Short answer: The theoretical weight of a solid MS circle is weight (kg) = 0.006165 × D² × t ÷ 1000, with the diameter D and the thickness t in mm. For a ring, use (OD² − ID²) in place of D². The formula uses the steel density of 7.85 g/cm³ (7850 kg/m³) that Indian steel standards use to calculate mass. A 500 mm circle 25 mm thick weighs about 38.5 kg, and a 1200 mm circle 100 mm thick weighs about 888 kg. These are theoretical weights: a gas-cut circle can weigh a little more or less, and the weighbridge weight is what gets billed.
MS circle weight calculator
Enter the size of a solid circle. The weight updates as you type.
This page is for fabricators, flange and machine shops, and traders who buy MS circles by weight and need to estimate the weight of an order before asking for a quote. Use the calculator above for any size, or the chart below for common sizes.
Where the formula comes from
A circle is a disc: its volume is its face area times its thickness.
- Face area of a circle = π ÷ 4 × D².
- Volume = π ÷ 4 × D² × t.
- Weight = volume × density.
Density. IS 2062:2011, the Indian standard for structural steel plate, says: "The mass of steel shall be calculated on the basis that steel weighs 7.85 g/cm³" (IS 2062:2011, clause 18). 7.85 g/cm³ is the same as 7850 kg/m³, or 0.00000785 kg per mm³.
Putting it together with D and t in mm:
Weight (kg) = π ÷ 4 × D² × t × 0.00000785
π ÷ 4 × 0.00000785 = 0.000006165, so:
Weight (kg) = 0.006165 × D² × t ÷ 1000
For a ring (a circle with a hole), take away the hole:
Weight (kg) = 0.006165 × (OD² − ID²) × t ÷ 1000
A quicker way for a solid circle: find the weight per mm of thickness in the table below and multiply it by the thickness.
MS round plate, circular plate and ring weight
An MS round plate, circular plate or circle plate is the same thing as an MS circle: a disc cut from plate. The same formula gives its weight, and the calculator above works for it.
For a ring (a round plate with a hole in the centre), work out the solid circle at the OD and take away the circle at the ID, or use (OD² − ID²) directly. Example: a ring of 600 mm OD, 300 mm ID and 25 mm thickness:
- OD² − ID² = 360,000 − 90,000 = 270,000
- × thickness 25 = 6,750,000
- × 0.006165 ÷ 1000 = about 41.6 kg
Check: a solid 600 mm circle 25 mm thick weighs 55.5 kg, and the 300 mm hole would weigh 13.9 kg; 55.5 − 13.9 = 41.6 kg.
Worked example: 1045 mm circle, 50 mm thick
- D² = 1045 × 1045 = 1,092,025
- × thickness 50 = 54,601,250
- × 0.006165 = 336,617
- ÷ 1000 = about 337 kg
Check with the per-mm table: 6.733 kg per mm × 50 mm = 336.7 kg.
Weight per mm of thickness
Multiply by the thickness in mm to get the weight of one solid circle in kg.
| Diameter (mm) | kg per mm of thickness |
|---|---|
| 100 | 0.062 |
| 200 | 0.247 |
| 300 | 0.555 |
| 400 | 0.986 |
| 500 | 1.541 |
| 600 | 2.220 |
| 700 | 3.021 |
| 800 | 3.946 |
| 900 | 4.994 |
| 1000 | 6.165 |
| 1045 | 6.733 |
| 1100 | 7.460 |
| 1200 | 8.878 |
MS circle weight chart (kg per piece)
Theoretical weight of one solid circle, in kg, at 7.85 g/cm³. Values are rounded to three significant figures.
Thickness 6 to 16 mm
| Diameter (mm) | 6 mm thick | 10 mm thick | 12 mm thick | 16 mm thick |
|---|---|---|---|---|
| 100 | 0.37 | 0.62 | 0.74 | 0.99 |
| 200 | 1.48 | 2.47 | 2.96 | 3.95 |
| 300 | 3.33 | 5.55 | 6.66 | 8.88 |
| 400 | 5.92 | 9.86 | 11.8 | 15.8 |
| 500 | 9.25 | 15.4 | 18.5 | 24.7 |
| 600 | 13.3 | 22.2 | 26.6 | 35.5 |
| 700 | 18.1 | 30.2 | 36.3 | 48.3 |
| 800 | 23.7 | 39.5 | 47.4 | 63.1 |
| 900 | 30.0 | 49.9 | 59.9 | 79.9 |
| 1000 | 37.0 | 61.7 | 74.0 | 98.6 |
| 1045 | 40.4 | 67.3 | 80.8 | 108 |
| 1100 | 44.8 | 74.6 | 89.5 | 119 |
| 1200 | 53.3 | 88.8 | 107 | 142 |
Swipe sideways to see the whole table.
Thickness 20 to 40 mm
| Diameter (mm) | 20 mm thick | 25 mm thick | 32 mm thick | 40 mm thick |
|---|---|---|---|---|
| 100 | 1.23 | 1.54 | 1.97 | 2.47 |
| 200 | 4.93 | 6.17 | 7.89 | 9.86 |
| 300 | 11.1 | 13.9 | 17.8 | 22.2 |
| 400 | 19.7 | 24.7 | 31.6 | 39.5 |
| 500 | 30.8 | 38.5 | 49.3 | 61.7 |
| 600 | 44.4 | 55.5 | 71.0 | 88.8 |
| 700 | 60.4 | 75.5 | 96.7 | 121 |
| 800 | 78.9 | 98.6 | 126 | 158 |
| 900 | 99.9 | 125 | 160 | 200 |
| 1000 | 123 | 154 | 197 | 247 |
| 1045 | 135 | 168 | 215 | 269 |
| 1100 | 149 | 187 | 239 | 298 |
| 1200 | 178 | 222 | 284 | 355 |
Swipe sideways to see the whole table.
Thickness 50 to 100 mm
| Diameter (mm) | 50 mm thick | 63 mm thick | 80 mm thick | 100 mm thick |
|---|---|---|---|---|
| 100 | 3.08 | 3.88 | 4.93 | 6.17 |
| 200 | 12.3 | 15.5 | 19.7 | 24.7 |
| 300 | 27.7 | 35.0 | 44.4 | 55.5 |
| 400 | 49.3 | 62.1 | 78.9 | 98.6 |
| 500 | 77.1 | 97.1 | 123 | 154 |
| 600 | 111 | 140 | 178 | 222 |
| 700 | 151 | 190 | 242 | 302 |
| 800 | 197 | 249 | 316 | 395 |
| 900 | 250 | 315 | 400 | 499 |
| 1000 | 308 | 388 | 493 | 617 |
| 1045 | 337 | 424 | 539 | 673 |
| 1100 | 373 | 470 | 597 | 746 |
| 1200 | 444 | 559 | 710 | 888 |
Swipe sideways to see the whole table.
Why the real weight differs from the chart
The chart gives the weight of a perfect disc at the nominal size. A gas-cut circle is not perfect:
- Plate thickness is not exact. IS 2062 says rolling tolerances follow IS 1852 unless the buyer and the mill agree otherwise (IS 2062:2011). A "25 mm" plate can be slightly thicker or thinner, and weight changes in step with thickness.
- The cut edge is not square. Oxy-fuel cutting burns away a kerf and leaves some oxide dross on the edge (TWI). On thick plate the edge can taper, so the diameter at the top and bottom faces differs slightly. ISO 9013 is the standard that classifies thermal cuts and their tolerances (ISO 9013).
- Oversize for machining. If you order a rough circle with a machining allowance, the supplied diameter is larger than the finished diameter. Calculate the weight on the supplied size, not the drawing size.
So use the chart to plan and compare quotes, and use the weighbridge slip for billing. Agree before loading which weight counts.
Blank weight vs finished weight
A circle is cut from a square of plate. The circle is π ÷ 4, or about 78.5%, of the square around it. For example, a 500 × 500 mm square of 25 mm plate weighs about 49.1 kg, against 38.5 kg for the 500 mm circle cut from it. When you compare two quotes, check whether each is on the finished circle weight or on the plate weight, and who keeps the offcuts.
How to order gas-cut MS circles
Send these details, and the weight estimate from this chart, in one message:
- Diameter (OD) in mm, and the ID if you need rings
- Thickness in mm
- Number of pieces of each size
- Finished or rough size, and the machining allowance per side if rough
- Grade and whether you need a mill test certificate, if your drawing calls for one
- Delivery location and the date needed
Our guide Gas-cut MS circles: sizes, tolerances and how to order explains tolerances, IS 2062 grades and the machining allowance in more detail.
At J.S. STEEL we gas-cut MS circles from 100 mm to 1200 mm diameter and 6 mm to 100 mm thick at our Bhavnagar yard. Ready stock includes 1045 mm and 1200 mm circles, and we cut other circle sizes in that range to order. We send photos of the exact material before every load, and every truck load goes with a GST tax invoice (an e-invoice for GST-registered buyers), an e-way bill when the consignment requires one, and a weighbridge slip.
Frequently asked questions
What is the MS circle weight formula in kg?
Weight (kg) = 0.006165 × D² × t ÷ 1000, with the diameter D and the thickness t in mm. It uses the steel density of 7.85 g/cm³. For example, a 500 mm circle 20 mm thick weighs about 30.8 kg.
How do I calculate the weight of an MS ring?
Use (OD² − ID²) in place of D²: weight (kg) = 0.006165 × (OD² − ID²) × t ÷ 1000. A ring of 600 mm OD, 300 mm ID and 25 mm thickness weighs about 41.6 kg.
How much does a 1200 mm MS circle weigh?
About 8.88 kg for every mm of thickness. A 1200 mm circle 25 mm thick weighs about 222 kg, and one 100 mm thick weighs about 888 kg. These are theoretical weights.
Why is the weighbridge weight different from the calculator?
The calculator gives the weight of a perfect disc at the nominal size. Real plate thickness varies within the rolling tolerance, a gas-cut edge has kerf and dross, and rough circles are cut oversize for machining. The weighbridge weight is what gets billed.