained
TMT/Steel Bar Weight: Weight per metre (kg/m) = Diameter² ÷ 162, where diameter is in millimetres. This comes directly from steel's density (7,850 kg/m³) applied to the bar's circular cross-sectional area.
Concrete Mix Material: for a mix ratio of a:b:c (cement:sand:aggregate) and a wet volume V, Dry Volume = V × 1.54. Each material's volume = (its ratio part ÷ total parts) × Dry Volume, then Weight = Volume × Density.
Volume to Weight: Weight = Volume × Density.
Worked example (TMT Bar Weight): 12mm diameter, 12m length, 10 bars.
- Weight per metre = 12² ÷ 162 ≈ 0.889 kg/m
- Weight per bar = 0.889 × 12 ≈ 10.67 kg
- Total weight = 10.67 × 10 ≈ 106.7 kg
Worked example (Concrete Mix, M20): 1 m³ wet volume, ratio 1:1.5:3 (5.5 total parts).
- Dry Volume = 1 × 1.54 = 1.54 m³
- Cement Volume = (1/5.5) × 1.54 ≈ 0.28 m³ → Weight = 0.28 × 1,440 ≈ 403.2 kg ≈ 8.06 bags (50 kg each)
- Sand Volume = (1.5/5.5) × 1.54 ≈ 0.42 m³ → Weight = 0.42 × 1,600 = 672 kg
- Aggregate Volume = (3/5.5) × 1.54 ≈ 0.84 m³ → Weight = 0.84 × 1,450 ≈ 1,218 kg
TMT Bar Weight Reference Table
Standard weight per metre and per 12m bar for common TMT diameters — a quick site reference without needing to calculate.
| Diameter | Weight per Metre | Weight per 12m Bar |
|---|---|---|
| 6 mm | 0.222 kg | 2.67 kg |
| 8 mm | 0.395 kg | 4.74 kg |
| 10 mm | 0.617 kg | 7.41 kg |
| 12 mm | 0.889 kg | 10.67 kg |
| 16 mm | 1.580 kg | 18.96 kg |
| 20 mm | 2.469 kg | 29.63 kg |
| 25 mm | 3.858 kg | 46.30 kg |
| 28 mm | 4.840 kg | 58.07 kg |
| 32 mm | 6.321 kg | 75.85 kg |
Quick Definitions
Nominal mix is a concrete mix specified by a fixed volumetric ratio of cement, sand, and aggregate (like 1:1.5:3 for M20), used for quick estimation and smaller, non-critical work. Design mix is a mix proportioned by actual laboratory testing of the specific materials being used to reliably achieve a target strength, and is mandatory under IS 456 for M20 grade concrete and above on real structural work.
Frequently Asked Questions
It comes from steel's density (7,850 kg/m³) combined with the formula for a circle's area, converted to consistent units of millimetres and metres. Working through the unit conversion mathematically lands on approximately 162.3, which is rounded to 162 in standard Indian civil engineering practice.
Dry cement, sand, and aggregate have air gaps between their particles that disappear once they're mixed with water and compacted into solid concrete. The 1.54 factor accounts for that volume reduction so you order enough dry material to actually produce your target wet volume.
IS 456 requires a design mix, tested with your actual cement, sand, and aggregate, for M20 grade and above on structural work. Nominal ratios are useful for quick material estimation and for smaller, non-structural applications like flooring or minor site work.
Yes, meaningfully. Sand density in particular changes with moisture content (wet sand can bulk up significantly compared to dry sand), and aggregate density varies somewhat by source and grading. The figures used here are standard estimation values, not a substitute for testing your specific material batch on a large project.
Most site estimators add a wastage allowance, commonly cited around 3–5% for steel (cutting offcuts) and a similar margin for cement and aggregate, on top of the calculated quantity. This calculator gives the theoretical requirement; add your own project's typical wastage margin when placing an actual order.
No. Every calculation runs locally in your browser using JavaScript; nothing you enter is transmitted to any server, logged, or saved once you close or refresh the page.