Inch Thread Gage Pitch Diameters

(Sizes 1" Through 1 5/16")

Thread Size
Plug Gage
Ring Gage
GO

2B & 3B

NO GO

Class 2B

NO GO

Class 3B

GO

Class 2A

NO GO

Class 2A

GO

Class 3A

NO GO

Class 3A

1-8 UNC
.9188"
.9276"
.9254"
.9168"
.9100"
.9188"
.9137"
1-12 UNF
.9459"
.9535"
.9516"
.9441"
.9382"
.9459"
.9415"
1-14 UNS
.9536"
.9609"
.9590"
.9519"
.9463"
.9536"
.9494"
1-16 UN
.9594"
.9659"
.9643"
.9579"
.9529"
.9594"
.9557"
1-20 UNEF
.9675"
.9734"
.9719"
.9661"
.9616"
.9675"
.9641"
1-28 UN
.9768"
.9820"
.9807"
.9756"
.9716"
.9768"
.9738"
1-32 UN
.9797"
.9846"
.9834"
.9786"
.9748"
.9797"
.9769"
1 1/16-8 UN
.9813"
.9902"
.9880"
.9793"
.9725"
.9813"
.9762"
1 1/16-12 UN
1.0084"
1.0158"
1.0139"
1.0067"
1.0010"
1.0084"
1.0042"
1 1/16-16 UN
1.0219"
1.0284"
1.0268"
1.0204"
1.0154"
1.0219"
1.0182"
1 1/16-18 UNEF
1.0264"
1.0326"
1.0310"
1.0250"
1.0203"
1.0264"
1.0228"
1 1/16-20 UN
1.0300"
1.0359"
1.0344"
1.0286"
1.0241"
1.0300"
1.0266"
1 1/16-28 UN
1.0393"
1.0445"
1.0432"
1.0381"
1.0341"
1.0393"
1.0363"
1 1/8-7 UNC
1.0322"
1.0416"
1.0393"
1.0300"
1.0228"
1.0322"
1.0268"
1 1/8-8 UN
1.0438"
1.0528"
1.0505"
1.0417"
1.0348"
1.0438"
1.0386"
1 1/8-12 UNF
1.0709"
1.0787"
1.0768"
1.0691"
1.0631"
1.0709"
1.0664"
1 1/8-16 UN
1.0844"
1.0909"
1.0893"
1.0829"
1.0779"
1.0844"
1.0807"
1 1/8-18 UNEF
1.0889"
1.0951"
1.0935"
1.0875"
1.0828"
1.0889"
1.0853"
1 1/8-20 UN
1.0925"
1.0984"
1.0969"
1.0911"
1.0866"
1.0925"
1.0891"
1 1/8-28 UN
1.1018"
1.1070"
1.1057"
1.1006"
1.0966"
1.1018"
1.0988"
1 3/16-8 UN
1.1063"
1.1154"
1.1131"
1.1042"
1.0972"
1.1063"
1.1011"
1 3/16-12 UN
1.1334"
1.1409"
1.1390"
1.1317"
1.1259"
1.1334"
1.1291"
1 3/16-16 UN
1.1469"
1.1519"
1.1535"
1.1454"
1.1403"
1.1469"
1.1431"
1 3/16-18 UNEF
1.1514"
1.1577"
1.1561"
1.1499"
1.1450"
1.1514"
1.1478"
1 3/16-20 UN
1.1550"
1.1611"
1.1595"
1.1536"
1.1489"
1.1550"
1.1515"
1 3/16-28 UN
1.1643"
1.1696"
1.1683"
1.1631"
1.1590"
1.1643"
1.1612"
1 1/4-7 UNC
1.1572"
1.1668"
1.1644"
1.1550"
1.1476"
1.1572"
1.1517"
1 1/4-8 UN
1.1688"
1.1780"
1.1757"
1.1667"
1.1597"
1.1688"
1.1635"
1 1/4-12 UNF
1.1959"
1.2039"
1.2019"
1.1941"
1.1879"
1.1959"
1.1913"
1 1/4-16-UN
1.2094"
1.2160"
1.2144"
1.2079"
1.2028"
1.2094"
1.2056"
1 1/4-18 UNEF
1.2139"
1.2202"
1.2186"
1.2124"
1.2075"
1.2139"
1.2103"
1 1/4-20 UN
1.2175"
1.2236"
1.2220"
1.2161"
1.2114"
1.2175"
1.2140"
1 1/4-28 UN
1.2268"
1.2321"
1.2308"
1.2256"
1.2215"
1.2268"
1.2237"
1 5/16-8 UN
1.2313"
1.2405"
1.2382"
1.2292"
1.2221"
1.2313"
1.2260"
1 5/16-12 UN
1.2584"
1.2659"
1.2640"
1.2567"
1.2509"
1.2584"
1.2541"
1 5/16-16 UN
1.2719"
1.2785"
1.2769"
1.2704"
1.2653"
1.2719"
1.2681"
1 5/16-18 UNEF
1.2764"
1.2827"
1.2811"
1.2749"
1.2700"
1.2764"
1.2728"
1 5/16-20 UN
1.2800"
1.2861"
1.2845"
1.2786"
1.2739"
1.2800"
1.2765"
1 5/16-28 UN
1.2893"
1.2946"
1.2933"
1.2881"
1.2840"
1.2893"
1.2862"
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