Round Plate Weight Calculator

How to Calculate Circle Plate Weight

A circular plate (round disc) uses the formula Weight = π/4 × D² × Thickness × Density. This is the same as calculating the volume of a cylinder and multiplying by density. The π/4 factor (≈ 0.7854) converts the square of the diameter into the area of the circle.

For example, a 300mm diameter × 10mm thick MS circle plate weighs: π/4 × 0.3² × 0.01 × 7850 = 5.55 kg.

A quick mental shortcut: a circular plate weighs approximately 78.54% of a square plate with the same side length as the circle's diameter. So if you know the weight of a square plate, multiply by 0.785 to get the circle plate weight.

Circle Plate Weight Chart (MS, 10mm Thick)

Ring & Flange Blank Weight Calculation

Flanges, ring plates, and washers are essentially circular plates with a center hole. To calculate their weight, you need to find the weight of the outer disc and subtract the weight of the inner hole disc.

Ring Weight = π/4 × (OD² − ID²) × Thickness × Density

For example, a flange blank with 400mm OD × 200mm ID × 20mm thick in Mild Steel:

Outer disc = π/4 × 0.4² × 0.02 × 7850 = 19.72 kg. Inner hole = π/4 × 0.2² × 0.02 × 7850 = 4.93 kg. Ring weight = 19.72 − 4.93 = 14.79 kg.

This calculator gives you the solid disc weight. For ring flanges, calculate twice (once for OD, once for ID) and subtract manually. Common flange sizes in India follow IS 6392 (steel pipe flanges, PN ratings) and ASME B16.5 (Class 150/300… for process and export projects). The table below shows ASME B16.5 Class 150 dimensions — PN-rated flanges have different ODs.

Common Flange Blank Sizes — ASME B16.5 Class 150

Blank thickness is indicative (finished flange thickness plus machining allowance) — check the flange type and drawing. For a PN16 flange (EN 1092-1 / IS 6392), a 50 NB flange has 165mm OD and 125mm PCD.

Where Are Circle Plates Used?

Circular plates and round discs are one of the most widely used shapes in industrial fabrication. Unlike rectangular plates which are used as-is from stock, circle plates are always cut-to-order from standard rectangular sheets using flame cutting, plasma cutting, laser cutting, or waterjet cutting.

Circle Plate Weight Chart — Multiple Thicknesses (MS)

Below is a comprehensive weight chart for MS circle plates across commonly used diameters and thicknesses. All weights are in kg and calculated using density 7850 kg/m³.

For SS 304, add approximately 1% to these values. For Aluminium, multiply by 0.344 (density ratio 2700/7850). For Copper, multiply by 1.139 (density ratio 8940/7850).