Workshop Fraction to Decimal to Millimeter Conversion Chart (1/64" to 1")
1 inch = 25.4 millimeters exactly. Common shop conversions: 1/8" = 0.125" = 3.175mm, 1/4" = 0.250" = 6.35mm, 3/8" = 0.375" = 9.525mm, 1/2" = 0.500" = 12.70mm, 5/8" = 0.625" = 15.875mm, and 3/4" = 0.750" = 19.05mm. To convert any caliper decimal to 64ths: N_64 = round(Decimal × 64).
Master Reference Lookup Table
Filter by name or click column headers to sort specifications.
| Action | |||||
|---|---|---|---|---|---|
| 1/64" | 1/64" | 0.0156" | 0.3969mm | 0.4mm close fit | Open Workshop Tool → |
| 1/32" | 2/64" | 0.0313" | 0.7938mm | 0.8mm close fit | Open Workshop Tool → |
| 3/64" | 3/64" | 0.0469" | 1.1906mm | 1.2mm close fit | Open Workshop Tool → |
| 1/16" | 4/64" | 0.0625" | 1.5875mm | 1/16" standard drill | Open Workshop Tool → |
| 5/64" | 5/64" | 0.0781" | 1.9844mm | 2mm close fit | Open Workshop Tool → |
| 3/32" | 6/64" | 0.0938" | 2.3812mm | 2.4mm close fit | Open Workshop Tool → |
| 7/64" | 7/64" | 0.1094" | 2.7781mm | 2.8mm close fit | Open Workshop Tool → |
| 1/8" | 8/64" | 0.1250" | 3.1750mm | 1/8" (3.175mm) / 3.2mm drill | Open Workshop Tool → |
| 9/64" | 9/64" | 0.1406" | 3.5719mm | 3.6mm close fit | Open Workshop Tool → |
| 5/32" | 10/64" | 0.1563" | 3.9688mm | 4mm close fit | Open Workshop Tool → |
| 11/64" | 11/64" | 0.1719" | 4.3656mm | 4.4mm close fit | Open Workshop Tool → |
| 3/16" | 12/64" | 0.1875" | 4.7625mm | 3/16" standard drill | Open Workshop Tool → |
| 13/64" | 13/64" | 0.2031" | 5.1594mm | 5.2mm close fit | Open Workshop Tool → |
| 7/32" | 14/64" | 0.2188" | 5.5562mm | 5.6mm close fit | Open Workshop Tool → |
| 15/64" | 15/64" | 0.2344" | 5.9531mm | 6mm close fit | Open Workshop Tool → |
| 1/4" | 16/64" | 0.2500" | 6.3500mm | 1/4" (6.35mm) / M6 clearance | Open Workshop Tool → |
| 17/64" | 17/64" | 0.2656" | 6.7469mm | 6.7mm close fit | Open Workshop Tool → |
| 9/32" | 18/64" | 0.2813" | 7.1438mm | 7.1mm close fit | Open Workshop Tool → |
| 19/64" | 19/64" | 0.2969" | 7.5406mm | 7.5mm close fit | Open Workshop Tool → |
| 5/16" | 20/64" | 0.3125" | 7.9375mm | 5/16" standard drill | Open Workshop Tool → |
| 21/64" | 21/64" | 0.3281" | 8.3344mm | 8.3mm close fit | Open Workshop Tool → |
| 11/32" | 22/64" | 0.3438" | 8.7313mm | 8.7mm close fit | Open Workshop Tool → |
| 23/64" | 23/64" | 0.3594" | 9.1281mm | 9.1mm close fit | Open Workshop Tool → |
| 3/8" | 24/64" | 0.3750" | 9.5250mm | 3/8" (9.525mm) | Open Workshop Tool → |
| 25/64" | 25/64" | 0.3906" | 9.9219mm | 9.9mm close fit | Open Workshop Tool → |
| 13/32" | 26/64" | 0.4063" | 10.3188mm | 10.3mm close fit | Open Workshop Tool → |
| 27/64" | 27/64" | 0.4219" | 10.7156mm | 10.7mm close fit | Open Workshop Tool → |
| 7/16" | 28/64" | 0.4375" | 11.1125mm | 7/16" standard drill | Open Workshop Tool → |
| 29/64" | 29/64" | 0.4531" | 11.5094mm | 11.5mm close fit | Open Workshop Tool → |
| 15/32" | 30/64" | 0.4688" | 11.9063mm | 11.9mm close fit | Open Workshop Tool → |
| 31/64" | 31/64" | 0.4844" | 12.3031mm | 12.3mm close fit | Open Workshop Tool → |
| 1/2" | 32/64" | 0.5000" | 12.7000mm | 1/2" (12.7mm) / Blum undermount recess | Open Workshop Tool → |
| 33/64" | 33/64" | 0.5156" | 13.0969mm | 13.1mm close fit | Open Workshop Tool → |
| 17/32" | 34/64" | 0.5313" | 13.4938mm | 13.5mm close fit | Open Workshop Tool → |
| 35/64" | 35/64" | 0.5469" | 13.8906mm | 13.9mm close fit | Open Workshop Tool → |
| 9/16" | 36/64" | 0.5625" | 14.2875mm | 9/16" standard drill | Open Workshop Tool → |
| 37/64" | 37/64" | 0.5781" | 14.6844mm | 14.7mm close fit | Open Workshop Tool → |
| 19/32" | 38/64" | 0.5938" | 15.0813mm | 15.1mm close fit | Open Workshop Tool → |
| 39/64" | 39/64" | 0.6094" | 15.4781mm | 15.5mm close fit | Open Workshop Tool → |
| 5/8" | 40/64" | 0.6250" | 15.8750mm | 5/8" (15.875mm) / 16mm drawer side stock | Open Workshop Tool → |
| 41/64" | 41/64" | 0.6406" | 16.2719mm | 16.3mm close fit | Open Workshop Tool → |
| 21/32" | 42/64" | 0.6563" | 16.6688mm | 16.7mm close fit | Open Workshop Tool → |
| 43/64" | 43/64" | 0.6719" | 17.0656mm | 17.1mm close fit | Open Workshop Tool → |
| 11/16" | 44/64" | 0.6875" | 17.4625mm | 11/16" standard drill | Open Workshop Tool → |
| 45/64" | 45/64" | 0.7031" | 17.8594mm | 17.9mm close fit | Open Workshop Tool → |
| 23/32" | 46/64" | 0.7188" | 18.2562mm | 23/32" (18.25mm) / US 3/4" ply actual | Open Workshop Tool → |
| 47/64" | 47/64" | 0.7344" | 18.6531mm | 18.7mm close fit | Open Workshop Tool → |
| 3/4" | 48/64" | 0.7500" | 19.0500mm | 3/4" (19.05mm) / 1x nominal stock thickness | Open Workshop Tool → |
| 49/64" | 49/64" | 0.7656" | 19.4469mm | 19.4mm close fit | Open Workshop Tool → |
| 25/32" | 50/64" | 0.7813" | 19.8438mm | 19.8mm close fit | Open Workshop Tool → |
| 51/64" | 51/64" | 0.7969" | 20.2406mm | 20.2mm close fit | Open Workshop Tool → |
| 13/16" | 52/64" | 0.8125" | 20.6375mm | 13/16" standard drill | Open Workshop Tool → |
| 53/64" | 53/64" | 0.8281" | 21.0344mm | 21mm close fit | Open Workshop Tool → |
| 27/32" | 54/64" | 0.8438" | 21.4313mm | 21.4mm close fit | Open Workshop Tool → |
| 55/64" | 55/64" | 0.8594" | 21.8281mm | 21.8mm close fit | Open Workshop Tool → |
| 7/8" | 56/64" | 0.8750" | 22.2250mm | 7/8" standard drill | Open Workshop Tool → |
| 57/64" | 57/64" | 0.8906" | 22.6219mm | 22.6mm close fit | Open Workshop Tool → |
| 29/32" | 58/64" | 0.9063" | 23.0187mm | 23mm close fit | Open Workshop Tool → |
| 59/64" | 59/64" | 0.9219" | 23.4156mm | 23.4mm close fit | Open Workshop Tool → |
| 15/16" | 60/64" | 0.9375" | 23.8125mm | 15/16" standard drill | Open Workshop Tool → |
| 61/64" | 61/64" | 0.9531" | 24.2094mm | 24.2mm close fit | Open Workshop Tool → |
| 31/32" | 62/64" | 0.9688" | 24.6063mm | 24.6mm close fit | Open Workshop Tool → |
| 63/64" | 63/64" | 0.9844" | 25.0031mm | 25mm close fit | Open Workshop Tool → |
| 1" | 64/64" | 1.0000" | 25.4000mm | 1.00" (25.40mm) exact | Open Workshop Tool → |
Core Mathematical & Engineering Breakdown
Datasheet equations, derivations, and step-by-step worked shop math.
The Exact International Constant: 1 Inch = 25.4 Millimeters
Unlike empirical physical measurements, the conversion factor between the Imperial inch and the International System of Units (SI) millimeter is exact: 1 in = 25.4 mm. Ratified by the international yard and pound agreement of 1959, this constant ensures that 1/8" is exactly 3.175mm, 1/4" is exactly 6.350mm, and 1/2" is exactly 12.700mm. There is zero rounding error in this conversion constant.
How to Convert Caliper Decimals to Nearest 64th or 32nd Fractions
When digital calipers read 0.4375", finding the equivalent shop fraction is straightforward: Multiply the decimal by the target denominator (e.g., 64). 0.4375 × 64 = 28. Because 28/64 simplifies by dividing numerator and denominator by 4, you get 7/16". For uncooperative decimals like 0.450", 0.450 × 64 = 28.8, indicating the measurement is closest to 29/64" (0.4531") with an error of just 0.0031" (0.08mm).
Bridging the Gap: Imperial Woodworking & Metric 3D/Laser Fabrication
Modern makers routinely cross disciplines: American cabinetry utilizes imperial feet, inches, and 16ths; 3D slicers and 3D CAD operate strictly in metric millimeters; and European hinge/slide hardware operates on the System 32 metric standard (32mm hole centers, 5mm line bore pins). Keeping a verified fraction-to-millimeter reference wall chart posted above your table saw and CNC bench prevents catastrophic dimensional mismatch.
Interactive Micro-Tool: Real-Time Calculation
Adjust sliders and inputs below to calculate custom dimensions instantly.
INTERACTIVE CONVERSION ENGINE
Bidirectional real-time conversion between inches, millimeters, and 64ths
Failure Modes & Workshop Troubleshooting Matrix
Common fabrication failures, caliper inspection methods, and prevention rules.
| Failure Mode | Root Cause | Caliper / Scale Check | Shop Prevention |
|---|---|---|---|
| Drilled bolt hole is too tight for metric hardware | Using a 1/4" drill bit (6.35mm) for an M6 bolt with tight clearance or M6 dowel | M6 bolt nominal is 6.00mm, but M6 shoulder screw may require 6.50mm (17/64") | Consult drill equivalency column before selecting imperial bits for metric hardware |
| 3D printed insert does not press-fit into wood mortise | CAD model designed in mm using rough rounded conversion (e.g., assuming 1/2" is 12mm or 13mm) | Actual 1/2" router bit cuts a 12.70mm slot, creating a 0.70mm loose fit with 12.0mm printed part | Design CAD models to exact 12.70mm dimension; account for printer expansion tolerance |
| Drawer box binding on European slide runners | Converting 42mm undermount slide deduction to 1-5/8" (41.28mm) instead of 1-21/32" (42.07mm) | 0.8mm discrepancy causes drawer side to bind against metal runner flange | Always use exact millimeter measurements when installing European Blum or Salice hardware |
Frequently Asked Engineering Questions
High-intent technical fabrication inquiries verified against lab standards.
Q1What is 1/8 inch converted to decimal and millimeters?
Q2How do you find the closest 64th fraction from digital caliper decimals?
Q3Why does European cabinet hardware use 32mm hole spacing?
Q4What is the metric equivalent of 3/4 inch cabinet plywood?
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