Galvanizing & Coating Weight
Convert coating thickness to mass per area and back through the coating density — zinc, aluminium, tin — per side and both sides, plus mass on a part.
Thickness per side, g/m² per side and total, oz/ft², the coating mass per part and per batch from the part area, and the pickup as a percentage of the part mass.
Example: 20 µm of zinc (7.14 g/cm³) per side = 142.8 g/m² per side, 285.6 g/m² both sides; on a 2.5 m² part of 40 kg that is 0.71 kg of coating, a 1.8 % pickup. Z275 (137.5 g/m² per side) ≈ 19.3 µm.
Microns and grams
are the same number.
The identity behind coating weights, per-side conventions, and where the standards come in.
The identity
A coating of thickness t (µm) and density ρ (g/cm³) weighs t × ρ grams per square metre — a unit coincidence that makes the conversion trivial: zinc at 7.14 g/cm³ is 7.14 g/m² per µm, so 20 µm is 142.8 g/m². 1 oz/ft² is 305.15 g/m². The density is yours to enter (zinc 7.14, aluminium 2.70, tin 7.29 g/cm³ are physical constants).
Per side and total
Sheet coating classes such as Z275 are the total of both sides — 137.5 g/m² per side, about 19 µm. Hot-dip galvanized parts are usually quoted per side or as a minimum thickness. The page reports both, then the coating mass on a part from its coated area and the pickup as a percentage of the bare mass — useful for shipping weights and for the zinc bill.
Standards and alloys
Minimum coatings by class and by steel thickness are set by EN 10346, ISO 1461, ASTM A123 and their relatives — labelled here, not reproduced. Real hot-dip coatings contain zinc-iron alloy layers a little denser than pure zinc, so measured thickness and weighed mass differ by a few percent. Nothing leaves the browser; the same four anonymous usage counts as the rest of the site apply.
SOURCES
- g/m² = µm × density (g/cm³); 1 oz/ft² = 305.15 g/m²; coating density entered by the user (zinc 7.14 g/cm³); coating classes are the standard’s (EN 10346, ISO 1461, ASTM A123 — labelled only)
Last reviewed 21 September 2026. How results are checked: How we verify.