Steel stock is ordered by size but priced, shipped and lifted by weight. This calculator finds the weight of steel plate, flat bar, round and square bar, hex bar, pipe and tube, angle and sheet in carbon, mild, stainless, tool steel and cast or wrought iron, for one piece or a whole cut list.
How to use the Steel Weight Calculator
- Material
- Custom density
- Shape
- Width / diameter / side / leg
- Height (rectangular tube)
- Thickness / wall
- Sheet area
- Length
- Number of pieces
- Every result field is editable: type into Weight of one piece or any other result and Length plus every other field update to match.
Results update as you type, and every field accepts the units shown in its menu.
How it works
The calculator works out the cross-sectional area of the shape you choose, multiplies it by the length to get the volume, then by the density of the material to get the weight. Tubes subtract the hollow core; angles count both legs once.
Densities used
| Material | kg/m³ | lb/in³ | lb/ft³ |
|---|---|---|---|
| Carbon steel | 7,850 | 0.2836 | 490.1 |
| Mild steel | 7,870 | 0.2843 | 491.3 |
| Stainless steel 304 | 7,930 | 0.2865 | 495.1 |
| Stainless steel 316 | 8,000 | 0.2890 | 499.4 |
| Tool steel | 7,715 | 0.2787 | 481.6 |
| Wrought iron | 7,750 | 0.2800 | 483.8 |
| Cast iron | 7,200 | 0.2601 | 449.5 |
Good to know
Rule of thumb: steel plate weighs 7.85 kg per m² per mm of thickness, or 40.8 lb per ft² per inch.
Tips for an accurate estimate
- Sketch the job and split irregular areas into rectangles, circles and triangles before you measure.
- Add a waste allowance – typically 5–10% for simple layouts and 15–20% for diagonal, curved or heavily cut work.
- Check the coverage or yield printed on the product, because sizes and densities vary between manufacturers.
- Buy all units of a finished material (tile, brick, siding) from the same batch so colours match, and keep a few spares for repairs.
- Confirm local prices – quarry, lumber and steel prices vary widely by region and season.
Common mistakes to avoid
- Ordering exactly the calculated amount with no allowance for breakage, offcuts and settlement.
- Forgetting to subtract doors, windows and other openings – or subtracting small ones that still need cutting around.
- Confusing US short tons (2,000 lb) with metric tonnes (1,000 kg) when comparing quotes.
Inputs explained
| Field | What to enter |
|---|---|
| Material | Choose one: Carbon steel, Mild steel, Stainless steel 304, Stainless steel 316 … |
| Custom density | Units: kg/m³, lb/ft³, g/cm³, lb/yd³ |
| Shape | Choose one: Plate / flat bar (width × thickness), Round bar (diameter), Square bar (side), Hexagonal bar (across flats) … |
| Width / diameter / side / leg | Units: mm, in, cm |
| Height (rectangular tube) | Units: mm, in, cm |
| Thickness / wall | Units: mm, in, cm |
| Sheet area | Units: m², ft², yd² |
| Length | Units: m, ft, cm, in, yd |
| Number of pieces | A number |
Formula
Weight = cross-section area × length × density × piecesTube area = π/4 × (D² − (D − 2t)²)Angle area = t × (2a − t)Worked example
Inputs — Material: Carbon steel; Custom density: 7,850 kg/m³; Shape: Plate / flat bar (width × thickness); Width / diameter / side / leg: 100 mm; Height (rectangular tube): 50 mm; Thickness / wall: 10 mm; Sheet area: 1 m²; Length: 1 m; Number of pieces: 1.
Results — Cross-section area = 1,000 mm²; Volume of one piece = 1,000 cm³; Weight of one piece = 7.85 kg; Total weight = 7.85 kg; Weight per metre = 7.85 kg/m.
Frequently asked questions
How much does a steel plate weigh per square foot?
About 40.8 lb per ft² for each inch of thickness (≈ 7.85 kg/m² per mm).
What is the weight of a 1-inch round steel bar?
About 2.67 lb per foot (3.97 kg/m).
Is stainless steel heavier than mild steel?
Slightly – 304 stainless is about 7,930 kg/m³ versus 7,850 for carbon steel.
What formula does the Steel Weight Calculator use?
Weight = cross-section area × length × density × pieces.