Aluminum Weight by Shape and Alloy: Plate, Bar, Tube, and Sheet Reference
Reviewed by Jerry Croteau, Founder & Editor
Table of Contents
Aluminum is roughly one-third the weight of steel — 2.71 g/cm3 vs 7.85 g/cm3 — which is why it dominates weight-sensitive applications: aircraft, marine, automotive, bicycle frames, and aerospace structures. But "aluminum" covers hundreds of alloys. For most practical purposes the density variation between alloys is small (under 5%), but the alloy determines machinability, weldability, and corrosion resistance as much as weight.
Our handles plate, sheet, bar, tube, and pipe. This guide covers the density by alloy and reference weights for common products.
Alloy series overview
| Series | Primary element | Key use |
|---|---|---|
| 1xxx | Pure aluminum | Electrical conductors, chemical equipment |
| 2xxx | Copper | Aerospace structural (2024) |
| 3xxx | Manganese | Cookware, roofing, sheet (3003) |
| 5xxx | Magnesium | Marine, automotive (5052, 5083) |
| 6xxx | Magnesium + Silicon | General structural, extrusions (6061, 6063) |
| 7xxx | Zinc | Highest strength aerospace (7075) |
Density by alloy
| Alloy | lbs/in3 | g/cm3 |
|---|---|---|
| 1100 | 0.0975 | 2.70 |
| 2024 | 0.1000 | 2.78 |
| 3003 | 0.0990 | 2.73 |
| 5052 | 0.0970 | 2.68 |
| 6061 | 0.0980 | 2.70 |
| 7075 | 0.1010 | 2.81 |
Use 0.098 lbs/in3 as a universal value for quick estimates — the error is under 3% for any common alloy.
Sheet and plate weights (4x8 ft = 48" x 96")
| Thickness | Weight per 4x8 sheet |
|---|---|
| 0.040" (18 gauge) | 18.1 lbs |
| 0.063" (16 gauge) | 28.5 lbs |
| 0.125" (1/8") | 56.7 lbs |
| 0.250" (1/4") | 113.4 lbs |
| 0.375" (3/8") | 170.1 lbs |
| 0.500" (1/2") | 226.9 lbs |
Round bar weight per foot
Formula: W = 0.2904 x d2 lbs/ft (d = diameter in inches)
| Diameter | lbs/ft |
|---|---|
| 1/4" | 0.072 |
| 1/2" | 0.291 |
| 3/4" | 0.654 |
| 1" | 1.163 |
| 1-1/2" | 2.617 |
| 2" | 4.653 |
Aluminum vs steel for the same part
The density ratio is 2.71 / 7.85 = 0.345. Any aluminum part is 34.5% the weight of the identical steel part. This holds for any shape.
| Part | Steel weight | Aluminum weight | Savings |
|---|---|---|---|
| 1" round bar, 10 ft | 26.7 lbs | 9.7 lbs | 64% |
| 1/4" plate, 4x8 ft | 326 lbs | 113 lbs | 65% |
The engineering tradeoff: for the same cross-section, aluminum is lighter but less stiff. Young's modulus of aluminum is about 10,000 ksi vs 29,000 ksi for steel. To match steel stiffness, aluminum sections must be geometrically larger — partially offsetting the weight savings in bending applications.
For any shape, alloy, and quantity, the gives accurate results. For other metals, the covers steel, copper, brass, titanium, and 90+ materials.
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