Dowel Size Information
A dowel pin is a precisely ground cylindrical pin, pressed into a reamed hole, used to accurately locate two parts relative to each other — for example, positioning a jig plate, aligning a die set, or locating a housing before it's bolted together. Unlike a bolt or screw, a dowel pin isn't meant to carry the main clamping load; its job is purely to fix the position of the parts precisely and repeatably, so the mating holes are reamed to a tight tolerance rather than drilled to a standard clearance size.
The charts below give standard dimensions for metric and inch dowel pins. Dimensions shown are in inches and mm; if you need to convert between the two, use our universal converter.
Dimension charts for Metric and Inch Dowel Pins.
Dimensions shown are in Inches and mm if you wish to convert them, please use our universal converter.
DOWEL PINS - METRIC
| DOWEL PIN DIMENSIONS - METRIC | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| NOMINAL SIZE | PIN DIAMETER (A) | POINT DIAMETER (B) | CROWN HEIGHT (C) | CROWN RADIUS (R) | CALCULATED SINGLE SHEAR STRENGTH | RECOMMENDED HOLE SIZE | ||||
| MAX | MIN | MAX | MIN | MAX | MIN | kN | POUNDS | MAX | MIN | |
| 3 | 3.008 | 3.003 | 2.9 | 2.6 | 0.8 | 0.3 | 7.4 | 1,670 | 3.000 | 2.987 |
| 4 | 4.009 | 4.004 | 3.9 | 3.6 | 0.9 | 0.4 | 13.2 | 2,965 | 4.000 | 3.987 |
| 5 | 5.009 | 5.004 | 4.9 | 4.6 | 1.0 | 0.4 | 20.6 | 4,635 | 5.000 | 4.987 |
| 6 | 6.010 | 6.004 | 5.8 | 5.4 | 1.1 | 0.4 | 29.7 | 6,650 | 6.000 | 5.987 |
| 8 | 8.012 | 8.006 | 7.8 | 7.4 | 1.3 | 0.5 | 52.5 | 11,850 | 8.000 | 7.987 |
| 10 | 10.012 | 10.006 | 9.8 | 9.4 | 1.4 | 0.6 | 82.5 | 18,550 | 10.000 | 9.987 |
| 12 | 12.013 | 12.007 | 11.8 | 11.4 | 1.6 | 0.6 | 119.0 | 26,700 | 12.000 | 11.985 |
| 16 | 16.013 | 16.007 | 15.8 | 15.3 | 1.8 | 0.8 | 211.0 | 47,450 | 16.000 | 15.985 |
| 20 | 20.014 | 20.008 | 19.8 | 19.3 | 2.0 | 0.8 | 330.0 | 74,000 | 20.000 | 19.983 |
| 25 | 25.014 | 25.008 | 24.8 | 24.3 | 2.3 | 1.0 | 515.0 | 116,000 | 25.000 | 24.983 |
DOWEL PINS - INCHES
| DOWEL PIN DIMENSIONS - INCHES | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| NOMINAL SIZE | PIN DIAMETER (A) | (B) | (D) | (R) | CALCULATED SINGLE SHEAR STRENGTH | RECOMMENDED HOLE SIZE | ||||
| .0002 over nom. | .001 over nom. | |||||||||
| MAX | MIN | MAX | MIN | MAX | MIN | MIN | POUNDS | MAX | MIN | |
| 1/16 | 0.0628 | 0.0626 | 0.0636 | 0.0634 | 0.058 | 0.016 | 0.008 | 465 | 0.0625 | 0.0620 |
| 3/32 | 0.0941 | 0.0939 | 0.0949 | 0.0947 | 0.089 | 0.018 | 0.012 | 1,035 | 0.0937 | 0.0932 |
| 1/8 | 0.1253 | 0.1251 | 0.1261 | 0.1259 | 0.120 | 0.022 | 0.016 | 1,845 | 0.1250 | 0.1245 |
| 5/32 | 0.1565 | 0.1563 | 0.1573 | 0.1571 | 0.150 | 0.022 | 0.020 | 2,880 | 0.1562 | 0.1557 |
| 3/16 | 0.1878 | 0.1876 | 0.1886 | 0.1884 | 0.180 | 0.023 | 0.023 | 4,140 | 0.1875 | 0.1870 |
| 1/4 | 0.2503 | 0.2501 | 0.2511 | 0.2509 | 0.240 | 0.031 | 0.031 | 7,370 | 0.2500 | 0.2495 |
| 5/16 | 0.3128 | 0.3126 | 0.3136 | 0.3134 | 0.302 | 0.034 | 0.039 | 11,500 | 0.3125 | 0.3120 |
| 3/8 | 0.3753 | 0.3751 | 0.3761 | 0.3759 | 0.365 | 0.038 | 0.047 | 16,580 | 0.3750 | 0.3745 |
| 7/16 | 0.4378 | 0.4376 | 0.4386 | 0.4384 | 0.424 | 0.047 | 0.055 | 22,540 | 0.4375 | 0.4370 |
| 1/2 | 0.5003 | 0.5001 | 0.5011 | 0.5009 | 0.486 | 0.047 | 0.063 | 29,460 | 0.5000 | 0.4995 |
| 9/16 | 0.5628 | 0.5626 | 0.5636 | 0.5634 | 0.548 | 0.047 | 0.070 | 37,270 | 0.5625 | 0.5620 |
| 5/8 | 0.6253 | 0.6251 | 0.6261 | 0.6259 | 0.611 | 0.047 | 0.078 | 46,020 | 0.6250 | 0.6245 |
| 3/4 | 0.7503 | 0.7501 | 0.7511 | 0.7509 | 0.735 | 0.059 | 0.094 | 66,270 | 0.7500 | 0.7495 |
| 7/8 | 0.8753 | 0.8751 | 0.8761 | 0.8759 | 0.860 | 0.059 | 0.109 | 90,190 | 0.8750 | 0.8745 |
| 1 | 1.0003 | 1.0001 | 1.0011 | 1.0009 | 0.980 | 0.059 | 0.125 | 117,810 | 1.0000 | 0.9995 |
RELATED PAGES
FREQUENTLY ASKED QUESTIONS
What’s the difference between a dowel pin and a standard pin or rod?
A dowel pin is manufactured to a much tighter diameter tolerance than plain rod stock, usually ground rather
than turned, specifically so it can be pressed into a reamed hole with a controlled, repeatable interference
fit.
What size hole should I ream for a dowel pin?
This depends on the fit class required, but as a general rule the reamed hole is sized just under the dowel’s
nominal diameter to give a light press fit. Always check the specific dowel standard and fit class you’re
working to rather than assuming a single rule applies universally.
Can a dowel pin carry a shear load?
Yes — dowel pins are often used to take shear loads between two parts, in addition to their locating
function, since their precise fit means multiple dowels share load evenly. However, they aren’t intended to
replace the primary clamping fasteners (bolts or screws) holding the assembly together.
How do I remove a dowel pin?
Since dowel pins are a tight press fit, they’re usually removed by pressing or driving them out from the
opposite side, or with a dowel pin puller for blind holes. Avoid levering or bending the pin, which can damage
the reamed hole.
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