Standard Plate Thickness Chart
Fractional-inch plate thicknesses from 3/16 to 6 in, their exact millimeter values and the nearest common metric plate, and which thicknesses U.S. distributors usually carry in A36 steel, 304 and 316 stainless, 6061-T651 and MIC-6 cast aluminum.
| Thickness (in) | Decimal | mm | Nearest metric | A36 steel | 304/304L | 316/316L | 6061-T651 | MIC-6 |
|---|---|---|---|---|---|---|---|---|
| 3/16 | 0.1875 | 4.76 | 5 mm | Commonly stocked | Commonly stocked | Commonly stocked | Ask; may be a mill order | Ask; may be a mill order |
| 1/4 | 0.2500 | 6.35 | 6 mm | Commonly stocked | Commonly stocked | Commonly stocked | Commonly stocked | Commonly stocked |
| 5/16 | 0.3125 | 7.94 | 8 mm | Commonly stocked | Commonly stocked | Ask; may be a mill order | Ask; may be a mill order | Ask; may be a mill order |
| 3/8 | 0.3750 | 9.52 | 10 mm | Commonly stocked | Commonly stocked | Commonly stocked | Commonly stocked | Commonly stocked |
| 1/2 | 0.5000 | 12.70 | 12 mm | Commonly stocked | Commonly stocked | Commonly stocked | Commonly stocked | Commonly stocked |
| 5/8 | 0.6250 | 15.88 | 15 mm | Commonly stocked | Commonly stocked | Commonly stocked | Commonly stocked | Commonly stocked |
| 3/4 | 0.7500 | 19.05 | 20 mm | Commonly stocked | Commonly stocked | Commonly stocked | Commonly stocked | Commonly stocked |
| 7/8 | 0.8750 | 22.22 | 20 mm | Commonly stocked | Ask; may be a mill order | Ask; may be a mill order | Commonly stocked | Ask; may be a mill order |
| 1 | 1.0000 | 25.40 | 25 mm | Commonly stocked | Commonly stocked | Commonly stocked | Commonly stocked | Commonly stocked |
| 1-1/4 | 1.2500 | 31.75 | 30 mm | Commonly stocked | Commonly stocked | Ask; may be a mill order | Commonly stocked | Commonly stocked |
| 1-1/2 | 1.5000 | 38.10 | 40 mm | Commonly stocked | Commonly stocked | Commonly stocked | Commonly stocked | Commonly stocked |
| 1-3/4 | 1.7500 | 44.45 | 45 mm | Commonly stocked | Ask; may be a mill order | Ask; may be a mill order | Commonly stocked | Ask; may be a mill order |
| 2 | 2.0000 | 50.80 | 50 mm | Commonly stocked | Commonly stocked | Commonly stocked | Commonly stocked | Commonly stocked |
| 2-1/2 | 2.5000 | 63.50 | 60 mm | Commonly stocked | Commonly stocked | Ask; may be a mill order | Commonly stocked | Commonly stocked |
| 3 | 3.0000 | 76.20 | 80 mm | Commonly stocked | Commonly stocked | Ask; may be a mill order | Commonly stocked | Commonly stocked |
| 3-1/2 | 3.5000 | 88.90 | 90 mm | Commonly stocked | Ask; may be a mill order | Ask; may be a mill order | Commonly stocked | Ask; may be a mill order |
| 4 | 4.0000 | 101.60 | 100 mm | Commonly stocked | Ask; may be a mill order | Ask; may be a mill order | Commonly stocked | Commonly stocked |
| 5 | 5.0000 | 127.00 | 120 mm | Commonly stocked | Ask; may be a mill order | Ask; may be a mill order | Commonly stocked | Ask; may be a mill order |
| 6 | 6.0000 | 152.40 | 150 mm | Commonly stocked | Ask; may be a mill order | Ask; may be a mill order | Commonly stocked | Ask; may be a mill order |
✓ = commonly stocked by large U.S. distributors. A blank cell means ask: it may be a mill order or a specialty item, not that it does not exist. Aluminum under 0.250 in is sheet, so 6061 and MIC-6 start at 1/4 in.
A36 steel
Hot rolled carbon plate
304/304L
Hot rolled, annealed and pickled
316/316L
Hot rolled, annealed and pickled
6061-T651
Rolled aluminum plate, stress relieved by stretching
MIC-6
Cast aluminum tooling plate, machined flat
Common plate sizes
| Size (in) | Feet | mm | Typical for |
|---|---|---|---|
| 48 x 96 | 4 x 8 | 1,219 x 2,438 | Steel, stainless and aluminum plate in lighter thicknesses |
| 48 x 120 | 4 x 10 | 1,219 x 3,048 | Steel and stainless |
| 48 x 144 | 4 x 12 | 1,219 x 3,658 | Aluminum plate (6061-T651, cast tooling plate) |
| 60 x 120 | 5 x 10 | 1,524 x 3,048 | Steel and stainless; fits a 5 x 10 ft cutting table |
| 60 x 144 | 5 x 12 | 1,524 x 3,658 | Aluminum and steel |
| 72 x 144 | 6 x 12 | 1,829 x 3,658 | Aluminum and steel |
| 96 x 240 | 8 x 20 | 2,438 x 6,096 | Carbon steel (A36, A572) mill plate |
| 96 x 288 | 8 x 24 | 2,438 x 7,315 | Carbon steel mill plate |
| 120 x 240 | 10 x 20 | 3,048 x 6,096 | Carbon steel mill plate |
Metric plate is commonly 1250 x 2500, 1500 x 3000 and 2000 x 4000 mm. Estimate plate weight with the metal weight calculator.
Need plate parts cut and machined? , or browse CNC machine shops.
Buying plate cut to size
- Most plate is bought as cut pieces, not full plates. Service centers saw-cut aluminum and cast tooling plate, and cut steel with oxy-fuel, plasma, laser or waterjet. You pay for the piece plus a cut charge, which is usually cheaper than buying and storing a full plate.
- Order with cleanup stock. Saw-cut and burned blanks are usually supplied with a plus-only tolerance. Ask for the service center's figure, and add enough to square the edges if the part is machined all over.
- Thermal cuts leave a heat-affected edge. Oxy-fuel and plasma harden and scale the edge of steel plate. Machine it off where the edge is a datum or will be tapped; waterjet and saw cuts do not have this problem.
- Buy thicker when both faces are machined. Rolled plate is not flat or parallel enough to be a precision face as delivered. If both faces must be machined, start from the next standard thickness up, or use cast tooling plate that arrives flat.
- Say the temper. Call out 6061-T651, not just 6061, so the plate is the stretched, stress-relieved product. Stainless plate is usually dual-certified (304/304L, 316/316L); say which you need if it matters.
Related charts, tools and guides
Frequently asked questions
- Is 1/2 in plate exactly 0.500 in thick?
- Rarely. Hot-rolled carbon plate ordered to thickness is allowed only a small under-tolerance (0.01 in under ASTM A6) but a larger over-tolerance, so 1/2 in A36 often measures a little over. Rolled aluminum plate has its own plus-and-minus tolerance under ASTM B209. Cast tooling plate such as MIC-6 is machined to a much tighter thickness. Plan machining stock from the actual plate, not the nominal.
- What is the difference between 6061-T6 and 6061-T651 plate?
- T651 is T6 that was stretched a small controlled amount after quenching to relieve residual stress. It moves much less when you machine pockets into it. Aluminum plate is almost always sold as T651; T6 is the sheet and drawn-product temper.
- When should I use MIC-6 instead of 6061 plate?
- For fixture plates, vacuum plates, inspection bases and anything that must stay flat after heavy material removal. MIC-6 is cast and stress relieved, so it barely moves when cut, and it ships with machined faces. It is weaker than 6061-T651 and does not anodize to a cosmetic finish as well.
- Where does steel sheet end and plate begin?
- In the U.S. steel trade, 3/16 in and thicker is usually sold as plate; ASTM A6 draws the formal line by width and thickness. Aluminum becomes plate at 0.250 in.
- What metric plate matches an inch drawing?
- Use the nearest metric plate column, then check it still leaves machining stock. 1/2 in (12.7 mm) is usually bought as 12 mm only when the part is finished at or under 12 mm; otherwise buy 15 mm and face it down.
