A steel plate weighs 7.85 kg per square metre for every millimetre of thickness, or 40.8 lb per square foot for every inch. That one rule covers most of what you need. Use the calculator below for exact sizes, other alloys and quantities, or jump straight to the weight chart.
Steel plate weight formula
Metric
Weight (kg) = Length (m) × Width (m) × Thickness (mm) × 7.85
The 7.85 comes from steel’s density: 7,850 kg/m³ is 7.85 kg per m² per mm of thickness. For another material, swap in its own figure — 2.70 for aluminium 6061, 8.00 for stainless 304.
Imperial
Weight (lb) = Length (ft) × Width (ft) × Thickness (in) × 40.8
40.8 is steel’s 0.2836 lb/in³ multiplied by the 144 square inches in a square foot.
Worked example
A 2,000 × 1,000 mm mild steel plate, 12 mm thick.
- Area = 2.0 × 1.0 = 2 m²
- Weight per m² = 12 × 7.85 = 94.2 kg/m²
- Weight = 2 × 94.2 = 188.4 kg
Same plate in aluminium 6061: 12 × 2.70 = 32.4 kg/m² → 64.8 kg. That difference is why the alloy field matters more than the decimal places.
In imperial: a 4 ft × 8 ft plate at 1/4 inch.
- Area = 32 ft²
- Weight per ft² = 0.25 × 40.8 = 10.2 lb/ft²
- Weight = 32 × 10.2 = 326 lb
Steel plate weight chart — metric
Mild steel, 7,850 kg/m³.
| Thickness (mm) | kg per m² | 1000×2000 mm sheet (kg) | 1500×3000 mm sheet (kg) | 2000×6000 mm plate (kg) |
|---|---|---|---|---|
| 1 | 7.85 | 15.7 | 35.3 | 94.2 |
| 1.5 | 11.78 | 23.6 | 53.0 | 141.3 |
| 2 | 15.70 | 31.4 | 70.7 | 188.4 |
| 2.5 | 19.63 | 39.3 | 88.3 | 235.5 |
| 3 | 23.55 | 47.1 | 106.0 | 282.6 |
| 4 | 31.40 | 62.8 | 141.3 | 376.8 |
| 5 | 39.25 | 78.5 | 176.6 | 471.0 |
| 6 | 47.10 | 94.2 | 212.0 | 565.2 |
| 8 | 62.80 | 125.6 | 282.6 | 753.6 |
| 10 | 78.50 | 157.0 | 353.3 | 942.0 |
| 12 | 94.20 | 188.4 | 423.9 | 1,130.4 |
| 15 | 117.75 | 235.5 | 529.9 | 1,413.0 |
| 16 | 125.60 | 251.2 | 565.2 | 1,507.2 |
| 20 | 157.00 | 314.0 | 706.5 | 1,884.0 |
| 25 | 196.25 | 392.5 | 883.1 | 2,355.0 |
| 30 | 235.50 | 471.0 | 1,059.8 | 2,826.0 |
| 40 | 314.00 | 628.0 | 1,413.0 | 3,768.0 |
| 50 | 392.50 | 785.0 | 1,766.3 | 4,710.0 |
Steel plate weight chart — imperial
| Thickness | lb per ft² | 4×8 ft sheet (lb) | 5×10 ft plate (lb) |
|---|---|---|---|
| 1/8″ (0.125) | 5.10 | 163 | 255 |
| 3/16″ (0.1875) | 7.66 | 245 | 383 |
| 1/4″ (0.250) | 10.21 | 327 | 511 |
| 5/16″ (0.3125) | 12.76 | 408 | 638 |
| 3/8″ (0.375) | 15.31 | 490 | 766 |
| 1/2″ (0.500) | 20.42 | 653 | 1,021 |
| 5/8″ (0.625) | 25.53 | 817 | 1,276 |
| 3/4″ (0.750) | 30.63 | 980 | 1,532 |
| 1″ (1.000) | 40.84 | 1,307 | 2,042 |
Plate weight for other materials
Weight per square metre, per millimetre of thickness:
| Material | kg/m² per mm | lb/ft² per inch |
|---|---|---|
| Carbon / mild steel | 7.85 | 40.8 |
| Stainless steel 304 / 316 | 8.00 | 41.6 |
| Aluminium 6061 | 2.70 | 14.0 |
| Aluminium 5052 | 2.68 | 13.9 |
| Copper | 8.96 | 46.6 |
| Brass C360 | 8.50 | 44.2 |
| Titanium Grade 2 | 4.51 | 23.4 |
Multiply by thickness, then by area. A 3 mm stainless sheet is 24 kg/m²; the same sheet in aluminium is 8.1 kg/m² — one is a two-man lift, the other is not.
Rolling tolerance: why the delivery note never matches
Plate is rolled to a thickness tolerance, not to an exact number. A nominal 10 mm plate delivered at 10.3 mm is inside spec and 3 % heavier than the chart. Mills also work to a mass tolerance on the whole order.
What this means in practice:
- Estimating and quoting — nominal weight is fine, and it is what the supplier quotes against.
- Crane and rigging — add a margin. Do not plan a lift at exactly the calculated figure.
- Reconciling a delivery — a few percent over nominal is normal, not an error.
FAQ
How much does a 4×8 sheet of steel weigh? It depends on the thickness. A 1/8″ 4×8 sheet is about 163 lb, 1/4″ is about 327 lb, and 1/2″ is about 653 lb. Multiply the plate’s lb/ft² figure by 32.
How much does a 1 m² steel plate weigh? 7.85 kg for every millimetre of thickness. A 1 m² plate at 6 mm is 47.1 kg.
Is 7.85 or 7.86 the right density for steel? Both are used. 7,850 kg/m³ is the standard figure for carbon steel and is what suppliers quote against; the difference against 7,860 is 0.1 %, far smaller than the rolling tolerance.
Does the calculator handle sheet metal gauges? Convert the gauge to a thickness first — see the sheet metal gauge chart — then enter that thickness here. A gauge number is not the same thickness in steel, stainless and aluminium.
How do I work out the cost? Weight × price per kg (or per lb). The iOS app has a price field and gives you the cost with the weight.
Take it to the shop floor
Steel Metal Weight Calculator for iPhone and iPad: 30+ materials, plate, pipe, tube, bar, rebar and full structural section catalogues, saved projects, price per kg and PDF export. Works offline.