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? Browse U.S. machine shops, or send the drawing for quotes.
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.
