A 3/8-inch carbon steel plate weighs about 15.3 lb per square foot, or 74.7 kg per square meter.
For the full breakdown, see our best 3/8 Metal Plate guide.
A full 4×8 sheet of 3/8 steel lands near 490 lb — heavy enough that freight quotes, forklift limits, and floor ratings all start to matter. Before you order, the one number that settles how much 3/8 steel plate weighs is 15.3 lb for every square foot of flat carbon steel, and it holds no matter how the sheet gets cut.
A 3/8 Steel Plate Weighs 15.3 Lb Per Square Foot: The Constant Behind Every Sheet
That figure covers flat plate rolled from carbon or mild steel of the type used in ASTM A36 and A572, the two most common structural grades sold in the US. Stainless and other alloys run a little different, so treat 15.3 lb/ft² as the baseline for ordinary steel plate.
The number comes straight from steel’s density. Most references assume 490 lb/ft³ (0.2836 lb/in³, or 7,850 kg/m³) for carbon steel, and the standard shortcut formula is thickness in inches × 40.8 = weight per square foot. For 3/8 inch: 0.375 × 40.8 = 15.3. Engineering ToolBox’s steel plate weight tables use the same density basis and shortcut, and supplier references from Alro and WeldBC list the identical 15.3 lb/ft² figure for 3/8-inch plate.
| Plate Thickness | Weight (lb Per Sq Ft) | Weight (kg Per Sq Meter) |
|---|---|---|
| 1/8 in | 5.1 lb | 24.9 kg |
| 3/16 in | 7.7 lb | 37.3 kg |
| 1/4 in | 10.2 lb | 49.8 kg |
| 5/16 in | 12.8 lb | 62.2 kg |
| 3/8 in | 15.3 lb | 74.7 kg |
| 1/2 in | 20.4 lb | 99.6 kg |
| 5/8 in | 25.5 lb | 124.5 kg |
| 3/4 in | 30.6 lb | 149.4 kg |
Working the math backward gives you the weight of any cut piece: multiply the sheet’s length in feet by its width in feet, then by 15.3. A 2×3 ft plate comes out to 91.8 lb; a 4×8 sheet comes out to 489.6 lb. These values assume plate rolled to its nominal 0.375-inch thickness — mill tolerances can shift a real sheet by a small percent.
How Heavy Is A Full 4×8 Sheet Of 3/8 Plate?
Close to 490 lb. That’s 32 square feet times 15.3 lb/ft², and most suppliers quote a standard 4×8 sheet of 3/8 carbon steel right around 490 lb, or roughly 222 kg.
That weight changes how you handle the sheet. 490 lb is not a two-person carry job even with the sheet split into halves; plan on a forklift, an engine hoist, or a delivery truck with a lift gate rated for the load. Floor limits matter too — a 4×8 sheet resting flat spreads the weight, but standing it on edge puts the full 490 lb on a narrow footprint. If you’re already comparing suppliers rather than doing the freight math, the best 3/8 metal plate options in our roundup cover the usual cut-to-size sellers and delivery considerations.
Does The Alloy Change The Weight?
Yes, but only slightly for common grades. Type 304 or 316 stainless steel runs about 2 percent denser than carbon steel, so a 3/8-inch stainless plate lands near 15.6 lb/ft² instead of 15.3 lb/ft².
Structural grades like A36 and A572 stay within a percent or so of the standard 15.3 figure. Exotic alloys and abrasion-resistant plate can differ more, which is why manufacturers publish density specs for their specific material. When the tolerance matters for a load calculation, use the alloy’s stated density in the length × width × thickness × density formula rather than relying on the carbon-steel shortcut.
FAQs
How much does 3/8 steel plate weigh per square inch?
A square inch of 3/8-inch carbon steel plate weighs about 0.106 lb, or roughly 1.7 ounces. That’s the 15.3 lb/ft² figure divided by 144 square inches per square foot, which is handy when you’re calculating small gussets or brackets cut from a larger sheet.
Why does my delivered 3/8 plate weigh a bit more or less than the estimate?
Mills roll plate to a nominal 0.375-inch thickness but allow small manufacturing tolerances, so the actual sheet can run a few percent over or under the published weight. Surface scale, mill finish, and minor alloy variations inside the same grade add another small margin to the real delivered weight.
What does a 3/8 steel plate weigh in metric units?
One square meter of 3/8-inch carbon steel plate weighs about 74.7 kg. A full 4×8 sheet (which is roughly 2.44 m × 1.22 m, or about 2.97 m²) scales to roughly 222 kg, matching the common 490 lb quote for a standard sheet.
References & Sources
- Engineering ToolBox. “Steel Plates – Size & Weight.” Source for the 490 lb/ft³ density basis, the thickness × 40.8 shortcut, and standard plate weights per square foot.