About

Miscalculating aluminum stock weight leads to structural under-specification or wasted procurement budget. A 1mm wall-thickness error on a 6m rectangular tube of alloy 6061 (density 2.71 g/cm³) compounds into kilograms of deviation across a production run. This calculator applies the fundamental relation W = V × ρ for 12 standard cross-section profiles and 15 alloy grades with published densities per ASTM B209/B221. It assumes homogeneous material with no voids, mill tolerance of 0, and room-temperature density. For critical aerospace or marine applications, verify against certified mill test reports.

Formulas

The weight of any aluminum profile is derived from the cross-sectional area multiplied by the extrusion length and the alloy density.

W = A × L × ρ

Where W = weight in g, A = cross-sectional area in mm², L = length in mm, and ρ = density in g/mm³.

Cross-sectional area formulas by shape:

Round Bar: A = π4 × d²

Round Tube: A = π4 × (D² − d²)

Hex Bar: A = 3√32 × s²

Where d = diameter or inner diameter, D = outer diameter, s = flat-to-flat distance for hex, and wall thickness t is used for hollow sections. The result is divided by 1000 to convert grams to kilograms.

Reference Data

Alloy	Series	Density g/cm³	Typical Use	Temper
1100	1xxx	2.71	Chemical equipment, food packaging	O, H14
2011	2xxx	2.83	Screw machine products	T3, T8
2014	2xxx	2.80	Aircraft structures, truck frames	T4, T6
2024	2xxx	2.78	Aircraft skins, rivets	T3, T4
3003	3xxx	2.73	Heat exchangers, cooking utensils	O, H14
5052	5xxx	2.68	Marine, pressure vessels	O, H32
5083	5xxx	2.66	Shipbuilding, cryogenics	O, H116
5086	5xxx	2.66	Marine, unfired pressure vessels	O, H34
6061	6xxx	2.71	Structural, automotive, marine	T4, T6
6063	6xxx	2.70	Architectural extrusions	T5, T6
6082	6xxx	2.71	Bridges, cranes, structural	T6
7005	7xxx	2.78	Bicycle frames, railway stock	T53
7050	7xxx	2.83	Aerospace plate & forgings	T7451
7075	7xxx	2.81	Aerospace, high-stress parts	T6, T651
8011	8xxx	2.71	Foil, bottle caps, heat exchangers	O, H18

Frequently Asked Questions

Suppliers typically quote theoretical weight based on nominal dimensions. Mill tolerances per ASTM B221 allow wall thickness variation of ±10% for extruded profiles. Additionally, supplier weights may include a density rounded to 2.70 g/cm³ regardless of alloy. This calculator uses alloy-specific densities from published material datasheets. For critical orders, request certified mill test reports with actual measured weights.

Published densities are at room temperature (~20 °C). Aluminum's volumetric thermal expansion coefficient is approximately 69 × 10⁻⁶ /°C. At 200 °C, density decreases by roughly 1.4%. For cryogenic applications (e.g., 5083 at −196 °C), density increases by about 0.9%. This calculator assumes room-temperature density. For extreme-temperature structural analysis, apply the thermal correction factor manually.

Alloy 6061 has a density of 2.71 g/cm³ while 7075 is 2.81 g/cm³ - a 3.7% increase in weight per unit volume. A 1-meter length of 50 mm round bar in 6061 weighs approximately 5.33 kg versus 5.52 kg in 7075. The choice between them is driven by strength-to-weight ratio requirements: 7075-T6 yields ~503 MPa versus ~276 MPa for 6061-T6, so you can often use thinner 7075 sections, offsetting the higher density.

Cast alloys (e.g., A356, A380) have different densities than wrought alloys due to porosity and different alloying elements. A356 casting density is approximately 2.67 g/cm³ while A380 die-cast is about 2.71 g/cm³. This calculator focuses on wrought alloy extrusions and mill products. For castings, use the casting-specific density and be aware that internal porosity can reduce actual density by 1-3% compared to theoretical values.

For custom profiles not covered by the 12 standard shapes, calculate the cross-sectional area from your CAD drawing in mm², then use the Sheet/Plate mode: enter width equal to your area value, thickness as 1 mm, and length as your piece length. The formula W = A × L × ρ applies universally. Alternatively, decompose a complex profile into rectangles and subtract hollow areas manually.

Type II anodizing produces an oxide layer of 5-25 µm. Aluminum oxide (Al₂O₃) has a density of 3.95 g/cm³ versus ~2.71 g/cm³ for the base metal. However, approximately half the oxide layer grows inward (replacing aluminum) and half outward. Net weight increase is typically under 0.1% for standard anodizing. Hard anodize (Type III, 25-75 µm) may add up to 0.3%. This calculator does not account for surface treatments.