UNC coarse thread chart

27 sizes · ThreadRef · free sample of 8 representative sizes

UNC coarse thread chart. The Unified coarse series, #0 to 2-1/2 inch: threads per inch, major, pitch and minor diameters, the tap drill in both inches and millimetres, and the hex across-flats.
Size	TPI	Major dia in	Pitch dia in	Minor dia in	Tap drill in	Tap drill mm	Hex A/F
#6-32 UNC	32	0.138	0.1177	0.1042	0.1065	2.71	not defined
#10-24 UNC	24	0.19	0.1629	0.1449	0.1495	3.8	not defined
1/4-20 UNC	20	0.25	0.2175	0.1959	0.201	5.11	7/16"
5/16-18 UNC	18	0.3125	0.2764	0.2524	0.257	6.53	1/2"
3/8-16 UNC	16	0.375	0.3344	0.3073	0.3125	7.94	9/16"
1/2-13 UNC	13	0.5	0.45	0.4167	0.4219	10.72	3/4"
5/8-11 UNC	11	0.625	0.566	0.5266	0.5313	13.49	15/16"
3/4-10 UNC	10	0.75	0.6851	0.6418	0.6563	16.67	1-1/8"

Dimensions per ASME B1.1 (Unified inch screw threads); wrench sizes per ASME B18.2.1.

Torque figures are estimates that depend on the stated nut-factor assumption. Verify against your fastener manufacturer's data and joint requirements before assembly.

Every figure on this chart is also free on its own size page - tap any size in the first column to open it, or browse the full reference. Premium pays for the sheet, not the numbers.