Head size, prong extension, cross-hole and drill sizes for cotter pins and clevis pins (ASME B18.8.1), hardened ground dowel pins and slotted spring (roll) pins (ASME B18.8.2), in inches.
Pins are sized by their nominal diameter. A cotter pin is a folded wire with an eye: it goes through a drilled bolt, clevis pin or castle nut and its prongs are bent back to lock it. A clevis pin is a headed pin for a clevis, yoke or linkage, held in by a cotter pin through the cross hole near its end. A dowel pin (hardened ground) locates two parts exactly, pressed into a reamed hole. A slotted spring pin (roll pin) is a split tube made bigger than its hole: driven into a drilled hole, it squeezes and holds by spring force.
The letters match the table columns.
| Size | Head dia C min | Prong extension D min |
|---|---|---|
| 1/32″ | .06 | .01 |
| 3/64″ | .09 | .02 |
| 1/16″ | .12 | .03 |
| 5/64″ | .16 | .04 |
| 3/32″ | .19 | .04 |
| 7/64″ | .22 | .05 |
| 1/8″ | .25 | .06 |
| 9/64″ | .28 | .06 |
| 5/32″ | .31 | .07 |
| 3/16″ | .38 | .09 |
| 7/32″ | .44 | .10 |
| 1/4″ | .50 | .11 |
| 5/16″ | .62 | .14 |
| 3/8″ | .75 | .16 |
| 7/16″ | .88 | .20 |
| 1/2″ | 1.00 | .23 |
| 5/8″ | — | — |
| 3/4″ | 1.50 | .36 |
Wire width and the hole size aren’t on our chart — our two sources don’t agree on them; give us a call. A dash: our sources differ.
| Size | Shank dia A max | Head dia B max | Head height C max | Chamfer D | Cross hole E max | Point dia F max | Length G / head to hole H max | Cotter pin |
|---|---|---|---|---|---|---|---|---|
| 3/16″ | .186 | .32 | .07 | .02 | .088 | .15 | .58 / .504 | 1/16″ |
| 1/4″ | .248 | .38 | .10 | .03 | .088 | .21 | .77 / .692 | 1/16″ |
| 5/16″ | .311 | .44 | .10 | .03 | .119 | .26 | .94 / .832 | 3/32″ |
| 3/8″ | .373 | .51 | .13 | .03 | .119 | .33 | 1.06 / .958 | 3/32″ |
| 7/16″ | .436 | .57 | .16 | .04 | .119 | .39 | 1.19 / 1.082 | 3/32″ |
| 1/2″ | .496 | .63 | .16 | .04 | .151 | .44 | 1.36 / 1.223 | 1/8″ |
| 5/8″ | .621 | .82 | .21 | .06 | .151 | .56 | 1.61 / 1.473 | 1/8″ |
| 3/4″ | .746 | .94 | .26 | .07 | .182 | .68 | 1.91 / 1.739 | 5/32″ |
| 7/8″ | .871 | 1.04 | .32 | .09 | .182 | .80 | 2.16 / 1.989 | 5/32″ |
| 1″ | .996 | 1.19 | .35 | .10 | .182 | .93 | 2.41 / 2.239 | 5/32″ |
Maximum sizes. G and H are for the standard’s listed length; a clevis pin of another length has its hole placed for that length.
| Size | Dia A max / min (standard series) | Point dia B max / min | Crown height C max |
|---|---|---|---|
| 1/16″ | — / — | — / — | — |
| 5/64″ | — / — | — / — | — |
| 3/32″ | — / — | — / — | — |
| 1/8″ | .1253 / .1251 | .120 / .110 | .041 |
| 5/32″ | — / — | — / — | — |
| 3/16″ | .1878 / .1876 | .180 / .170 | .062 |
| 1/4″ | .2503 / .2501 | .240 / .230 | .083 |
| 5/16″ | .3128 / .3126 | .302 / .290 | .104 |
| 3/8″ | .3753 / .3751 | .365 / .350 | .125 |
| 7/16″ | — / — | .424 / .409 | .146 |
| 1/2″ | .5003 / .5001 | .486 / .471 | .167 |
| 5/8″ | .6253 / .6251 | .611 / .595 | .208 |
| 3/4″ | .7503 / .7501 | .735 / .715 | .250 |
| 7/8″ | .8753 / .8751 | .860 / .840 | .293 |
| 1″ | 1.0003 / 1.0001 | .980 / .960 | .333 |
Standard series. The oversize series, hole sizes and shear loads aren’t listed — we have only one independent source for them. A dash: our sources differ, or only one lists it.
| Size | Drill hole max / min | Pin dia A max / min | Chamfer dia B max | Chamfer length C max / min | Wall F | Double shear min, lb (carbon / 420 SS) | Double shear min, lb (18-8 SS) |
|---|---|---|---|---|---|---|---|
| 1/16″ | .065 / .062 | .069 / .066 | .059 | .028 / .007 | .012 | 430 | 250 |
| 5/64″ | .081 / .078 | .086 / .083 | .075 | .032 / .008 | .018 | 800 | 460 |
| 3/32″ | .097 / .094 | .103 / .099 | .091 | .038 / .008 | .022 | 1,150 | 670 |
| 1/8″ | .129 / .125 | .135 / .131 | .122 | .044 / .008 | .028 | 1,875 | 1,090 |
| 9/64″ | — / — | — / — | — | — / — | — | — | — |
| 5/32″ | .160 / .156 | .167 / .162 | .151 | .048 / .010 | .032 | 2,750 | 1,600 |
| 3/16″ | .192 / .187 | .199 / .194 | .182 | .055 / .011 | .040 | 4,150 | 2,425 |
| 7/32″ | — / — | — / — | — | — / — | — | — | — |
| 1/4″ | .256 / .250 | .264 / .258 | .245 | .065 / .012 | .048 | 7,050 | 4,100 |
| 5/16″ | .318 / .312 | .330 / .321 | .306 | .080 / .014 | .062 | 10,800 | 6,300 |
| 3/8″ | .382 / .375 | .395 / .385 | .368 | .095 / .016 | .077 | 16,300 | 9,500 |
| 7/16″ | — / — | — / — | — | — / — | — | — | — |
| 1/2″ | .510 / .500 | .524 / .513 | .485 | .110 / .025 | .094 | 27,100 | 15,800 |
| 5/8″ | — / — | — / — | — | — / — | — | — | — |
| 3/4″ | — / — | — / — | — | — / — | — | — | — |
The pin is made bigger than its hole and squeezes in. A dash: our two sources don’t both list this size — give us a call.
Good to know
Match a clevis pin to its cotter pin with the last column of the clevis table. Shear loads are minimums for the pin in double shear (cut in two places).
Quick answers
- What size cotter pin goes in a 1/2 inch clevis pin?
- A 1/8″ cotter pin (ASME B18.8.1).
- What cotter pin fits each clevis pin size?
- 3/16″ clevis – 1/16″ cotter, 1/4″ clevis – 1/16″ cotter, 5/16″ clevis – 3/32″ cotter, 3/8″ clevis – 3/32″ cotter, 7/16″ clevis – 3/32″ cotter, 1/2″ clevis – 1/8″ cotter, 5/8″ clevis – 1/8″ cotter, 3/4″ clevis – 5/32″ cotter, 7/8″ clevis – 5/32″ cotter, 1″ clevis – 5/32″ cotter.
- What size hole do I drill for a 1/4 inch roll pin?
- .256″ max, .250″ min (slotted spring pin, ASME B18.8.2).
- How big is the head on a 1/8 inch cotter pin?
- At least .25″ across (head dia C min).
- How big is the head on a 3/8 inch clevis pin?
- .51″ across, maximum.