Tools & Materials reference
Fraction to Decimal Chart
Inch fractions with the count of 64ths, decimal inches, thousandths and millimetres. For reading a tape measure, a micrometer or a dial indicator.
- Basis Computed from definitions
- Last checked 2026-08-17
- Sheet portrait
Both unit systems load with the page. The filter searches every column.
| Fraction | 64ths | Decimal | Thou | Millimetres |
|---|---|---|---|---|
| in | in / 1000 | mm | ||
| 1/64 | 1 | 0.0156 | 15.6 | 0.397 |
| 1/32 | 2 | 0.0313 | 31.3 | 0.794 |
| 3/64 | 3 | 0.0469 | 46.9 | 1.191 |
| 1/16 | 4 | 0.0625 | 62.5 | 1.588 |
| 5/64 | 5 | 0.0781 | 78.1 | 1.984 |
| 3/32 | 6 | 0.0938 | 93.8 | 2.381 |
| 7/64 | 7 | 0.1094 | 109.4 | 2.778 |
| 1/8 | 8 | 0.1250 | 125.0 | 3.175 |
| 9/64 | 9 | 0.1406 | 140.6 | 3.572 |
| 5/32 | 10 | 0.1563 | 156.3 | 3.969 |
| 11/64 | 11 | 0.1719 | 171.9 | 4.366 |
| 3/16 | 12 | 0.1875 | 187.5 | 4.762 |
| 13/64 | 13 | 0.2031 | 203.1 | 5.159 |
| 7/32 | 14 | 0.2188 | 218.8 | 5.556 |
| 15/64 | 15 | 0.2344 | 234.4 | 5.953 |
| 1/4 | 16 | 0.2500 | 250.0 | 6.350 |
| 17/64 | 17 | 0.2656 | 265.6 | 6.747 |
| 9/32 | 18 | 0.2813 | 281.3 | 7.144 |
| 19/64 | 19 | 0.2969 | 296.9 | 7.541 |
| 5/16 | 20 | 0.3125 | 312.5 | 7.938 |
| 21/64 | 21 | 0.3281 | 328.1 | 8.334 |
| 11/32 | 22 | 0.3438 | 343.8 | 8.731 |
| 23/64 | 23 | 0.3594 | 359.4 | 9.128 |
| 3/8 | 24 | 0.3750 | 375.0 | 9.525 |
| 25/64 | 25 | 0.3906 | 390.6 | 9.922 |
| 13/32 | 26 | 0.4063 | 406.3 | 10.319 |
| 27/64 | 27 | 0.4219 | 421.9 | 10.716 |
| 7/16 | 28 | 0.4375 | 437.5 | 11.112 |
| 29/64 | 29 | 0.4531 | 453.1 | 11.509 |
| 15/32 | 30 | 0.4688 | 468.8 | 11.906 |
| 31/64 | 31 | 0.4844 | 484.4 | 12.303 |
| 1/2 | 32 | 0.5000 | 500.0 | 12.700 |
| 33/64 | 33 | 0.5156 | 515.6 | 13.097 |
| 17/32 | 34 | 0.5313 | 531.3 | 13.494 |
| 35/64 | 35 | 0.5469 | 546.9 | 13.891 |
| 9/16 | 36 | 0.5625 | 562.5 | 14.288 |
| 37/64 | 37 | 0.5781 | 578.1 | 14.684 |
| 19/32 | 38 | 0.5938 | 593.8 | 15.081 |
| 39/64 | 39 | 0.6094 | 609.4 | 15.478 |
| 5/8 | 40 | 0.6250 | 625.0 | 15.875 |
| 41/64 | 41 | 0.6406 | 640.6 | 16.272 |
| 21/32 | 42 | 0.6563 | 656.3 | 16.669 |
| 43/64 | 43 | 0.6719 | 671.9 | 17.066 |
| 11/16 | 44 | 0.6875 | 687.5 | 17.463 |
| 45/64 | 45 | 0.7031 | 703.1 | 17.859 |
| 23/32 | 46 | 0.7188 | 718.8 | 18.256 |
| 47/64 | 47 | 0.7344 | 734.4 | 18.653 |
| 3/4 | 48 | 0.7500 | 750.0 | 19.050 |
| 49/64 | 49 | 0.7656 | 765.6 | 19.447 |
| 25/32 | 50 | 0.7813 | 781.3 | 19.844 |
| 51/64 | 51 | 0.7969 | 796.9 | 20.241 |
| 13/16 | 52 | 0.8125 | 812.5 | 20.638 |
| 53/64 | 53 | 0.8281 | 828.1 | 21.034 |
| 27/32 | 54 | 0.8438 | 843.8 | 21.431 |
| 55/64 | 55 | 0.8594 | 859.4 | 21.828 |
| 7/8 | 56 | 0.8750 | 875.0 | 22.225 |
| 57/64 | 57 | 0.8906 | 890.6 | 22.622 |
| 29/32 | 58 | 0.9063 | 906.3 | 23.019 |
| 59/64 | 59 | 0.9219 | 921.9 | 23.416 |
| 15/16 | 60 | 0.9375 | 937.5 | 23.813 |
| 61/64 | 61 | 0.9531 | 953.1 | 24.209 |
| 31/32 | 62 | 0.9688 | 968.8 | 24.606 |
| 63/64 | 63 | 0.9844 | 984.4 | 25.003 |
| 1 | 64 | 1.0000 | 1,000.0 | 25.400 |
No size matches that. Clear the filter to see the full table.
Sources mapped to columns
One line per source, listing exactly which columns it covers. A column cannot appear in the table without appearing here, because the build fails on it.
| Columns | Source | Basis |
|---|---|---|
| Fraction 64ths Decimal in Thou in / 1000 Millimetres mm | The inch One inch is 25.4 millimetres exactly, by international definition since 1959. Thousandths are the decimal inch × 1000. Nothing on this page is a measurement. | Definition |
Conditions
- Exact conversions, rounded for display only. No tolerance or fit allowance is implied.
Recomputed from the definitions above on every build · last build audit 2026-08-17
Where the equipment manufacturer specifies a figure for the specific assembly, that figure governs. This is a reference sheet, not a substitute for the instructions that came with the part.
One data set. Two purpose-built sheets.
The printable sheet and the vertical image use different layouts, so neither one sacrifices readability to the other.
Download PDF 
Download PNG Thousandths omitted for legibility. Full table on the site.
How to use this chart
- Filter by any value (fraction, 64ths, decimal, thousandths or millimetres) to find the row it belongs to.
- The 64ths column is for reading a tape measure: count the sixteenths or thirty-seconds and look up the row.
- Thousandths are the column for a dial indicator or a micrometer marked in thou.
- This is a conversion sheet, not a tool list. If you want the nearest drill bit to a measurement, the drill bit size chart is the page for that.
Frequently asked questions
Is 25.4 mm an exact conversion?
Yes. The international yard and pound agreement of 1959 defined the inch as exactly 25.4 mm, so nothing on this page is a measurement or an approximation. Only the display is rounded.
What is a thou?
One thousandth of an inch, 0.001 in, also written as a mil. It is the working unit on most inch-marked micrometers and dial indicators.