Comparing steel, aluminum, and stainless sheet starts with density and ends with how you specify thickness. Two blanks with identical length and width can differ sharply in mass because alloying elements change kg/m³. Gauge numbering adds a second layer: the same gauge label does not imply the same thickness across metals. Use this comparison alongside the sheet metal weight calculator to preview how material choice shifts weight before you update a BOM or freight estimate.

Typical densities in SheetMetalCalc

The calculator’s default reference densities (not alloy-specific certifications) are:

• Mild steel: 7850 kg/m³
• Stainless steel: 8000 kg/m³ (common 304-family reference)
• Aluminum: 2700 kg/m³ (wrought alloy reference)

Galvanized steel uses the same substrate density as carbon steel in the tool; coating mass is not added. Copper and brass are available separately when you need them.

Same size blank, different mass

Consider a flat sheet 1 m × 1 m × 1 mm thick, quantity 1:

• Mild steel: 0.001 m³ × 7850 ≈ 7.85 kg
• Stainless: 0.001 m³ × 8000 ≈ 8.00 kg
• Aluminum: 0.001 m³ × 2700 ≈ 2.70 kg

Aluminum is roughly one-third the mass of steel at the same rectangular volume. Stainless is slightly heavier than mild steel for the same dimensions because of higher typical density.

Gauge behavior differs

If a drawing lists “16 ga” without material context, do not assume a single thickness. The calculator’s stainless gauge table and mild steel MSG-style table resolve different mm values at the same integer. For aluminum, another chart applies. When comparing alternates, either:

• Normalize to a measured thickness in mm, or
• Run three calculator scenarios with the correct material selected for each.

The gauge chart guide covers table sources in more detail.

Choosing material for weight-driven decisions

When steel is heavier but familiar

Carbon steel is common for fabricated enclosures and structural sheet. Weight estimates track well with handbook density if grade is plain carbon. Verify grade for specialized steels.

When aluminum wins on mass

Aluminum sheet is attractive when lift ergonomics, vehicle payload, or shipping cost dominate. Remember that gauge tables and thickness tolerances are not shared with steel. Always select Aluminum in the calculator before using gauge mode.

When stainless is specified for environment

Stainless is often chosen for corrosion resistance, not because it is light. Density is slightly above mild steel; gauge tables follow stainless chart values, not carbon steel MSG.

Using custom density

303 vs 316 stainless, or 5xxx vs 6xxx aluminum, can shift density by a few percent. Enable Use custom density when the mill sheet lists a specific value in kg/m³ or g/cm³.

Related guides

• Sheet Metal Weight Calculation Guide
• How to Calculate Sheet Metal Weight

FAQ

Why is galvanized steel the same density as mild steel?

The plugin models the steel substrate. Zinc coating adds only a small surface mass not broken out separately. That is fine for rough estimates, not for coating-certified weight.

Is stainless always 8000 kg/m³?

It is a typical 304-type reference in the tool. Use custom density for your grade when it matters.

Can I compare lb outputs?

Yes. Results include total and per-sheet lb converted from kg with standard constants.