Aluminum is sold by weight but specified by dimensions, and the number that connects the two is density. This page is the aluminum density table by alloy, so you can convert a millimeter of thickness into a kilogram per square metre for the exact grade you are ordering.
The planning figure everyone uses is 2.70 g/cm³ — close enough for estimates. But the actual density ranges from 2.66 to 2.81 g/cm³ depending on the alloying elements, and on a full container the difference is hundreds of kilograms.
Density by alloy
| Grade | Density (g/cm³) | Weight of 1 mm sheet (kg/m²) |
|---|---|---|
| 1050 | 2.71 | 2.71 |
| 1060 | 2.71 | 2.71 |
| 1100 | 2.71 | 2.71 |
| 1235 | 2.71 | 2.71 |
| 3003 | 2.73 | 2.73 |
| 3004 | 2.72 | 2.72 |
| 3105 | 2.72 | 2.72 |
| 5052 | 2.68 | 2.68 |
| 5083 | 2.66 | 2.66 |
| 5754 | 2.67 | 2.67 |
| 6061 | 2.70 | 2.70 |
| 6082 | 2.70 | 2.70 |
| 6063 | 2.70 | 2.70 |
| 7075 | 2.81 | 2.81 |
| 8011 | 2.71 | 2.71 |
The rule that explains the pattern: magnesium lightens, zinc and copper densify. The 5xxx magnesium grades are the lightest (5083 at 2.66); the pure 1xxx grades sit at 2.71; the 7xxx zinc grades are the heaviest (7075 at 2.81). The weight of a 1 mm sheet per square metre is simply the density number, because 1 mm × 1 m² = 1,000 cm³, and at a density of d g/cm³ that is d kilograms.
These are the same densities the weight calculator uses, kept identical across the site so a given grade never shows two different densities.
Why density matters in practice
The density spread looks small — 2.66 to 2.81 is about 5.5% — but it compounds in three places:
- Freight. A 20-tonne order of 7075 has a different physical volume than a 20-tonne order of 5083, and on a container that can be the difference between one box and two.
- Crane and handling limits. A plate or a forged part is lifted by weight; getting the density wrong by a grade can over- or under-load a lift plan.
- Costing by area. If a buyer converts a per-square-metre price to a per-kilo price using 2.70 for a 5083 order, the figures drift by over 1%, which is real money on a container.
Density versus specific gravity
The two terms are often used interchangeably, and for aluminum they are nearly the same number. Specific gravity is the ratio of the material's density to the density of water (1.0 g/cm³), so it is unitless and numerically equal to the density in g/cm³. A 6061 part has a specific gravity of about 2.70, meaning it is 2.70 times as dense as water.
The useful comparison is against steel: aluminum is roughly one-third the density of steel (7.85 g/cm³), which is the entire reason aluminum is the lightweight structural metal. That ratio — about 2.70 against 7.85 — is worth remembering, because it is the answer to "how much weight do I save going to aluminum."
The weight formula, per alloy
With the density in hand, the weight formulas are exact:
- Sheet and plate: weight (kg) = length (m) × width (m) × thickness (mm) × density
- Per square metre: weight (kg/m²) = thickness (mm) × density
- Round bar: weight (kg/m) = π/4 × diameter² (mm) × density / 1000
- Coil: weight (kg) = π/4 × (OD² − ID²) (mm) × width (m) × density / 1000
A 3 mm × 1,500 × 3,000 mm 5052 sheet: 1.5 × 3.0 × 3 × 2.68 = 36.18 kg. The same sheet in 7075: 1.5 × 3.0 × 3 × 2.81 = 37.94 kg — about 1.8 kg heavier, purely from density.
The checksum
Before you commit a weight to a freight quote or a lift plan, confirm which grade the order is, and use that grade's density rather than the 2.70 planning figure. The difference is small per sheet and material on a full order.
The density for every grade is stated on its alloy reference page, and the weight calculator applies the correct density automatically once you pick the alloy. If you want a tonnage checked against the dimensions, send the line items — getting the grade's density right is what turns the estimate into an exact number.