Converter
Convert coating mass per area, not steel sheet weight or coating thickness. If your input is the total coating on both sides per unit sheet area, the output retains that same basis. If your input is for one side, the output is also for one side. Switching direction converts the entered value so it continues to describe the same coating mass.
Conversion formula
The factor is calculated from 1 oz = 28.349523125 g and 1 ft = 0.3048 m, using the exact mass and length definitions listed in NIST’s conversion reference . The calculation uses the full factor; results display four decimal places.
Worked example: 275 g/m² converts to 0.9012 oz/ft². Conversely, 0.90 oz/ft² converts to 274.6366 g/m². These numerical conversions do not establish compliance with a different coating specification.
Common coating designation reference
Different standards use different designation systems. The rows below retain their stated standard and native unit; they are not an equivalence table. The same letter prefix does not identify a standard by itself.
| Designation | System in this reference | Coating mass reference | Basis |
|---|---|---|---|
| Z100 | EN 10346 producer reference | 100 g/m² | Double-sided coating mass |
| Z120 | ASTM A653/A653M · SI | 120 g/m² | Minimum triple-spot average, total both sides |
| Z180 | ASTM A653/A653M · SI | 180 g/m² | Minimum triple-spot average, total both sides |
| Z275 | ASTM A653/A653M · SI | 275 g/m² | Minimum triple-spot average, total both sides |
| Z275 | EN 10346 producer reference | 275 g/m² | Double-sided coating mass |
| G30 | ASTM A653/A653M · inch-pound | 0.30 oz/ft² | Minimum triple-spot average, total both sides |
| G40 | ASTM A653/A653M · inch-pound | 0.40 oz/ft² | Minimum triple-spot average, total both sides |
| G60 | ASTM A653/A653M · inch-pound | 0.60 oz/ft² | Minimum triple-spot average, total both sides |
| G90 | ASTM A653/A653M · inch-pound | 0.90 oz/ft² | Minimum triple-spot average, total both sides |
Scroll within the table to see all columns →
ASTM rows follow Table 1 of GalvInfoNote 2.5, revision 1.2 (December 2017) . EN rows follow ArcelorMittal’s E20 hot-dip galvanized product reference . These public references are not substitutes for the edition specified on an order.
How to read a galvanized steel specification
A coating designation is one field in a specification. Also identify the standard and edition, steel grade, test basis, surface treatment and thickness basis. Confirm single-spot and per-side requirements in the governing specification; an average both-side value does not describe every spot on either face.
G90 and Z275 are a common approximate comparison, but the unit conversion above is not exactly 275 g/m². Do not infer interchangeability across ASTM and EN, or compliance with one from a label under another. Check the actual order and certificate.
Coating mass versus coating thickness
Coating mass counts material per area. Thickness measures a distance. To infer thickness you also need the coating density and the allocation to each face. If both sides receive equal mass, each side has half the total; equal allocation must not be assumed for a differential coating.
For a known single-side coating, thickness in micrometres = coating mass in g/m² ÷ coating density in g/cm³. This is a uniform-layer estimate. Surface texture and coating composition limit the inference, so this page does not convert a designation into a guaranteed single-side thickness.
The g/m² ↔ oz/ft² unit conversion works for other coatings too, but zinc designation and thickness assumptions must not be applied to 55% Al-Zn, Zn-Al-Mg or organic paint systems.
FAQ
Is G90 exactly the same as Z275?
No. They are commonly compared mass levels, but conversion of 0.90 oz/ft² is about 274.6366 g/m². Read the standard, test basis and edition attached to each designation.
Does 275 g/m² mean 275 g/m² on each side?
Not when the reference says total both sides. In that case it is the combined coating mass per unit sheet area. The distribution between sides must be checked separately.
Can I use these Z and G rows for Galvalume?
No. The listed rows describe zinc-coated sheet. Galvalume has an aluminum-zinc coating and its own applicable designation system. Only the physical unit conversion carries over.
Does zero mean the sheet meets a coating designation?
No. Zero is a valid unit-conversion input, but it makes no claim of coating or specification compliance.
Related coating and weight references
Read the galvanized steel overview and galvanizing process guide for zinc-coated sheet. Compare Galvalume steel and PPGI / PPGL paint systems when a different metallic coating or paint layer is present. The Zn-Al-Mg coating guide describes another coating family. Estimate base-metal mass with the Steel Plate & Sheet Weight Calculator , or return to Steel Tools .