Reference
Sheet metal gauge chart
Gauge to inch and millimeter for carbon steel, stainless, and aluminum. The catch most engineers hit: the same gauge number is a different thickness in each material.
A sheet metal gauge chart converts a gauge number into the actual material thickness it represents. Gauge is a legacy shorthand for thickness: the higher the gauge number, the thinner the sheet. The complication — and the reason this page exists — is that carbon steel, stainless steel, and aluminum each use a different gauge standard, so a single gauge number maps to three different thicknesses depending on the metal.
Gauge, inch, and millimeter by material
Read across each row to compare the same gauge number in each material. Values are the nominal decimal thickness followed by the millimeter equivalent (inch / mm).
| Gauge | Carbon steel (MSG) | Stainless steel | Aluminum (AWG) |
|---|---|---|---|
| 7 | 0.1793 / 4.554 | 0.1875 / 4.763 | 0.1443 / 3.665 |
| 8 | 0.1644 / 4.176 | 0.1719 / 4.366 | 0.1285 / 3.264 |
| 9 | 0.1495 / 3.797 | 0.1563 / 3.969 | 0.1144 / 2.906 |
| 10 | 0.1345 / 3.416 | 0.1406 / 3.571 | 0.1019 / 2.588 |
| 11 | 0.1196 / 3.038 | 0.1250 / 3.175 | 0.0907 / 2.304 |
| 12 | 0.1046 / 2.657 | 0.1094 / 2.779 | 0.0808 / 2.052 |
| 13 | 0.0897 / 2.278 | 0.0938 / 2.383 | 0.0720 / 1.829 |
| 14 | 0.0747 / 1.897 | 0.0781 / 1.984 | 0.0641 / 1.628 |
| 15 | 0.0673 / 1.709 | 0.0703 / 1.786 | 0.0571 / 1.450 |
| 16 | 0.0598 / 1.519 | 0.0625 / 1.588 | 0.0508 / 1.290 |
| 18 | 0.0478 / 1.214 | 0.0500 / 1.270 | 0.0403 / 1.024 |
| 20 | 0.0359 / 0.912 | 0.0375 / 0.953 | 0.0320 / 0.813 |
| 22 | 0.0299 / 0.759 | 0.0313 / 0.795 | 0.0253 / 0.643 |
| 24 | 0.0239 / 0.607 | 0.0250 / 0.635 | 0.0201 / 0.511 |
| 26 | 0.0179 / 0.455 | 0.0188 / 0.478 | 0.0159 / 0.404 |
Source: carbon steel per the Manufacturers’ Standard Gauge for sheet steel (MSG, 41.82 lb/ft² per inch); stainless steel per standard mill gauge practice for 300-series sheet; aluminum per the American Wire Gauge (AWG / Brown & Sharpe). Values are nominal — mill tolerance applies, and galvanized stock runs slightly thicker than the bare-steel value by the weight of its coating. Verify critical dimensions against your material certification and drawing.
How to read the chart
Find your gauge in the left column, then read across to your material. If your print calls out “16 ga” with no material, it is ambiguous by 0.012 in (0.3 mm) across the three columns — enough to matter for a press fit, a stack-up, or a bend deduction. The fix is to specify the decimal thickness as the controlling dimension and let the gauge number ride along as a reference only.
Common mistakes
- Assuming gauge is universal. The single most common error. 16 gauge is 1.519 mm in steel but 1.290 mm in aluminum. Always pair a gauge number with its material.
- Forgetting the coating. Galvanized and pre-painted stock is thicker than its base gauge. If a fit is tight, dimension over the coating.
- Sorting by gauge instead of thickness. Because the three standards interleave, a “heavier gauge number” in one material can be thinner than a lighter number in another. Compare decimals, not gauge labels.
- Ignoring mill tolerance. Gauge is nominal. Cold-rolled sheet carries its own thickness tolerance per ASTM; design your critical stack-ups with that band in mind.
Where this fits our shop
Nevatronix Sheet Metal works from 0.02 in to 0.50 in (0.5–12.7 mm) on sheet up to 60 in × 120 in, across aluminum, carbon steel, cold-rolled steel, stainless, copper, and coated steel. Once you know your thickness, the next design question is usually the bend — see the bend radius chart for the minimum inside radius your gauge and material can take, and press brake forming for how we hold the bend.
Frequently asked questions
- Is a 16 gauge steel part the same thickness as 16 gauge aluminum?
- No. A gauge number is not a universal thickness — each material family uses a different underlying gauge standard. 16 gauge is 0.0598 in (1.519 mm) in carbon steel, 0.0625 in (1.588 mm) in stainless, and 0.0508 in (1.290 mm) in aluminum. That is why you should always state the decimal thickness (or the gauge and the material together) on a drawing, never the gauge number alone.
- What gauge standard does mild steel use?
- Carbon and mild sheet steel use the Manufacturers’ Standard Gauge (MSG), which is defined by weight: 41.82 lb per square foot per inch of thickness. So 16 ga (2.5 lb/ft²) works out to 0.0598 in. Galvanized steel is slightly thicker than the bare-steel value because the zinc coating adds thickness on top of the base gauge.
- Why does aluminum use different gauge numbers than steel?
- Aluminum sheet follows the American Wire Gauge (AWG), also called the Brown & Sharpe gauge, which is a geometric series unrelated to the weight-based steel standard. The two systems simply disagree, so the same gauge number lands at a different thickness. Most aluminum drawings avoid the ambiguity by calling out the decimal thickness directly.
- What thickness range can Nevatronix Sheet Metal work?
- Our documented working range is 0.02 in to 0.50 in (0.5 mm to 12.7 mm) across aluminum, carbon steel, stainless, copper, and coated steel, on sheet up to 60 in × 120 in. Most enclosure and bracket work lands between 20 ga and 10 ga; heavier plate up to 1/2 in is handled through shearing and plate roll forming. Send the decimal thickness on the print and we quote against it.
- Should I put the gauge number or the decimal thickness on my drawing?
- Put the decimal thickness as the controlling dimension and treat the gauge number as a reference. Gauge numbers are ambiguous across materials and carry a mill tolerance of their own, so a decimal callout with the material grade removes any question about what stock is ordered and cut. If you specify a gauge, always pair it with the material.
Have the thickness? Get it quoted.
Send a STEP or DXF with the material grade and decimal thickness. We confirm the stock, the bend, and the ship date — most parts turn a quote within a business day.