{
 "meta": {
  "title": "Sheet Metal Gauge Chart",
  "rows": 24,
  "sources": {
   "steel": "Manufacturers' Standard Gauge for Sheet Steel (MSG)",
   "galvanized": "ASTM A653 galvanized sheet gauge table (coating class not asserted - see note)",
   "stainless": "ASTM A480",
   "aluminum": "Brown & Sharpe / AWG \u2014 computed from d = 0.005 x 92^((36-n)/39)"
  },
  "derived": "mm and lb/ft^2 computed from thickness x density (steel .2836, stainless .2894, aluminum .0975 lb/in^3)",
  "key_insight": "Aluminum sheet gauge IS the AWG system and can be computed exactly; steel/stainless gauges are separate weight-based standards that must be looked up.",
  "zinc_coating": {
   "min_in": 0.0037,
   "max_in": 0.0038,
   "note": "Galvanized runs a consistent ~0.0037 in thicker than bare steel across gauges 8-30. That is about 2.3x a G90 coating (0.90 oz/ft2 two-sided is roughly 0.0016 in), so the difference is not attributable to G90 alone - treat it as the published galvanized gauge value, not as base steel plus a known coating class."
  },
  "verification": "Aluminum published-vs-computed max deviation 0.184%"
 },
 "columns": [
  "gauge",
  "steel_in",
  "galvanized_in",
  "stainless_in",
  "aluminum_in",
  "zinc_coating_in",
  "steel_lb_per_sqft"
 ],
 "rows": [
  {
   "gauge": 7,
   "steel_in": 0.1793,
   "galvanized_in": null,
   "stainless_in": 0.1875,
   "aluminum_in": 0.1443,
   "zinc_coating_in": null,
   "steel_lb_per_sqft": 7.322
  },
  {
   "gauge": 8,
   "steel_in": 0.1644,
   "galvanized_in": 0.1681,
   "stainless_in": 0.1719,
   "aluminum_in": 0.1285,
   "zinc_coating_in": 0.0037,
   "steel_lb_per_sqft": 6.714
  },
  {
   "gauge": 9,
   "steel_in": 0.1495,
   "galvanized_in": 0.1532,
   "stainless_in": 0.1563,
   "aluminum_in": 0.1144,
   "zinc_coating_in": 0.0037,
   "steel_lb_per_sqft": 6.105
  },
  {
   "gauge": 10,
   "steel_in": 0.1345,
   "galvanized_in": 0.1382,
   "stainless_in": 0.1406,
   "aluminum_in": 0.1019,
   "zinc_coating_in": 0.0037,
   "steel_lb_per_sqft": 5.493
  },
  {
   "gauge": 11,
   "steel_in": 0.1196,
   "galvanized_in": 0.1233,
   "stainless_in": 0.125,
   "aluminum_in": 0.0907,
   "zinc_coating_in": 0.0037,
   "steel_lb_per_sqft": 4.884
  },
  {
   "gauge": 12,
   "steel_in": 0.1046,
   "galvanized_in": 0.1084,
   "stainless_in": 0.1094,
   "aluminum_in": 0.0808,
   "zinc_coating_in": 0.0038,
   "steel_lb_per_sqft": 4.272
  },
  {
   "gauge": 13,
   "steel_in": 0.0897,
   "galvanized_in": 0.0934,
   "stainless_in": 0.0938,
   "aluminum_in": 0.072,
   "zinc_coating_in": 0.0037,
   "steel_lb_per_sqft": 3.663
  },
  {
   "gauge": 14,
   "steel_in": 0.0747,
   "galvanized_in": 0.0785,
   "stainless_in": 0.0781,
   "aluminum_in": 0.0641,
   "zinc_coating_in": 0.0038,
   "steel_lb_per_sqft": 3.051
  },
  {
   "gauge": 15,
   "steel_in": 0.0673,
   "galvanized_in": 0.071,
   "stainless_in": 0.0703,
   "aluminum_in": 0.0571,
   "zinc_coating_in": 0.0037,
   "steel_lb_per_sqft": 2.748
  },
  {
   "gauge": 16,
   "steel_in": 0.0598,
   "galvanized_in": 0.0635,
   "stainless_in": 0.0625,
   "aluminum_in": 0.0508,
   "zinc_coating_in": 0.0037,
   "steel_lb_per_sqft": 2.442
  },
  {
   "gauge": 17,
   "steel_in": 0.0538,
   "galvanized_in": 0.0575,
   "stainless_in": 0.0563,
   "aluminum_in": 0.0453,
   "zinc_coating_in": 0.0037,
   "steel_lb_per_sqft": 2.197
  },
  {
   "gauge": 18,
   "steel_in": 0.0478,
   "galvanized_in": 0.0516,
   "stainless_in": 0.05,
   "aluminum_in": 0.0403,
   "zinc_coating_in": 0.0038,
   "steel_lb_per_sqft": 1.952
  },
  {
   "gauge": 19,
   "steel_in": 0.0418,
   "galvanized_in": 0.0456,
   "stainless_in": 0.0438,
   "aluminum_in": 0.0359,
   "zinc_coating_in": 0.0038,
   "steel_lb_per_sqft": 1.707
  },
  {
   "gauge": 20,
   "steel_in": 0.0359,
   "galvanized_in": 0.0396,
   "stainless_in": 0.0375,
   "aluminum_in": 0.032,
   "zinc_coating_in": 0.0037,
   "steel_lb_per_sqft": 1.466
  },
  {
   "gauge": 21,
   "steel_in": 0.0329,
   "galvanized_in": 0.0366,
   "stainless_in": 0.0344,
   "aluminum_in": 0.0285,
   "zinc_coating_in": 0.0037,
   "steel_lb_per_sqft": 1.344
  },
  {
   "gauge": 22,
   "steel_in": 0.0299,
   "galvanized_in": 0.0336,
   "stainless_in": 0.0313,
   "aluminum_in": 0.0253,
   "zinc_coating_in": 0.0037,
   "steel_lb_per_sqft": 1.221
  },
  {
   "gauge": 23,
   "steel_in": 0.0269,
   "galvanized_in": 0.0306,
   "stainless_in": 0.0281,
   "aluminum_in": 0.0226,
   "zinc_coating_in": 0.0037,
   "steel_lb_per_sqft": 1.099
  },
  {
   "gauge": 24,
   "steel_in": 0.0239,
   "galvanized_in": 0.0276,
   "stainless_in": 0.025,
   "aluminum_in": 0.0201,
   "zinc_coating_in": 0.0037,
   "steel_lb_per_sqft": 0.976
  },
  {
   "gauge": 25,
   "steel_in": 0.0209,
   "galvanized_in": 0.0247,
   "stainless_in": 0.0219,
   "aluminum_in": 0.0179,
   "zinc_coating_in": 0.0038,
   "steel_lb_per_sqft": 0.854
  },
  {
   "gauge": 26,
   "steel_in": 0.0179,
   "galvanized_in": 0.0217,
   "stainless_in": 0.0188,
   "aluminum_in": 0.0159,
   "zinc_coating_in": 0.0038,
   "steel_lb_per_sqft": 0.731
  },
  {
   "gauge": 27,
   "steel_in": 0.0164,
   "galvanized_in": 0.0202,
   "stainless_in": 0.0172,
   "aluminum_in": 0.0142,
   "zinc_coating_in": 0.0038,
   "steel_lb_per_sqft": 0.67
  },
  {
   "gauge": 28,
   "steel_in": 0.0149,
   "galvanized_in": 0.0187,
   "stainless_in": 0.0156,
   "aluminum_in": 0.0126,
   "zinc_coating_in": 0.0038,
   "steel_lb_per_sqft": 0.608
  },
  {
   "gauge": 29,
   "steel_in": 0.0135,
   "galvanized_in": 0.0172,
   "stainless_in": 0.0141,
   "aluminum_in": 0.0113,
   "zinc_coating_in": 0.0037,
   "steel_lb_per_sqft": 0.551
  },
  {
   "gauge": 30,
   "steel_in": 0.012,
   "galvanized_in": 0.0157,
   "stainless_in": 0.0125,
   "aluminum_in": 0.01,
   "zinc_coating_in": 0.0037,
   "steel_lb_per_sqft": 0.49
  }
 ]
}