Metric Conversion to Fractional and Decimal Inches

Use this quick reference metric conversion table to quickly convert your metric drill bits to fractional, or decimal-inch equivalents when you need to drill holes for your woodturning projects. Additional sizes and types of bits will be added to this metric conversion table in the near future. Print a copy of this table out and keep it in your studio near your drill bits as a handy cross-reference when needed.



Millimetres Fractional Eq. Decimal-Inch
.397 1/64 .015625
.794 1/32 .03125
1.191 3/64 .046875
1.588 1/16 .0625
1.984 5/64 .078125
2.381 3/32 .09375
2.778 7/64 .109375
3.175 1/8 .125
3.572 9/64 .140625
3.969 5/32 .15625
4.366 11/64 .171875
4.762 3/16 .1875
5.159 13/64 .203125
5.556 7/32 .21875
5.953 15/64 .234375
6.350 1/4 .25
6.747 17/64 .265625
7.144 9/32 .28125
7.541 19/64 296875
7.938 5/16 .3125
8.334 21/64 .328125
8.731 11/32 .34375
9.128 23/64 .359375
9.525 3/8 .375
9.922 25/64 .390625
10.319 13/32 .40625
10.716 27/64 .421875
11.112 7/16 .4375
11.509 29/64 .453125
11.906 15/32 .46875
12.303 31/64 .484375
12.700 1/2 .50
13.097 33/64 .515625
13.494 17/32 .53125
13.891 35/64 ..546875
14.288 9/16 .5625
14.684 37/64 .578125
15.081 19/32 .59375
15.478 39/64 .609375
15.875 5/8 .625
16.272 41/64 .640625
16.669 21/32 .65625
17.066 43/64 .671875
17.462 11/16 .6875
17.859 45/64 .703125
18.256 23/32 .71875
18.653 47/64 .734375
19.050 3/4 .75
19.447 49/64 .765625
19.844 25/32 .78125
20.241 51/64 .796875
20.638 13/16 .8125
21.034 53/64 .828125
21.431 27/32 .84375
21.828 55/64 .859375
22.225 7/8 .875
22.622 57/64 .890625
23.019 29/32 .90625
23.416 59/64 .921875
23.812 15/16 .9375
24.209 61/64 .953125
24.606 31/32 .96875
25.003 63/64 .984375
25.400 1 1.000

Safety Note: Always follow all manufacturers safety instructions before working with your lathe, or any of the tools or products you may use. If you are unsure about any operation, obtain competent professional instruction before proceeding. Use and wear all necessary safety devices during turning and observe safe woodturning practices to prevent accident or injury.


Steven D. Russell is a professional studio woodturner, teacher and writer. He has written numerous articles for international woodturning magazines, which have been published in more than 78 countries around the world. Steve has demonstrated in numerous cities across the United States. His studio, Eurowood Werks, specializes in bowls, platters and hollow forms with unique visual and tactile treatments.

Steve is also the current and founding President of the Lone Star Woodturners Association, Inc., an AAW member chapter. The LSWA is a 501(c)3 non-profit educational organization dedicated to teaching and demonstrating the art and craft of woodturning.

Steve is also a featured writer for the Guild of Master Craftsman's "Woodturning" magazine, published in London England. Woodturning magazine is the world's leading magazine for woodturners. Look for his articles covering technical topics, or project based articles in an upcoming issue.