The Shape Weight Calculator calculates how much a solid object weighs by multiplying its volume by the density of its material: W = V × ρ.
Choose a plate or flat bar, round bar, round tube, cone or sphere, enter its dimensions, and pick a material — steel, stainless steel, aluminum, copper, brass, cast iron, lead, concrete, water, HDPE — or enter a custom density. The calculator shows the weight and the volume it used.
Shape Weight Calculator
Weight of a plate, round bar, tube, cone or sphere from its dimensions and material — steel, aluminium, copper, concrete, plastic or a custom density.
Formula
Weight = Volume × Density
| Shape | Volume |
|---|---|
| Plate / flat bar | V = L × W × t |
| Round bar | V = (πd² ÷ 4) × L |
| Round tube | V = π(D² − d²) ÷ 4 × L, with d = D − 2t |
| Cone | V = πr²h ÷ 3 |
| Sphere | V = πd³ ÷ 6 |
Where: L = length, W = width, t = thickness, d = diameter, D = outer diameter, r = radius, h = height, ρ = density.
How the Calculation Works
Step 1: Calculate the volume of material from the dimensions.
Step 2: Convert the volume to cubic meters (or use matching units).
Step 3: Multiply by the density in kg/m³ to get the mass in kilograms, then convert to pounds or tons if needed.
Variables Explained
| Variable | Meaning | Unit |
|---|---|---|
| V | Volume of material | cm³, m³, in³, ft³ |
| ρ | Density | kg/m³, g/cm³, lb/ft³ |
| W | Weight (mass) | kg, g, t, lb, oz |
Example Calculation
Steel plate
Given: 100 cm × 20 cm × 1 cm, steel (7,850 kg/m³ = 7.85 g/cm³)
Volume: 100 × 20 × 1 = 2,000 cm³
Result: W = 2,000 × 7.85 = 15,700 g = 15.7 kg
Steel tube
Given: OD 5 cm, wall 0.3 cm, length 100 cm
Volume: π × (5² − 4.4²) ÷ 4 × 100 ≈ 442.97 cm³
Result: W ≈ 442.97 × 7.85 ≈ 3.48 kg
Steel ball
Given: diameter 10 cm
Result: V ≈ 523.60 cm³, W ≈ 4.11 kg
Material Density Table
Typical densities used in the calculator. Actual values vary with alloy, grade and moisture, so use a supplier’s figure when accuracy matters.
| Material | kg/m³ | g/cm³ |
|---|---|---|
| Steel | 7,850 | 7.85 |
| Stainless steel | 8,000 | 8.00 |
| Aluminum | 2,700 | 2.70 |
| Copper | 8,960 | 8.96 |
| Brass | 8,500 | 8.50 |
| Cast iron | 7,200 | 7.20 |
| Lead | 11,340 | 11.34 |
| Concrete | 2,400 | 2.40 |
| Water | 1,000 | 1.00 |
| HDPE plastic | 950 | 0.95 |
Engineering Assumptions
- Shapes are treated as solid and exact; holes, chamfers and coatings are not included.
- “Weight” here means mass (kg or lb), which is what scales and shipping quotes use.
Units and Dimensions
You can enter dimensions in mm, cm, m, in or ft and choose the weight unit. Density can be entered in kg/m³, g/cm³ or lb/ft³ when using a custom material.
Frequently Asked Questions
How do you calculate the weight of a shape?
Multiply its volume by the material density.
How do you calculate the weight of a steel plate?
Length × width × thickness × 7,850 kg/m³ (with dimensions in meters).
How much does a steel round bar weigh per meter?
(πd² ÷ 4) × 1 m × 7,850. A 20 mm bar weighs about 2.47 kg per meter.
How do you calculate the weight of a pipe or tube?
Use the ring-shaped cross-section: π(D² − d²) ÷ 4 × length × density.
What is the density of aluminum?
About 2,700 kg/m³ — roughly one third of steel.