Sheet Metal Gauge Converter — Gauge to Thickness in mm and inch

Real-world use cases

• Order the right ductwork and HVAC sheet

  The job spec calls for 24 gauge galvanized for residential supply runs and 18 gauge for larger trunks. Pick galvanized, read that 24 gauge is about 0.7 mm and 18 gauge is about 1.31 mm, and you can confirm the supplier shipped the right coil before the brake bends a hundred fittings in the wrong thickness.

• Read a fabrication drawing that only says a number

  A drawing reads simply 16 ga with no material noted. Check it against both tables: 16 ga carbon steel is 1.519 mm, 16 ga stainless is 1.588 mm, 16 ga aluminum is 1.291 mm. Now you can ask the right question before cutting instead of guessing and scrapping a sheet.

• Match a measured part back to a stock gauge

  A customer brings in a bracket to copy. Caliper it at 1.2 mm, switch to thickness-to-gauge, choose steel, and the tool returns 18 gauge as the closest stock size. Now you can quote the job from a standard coil rather than special-ordering an odd thickness.

• Convert imperial gauge specs to metric for an overseas shop

  A US drawing lists 20 gauge steel and your shop works in mm. The tool gives 0.912 mm, which you can hand to the laser operator and the material buyer directly. The shareable link sends the exact material and gauge so nobody re-types the spec and slips a decimal.

Common pitfalls

• Reading a gauge number without checking the material. 16 ga is 1.519 mm in steel but 1.291 mm in aluminum. A spec that just says 16 ga is ambiguous, so confirm carbon steel, stainless or aluminum before you order or bend.

• Assuming a bigger gauge number is thicker. The scale runs backwards, so 7 ga is heavy 4.5 mm plate while 30 ga is 0.3 mm foil. Going from 20 ga to 16 ga makes the sheet thicker, not thinner, which catches people sizing for strength.

• Treating gauge as an exact measurement. Gauge is a nominal trade size and real sheets vary by rolling tolerance and coating. A 16 ga sheet measured with calipers may read a few hundredths off, so measure rather than assume when a tight fit matters.

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