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Metric to Inch Conversion Chart
This Metric to Fractional Inch Conversion Chart provides a quick reference for converting millimetre (mm) measurements into common fractional inch and decimal inch sizes.
This chart is useful for engineers, machinists, fabricators, apprentices and workshop professionals when selecting drill sizes, checking measurements and working between metric and imperial standards.
| Millimetres (mm) | Fraction (inches) | Decimal (inches) |
|---|---|---|
| 0.397 | 1/64" | 0.0156" |
| 0.794 | 1/32" | 0.0313" |
| 1.191 | 3/64" | 0.0469" |
| 1.588 | 1/16" | 0.0625" |
| 1.984 | 5/64" | 0.0781" |
| 2.381 | 3/32" | 0.0938" |
| 2.778 | 7/64" | 0.1094" |
| 3.175 | 1/8" | 0.1250" |
| 3.572 | 9/64" | 0.1406" |
| 3.969 | 5/32" | 0.1562" |
| 4.366 | 11/64" | 0.1719" |
| 4.762 | 3/16" | 0.1875" |
| 5.159 | 13/64" | 0.2031" |
| 5.556 | 7/32" | 0.2188" |
| 5.953 | 15/64" | 0.2344" |
| 6.350 | 1/4" | 0.2500" |
| 6.747 | 17/64" | 0.2656" |
| 7.144 | 9/32" | 0.2812" |
| 7.541 | 19/64" | 0.2969" |
| 7.938 | 5/16" | 0.3125" |
| 8.334 | 21/64" | 0.3281" |
| 8.731 | 11/32" | 0.3438" |
| 9.128 | 23/64" | 0.3594" |
| 9.525 | 3/8" | 0.3750" |
| 9.922 | 25/64" | 0.3906" |
| 10.319 | 13/32" | 0.4062" |
| 10.716 | 27/64" | 0.4219" |
| 11.112 | 7/16" | 0.4375" |
| 11.509 | 29/64" | 0.4531" |
| 11.906 | 15/32" | 0.4688" |
| 12.303 | 31/64" | 0.4844" |
| 12.700 | 1/2" | 0.5000" |
| 13.097 | 33/64" | 0.5156" |
| 13.494 | 17/32" | 0.5312" |
| 13.891 | 35/64" | 05469" |
| 14.288 | 9/16" | 0.5625" |
| 14.684 | 37/64" | 0.5781" |
| 15.081 | 19/32" | 0.5938" |
| 15.479 | 39/64" | 0.6094" |
| 15.875 | 5/8" | 0.6250" |
| 16.272 | 41/64" | 0.6406" |
| 16.669 | 21/32" | 06562" |
| 17.066 | 43/64" | 06719" |
| 17.462 | 11/16" | 06875" |
| 17.859 | 45/64" | 0.7031" |
| 18.256 | 23/32" | 0.7188" |
| 18.653 | 47/64" | 0.7344" |
| 19.050 | 3/4" | 0.7500" |
| 19.447 | 49/64" | 0.7656" |
| 19.844 | 25/32" | 0.7812" |
| 20.241 | 51/64" | 0.7969" |
| 20.638 | 13/16" | 0.8125 |
| 21.034 | 53/64" | 0.8281" |
| 21.431 | 27/32" | 0.8438" |
| 21.828 | 55/64" | 0.8594" |
| 22.225 | 7/8" | 0.8750 |
| 22.622 | 57/64" | 0.8906 |
| 23.019 | 29/32" | 0.9062" |
| 23.416 | 59/64" | 0.9219" |
| 23.812 | 15/16" | 0.9375" |
| 24.209 | 61/64" | 0.9531" |
| 24.606 | 31/32" | 0.9688" |
| 25.003 | 63/64" | 0.9844" |
| 25.400 | 1" | 1.0000" |
| 25.797 | 1.1/64" | 1.0156" |
| 26.194 | 1.1/32" | 1.0312" |
| 26.591 | 1.3/64" | 1.0469" |
| 26.988 | 1.1/16" | 1.0625" |
| 27.384 | 1.5/64" | 1.0781" |
| 27.781 | 1.3/32" | 1.0938" |
| 28.178 | 1.7/64" | 1.1094" |
| 28.575 | 1.1/8" | 1.1250" |
| 28.972 | 1.9/64" | 1.1406" |
| 29.369 | 1.5/32" | 1.1562" |
| 29.766 | 1.11/64" | 1.1719" |
| 30.162 | 1.3/16" | 1.1875" |
| 30.559 | 1.13/64" | 1.2031" |
| 30.956 | 1.7/32" | 1.2188" |
| 31.353 | 1.15/64" | 1.2344" |
| 31.750 | 1.1/4" | 1.2500" |
| 32.147 | 1.17/64" | 1.2656" |
| 32.544 | 1.9/32" | 1.2812" |
| 32.941 | 1.19/64" | 1.2969" |
| 33.338 | 1.5/16" | 1.3125" |
| 33.734 | 1.21/64" | 1.3281" |
| 34.131 | 1.11/32" | 1.3438" |
| 34.528 | 1.23/64" | 1.3594" |
| 34.925 | 1.3/8" | 1.3750" |
| 35.322 | 1.25/64" | 1.3906" |
| 35.719 | 1.13/32" | 1.4062" |
| 36.116 | 1.27/64" | 1.4219" |
| 36.512 | 1.7/16" | 1.4375" |
| 36.909 | 1.29/64" | 1.4531" |
| 37.306 | 1.15/32" | 1.4688" |
| 37.703 | 1.31/64" | 1.4844" |
| 38.100 | 1.1/2" | 1.5000" |
| 38.497 | 1.33/64" | 1.5156" |
| 38.894 | 1.17/32" | 1.5312" |
| 39.291 | 1.35/64" | 1.5469" |
| 39.688 | 1.9/16" | 1.5625" |
| 40.084 | 1.37/64" | 1.5781" |
| 40.481 | 1.19/32" | 1.5938" |
| 40.878 | 1.39/64" | 1.6094" |
| 41.275 | 1.5/8" | 1.6250" |
| 41.672 | 1.41/64" | 1.6406" |
| 42.069 | 1.21/32" | 1.6562" |
| 42.466 | 1.43/64" | 1.6719" |
| 42.862 | 1.11/16" | 1.6875" |
| 43.259 | 1.45/64" | 1.7031" |
| 43.656 | 1.23/32" | 1.7188" |
| 44.053 | 1.47/64" | 1.7344" |
| 44.450 | 1.3/4" | 1.7500" |
| 44.847 | 1.49/64" | 1.7656" |
| 45.244 | 1.25/32" | 1.7812" |
| 45.641 | 1.51/64" | 1.7969" |
| 46.038 | 1.13/16" | 1.8125" |
| 46.434 | 1.53/64" | 1.8281" |
| 46.831 | 1.27/32" | 1.8438" |
| 47.228 | 1.55/64" | 1.8594" |
| 47.625 | 1.7/8" | 1.8750" |
| 48.022 | 1.57/64" | 1.8906" |
| 48.419 | 1.29/32" | 1.9062" |
| 48.816 | 1.59/64" | 1.9219" |
| 49.212 | 1.15/16" | 1.9375" |
| 49.609 | 1.61/64" | 1.9531" |
| 50.006 | 1.31/32" | 1.9688" |
| 50.403 | 1.63/64" | 1.9844" |
| 50.800 | 2" | 2.0000" |
Converting Millimetres to Inches
To convert millimetres to inches, divide the millimetre value by 25.4. For example:
- 10 mm ÷ 25.4 = 0.3937 inches
- 25 mm ÷ 25.4 = 0.9843 inches
- 50 mm ÷ 25.4 = 1.9685 inches
Converting Inches to Millimetres
To convert inches to millimetres, multiply the inch value by 25.4. For example:
- 0.5 inches × 25.4 = 12.7 mm
- 1 inch × 25.4 = 25.4 mm
- 2 inches × 25.4 = 50.8 mm
Common Metric Tap and Drill Equivalents
- M2: 2 mm ≈ #71 drill (0.026")
- M3: 3 mm ≈ #29 drill (0.136")
- M4: 4 mm ≈ #21 drill (0.159")
- M5: 5 mm ≈ #8 drill (0.199")
- M6: 6 mm ≈ #4 drill (0.209")
- M8: 8 mm ≈ #7/32" (0.219")
- M10: 10 mm ≈ #17/64" (0.266")
Key Conversion Formulas
Millimetres to Inches: Divide mm by 25.4
Inches to Millimetres: Multiply inches by 25.4
Standard Conversion Factor: 1 inch = 25.4 mm (exact)