Steel plate is the backbone of fabrication work – base plates, gussets, decks and tanks. A handy shop rule says a 1-inch steel plate weighs 40.8 lb per square foot, or 7.85 kg per square metre per millimetre. Use this calculator for exact figures for any grade, size and quantity.
How to use the Steel Plate Weight Calculator
- Steel grade
- Custom density
- Plate length
- Plate width
- Thickness
- Number of plates
- Every result field is editable: type into Weight of one plate or any other result and Thickness 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
Choose the steel grade, enter the plate dimensions and number of plates. The calculator multiplies the volume by the density for that grade.
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 |
|---|---|
| Steel grade | Choose one: Carbon steel, Mild steel, Stainless steel 304, Stainless steel 316 … |
| Custom density | Units: kg/m³, lb/ft³, g/cm³, lb/yd³ |
| Plate length | Units: m, ft, cm, in, yd |
| Plate width | Units: m, ft, cm, in, yd |
| Thickness | Units: mm, in, cm |
| Number of plates | A number |
What each result means
- Area of one plate = [Plate length]×[Plate width]
- Total weight = [Weight of one plate]×[Number of plates]
Example values
How the main result changes when Thickness changes and everything else stays at the example values above:
| Thickness (mm) | Total weight (kg) |
|---|---|
| 5 | 122.66 |
| 7.5 | 183.98 |
| 10 | 245.31 |
| 12.5 | 306.64 |
| 15 | 367.97 |
| 20 | 490.63 |
Formula
Weight = length × width × thickness × 7,850 kg/m³ (carbon steel)Worked example
Inputs — Steel grade: Carbon steel; Custom density: 7,850 kg/m³; Plate length: 2.5 m; Plate width: 1.25 m; Thickness: 10 mm; Number of plates: 1.
Results — Area of one plate = 3.125 m²; Weight of one plate = 245.31 kg; Total weight = 245.31 kg; Weight per unit area = 78.5 kg/m².
Frequently asked questions
What is the weight of a 10 mm steel plate per m²?
78.5 kg/m² (16.1 lb/ft²).
Do stainless plates weigh more?
Yes, about 1–2% more than carbon steel of the same size.
Why do steel tables show a slightly different weight?
Mills roll to tolerances and some tables use 7,860 or 7,870 kg/m³; the difference is under 0.5%.
What formula does the Steel Plate Weight Calculator use?
Weight = length × width × thickness × 7,850 kg/m³ (carbon steel).