Making sense of wire gauge tool markings

[piguy101]

I am looking at one of these circular tools to measure wire gauge. https://www.ebay.com/itm/Stainless-Steel-1-36-Round-AWG-SWG-Wire-Ruler-Gauge-Diameter-Measurer-Tool-J/401465997099?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

However, I cannot determine what the marking means from the picture. Is it AWG, SWG?

Also, the back side of the tool has corresponding markings. For example, gauge 0 wire is marked as .3125. What does this mean?

Thanks

[Bratster]

I'm pretty sure that's a tool for measuring sheet metal thickness, with one side being the thickness represented as gauge, and the other side is in inches.

I think the seller just has a bunch of generic terms.

The distance being measured is between the two flat parts, not the hole.

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[mmagin]

That's definitely sheet metal gauge:
https://en.wikipedia.org/wiki/Sheet_metal#Gauge
compare with https://en.wikipedia.org/wiki/American_wire_gauge#Tables_of_AWG_wire_sizes

Aren't standards wonderful?

If you're not needing to measure wire quickly, I'd just get yourself a decent caliper and look up in a table.  Soon you'll find yourself measuring everything with calipers and wondering how you ever lived without them

[Jwillis]

One side is equivalent inch scale of the other side SWG (Standard wire Gauge) scale.AWG is not interchangeable with SWG.Why they put AWG in the description is unknown. For example AWG 36 =0.00500 inches where as SWG 36 =0.007
The image below is a sheet metal gauge

[piguy101]

Thanks all! It definitely must be sheet metal gauge, which is disappointing to me. I can go with calipers for measuring the wire diameter then.

[Cerebus]

That's definitely sheet metal gauge:
https://en.wikipedia.org/wiki/Sheet_metal#Gauge
compare with https://en.wikipedia.org/wiki/American_wire_gauge#Tables_of_AWG_wire_sizes

Aren't standards wonderful?

If you're not needing to measure wire quickly, I'd just get yourself a decent caliper and look up in a table.  Soon you'll find yourself measuring everything with calipers and wondering how you ever lived without them

It's neither really.

It's in the right form for a wire gauge (you put a wire through a hole and try and pull it out through the slot, when it just pulls out that's the right size) but its got the wrong numbers. It's marked in US sheet metal gauge, not a wire gauge like AWG or SWG (the obsolete Standard Wire Gauge BS 3737:1964, which is the old Imperial British sizing, now metricated).

SWG is not the same as American sheet metal gauge, it's close-ish, but it's not the same, I mistake I see repeated regularly. Because of the huge confusion that abounds between all the different gauge systems I strongly recommend people to always quote things by actual size and only put gauge numbers as a secondary indication and to always qualify gauge numbers if they do quote them (e.g. gauge 12 to ASTM sheet metal standards).