The tap drill for M12 x 1.75 is 10.2 mm (0.4016 in), which gives about 79% of full thread depth. The exact 75% hole is 0.4053 in (10.30 mm). The table lists every number, letter, fractional and metric drill that gives between 55% and 90% thread, so you can work from the bits you own.
| Drill | Type | in | mm | Thread | Note |
|---|---|---|---|---|---|
| X | letter | 0.3970 | 10.08 | 84% | deep, hard to tap |
| 10.1 mm | metric | 0.3976 | 10.10 | 84% | deep, hard to tap |
| 10.2 mm | metric | 0.4016 | 10.20 | 79% | chart drill |
| Y | letter | 0.4040 | 10.26 | 76% | |
| 10.3 mm | metric | 0.4055 | 10.30 | 75% | |
| 13/32" | fraction | 0.4062 | 10.32 | 74% | |
| 10.4 mm | metric | 0.4094 | 10.40 | 70% | |
| Z | letter | 0.4130 | 10.49 | 66% | easier to tap |
| 10.5 mm | metric | 0.4134 | 10.50 | 66% | easier to tap |
| 27/64" | fraction | 0.4219 | 10.72 | 56% | easier to tap |
About the M12 x 1.75 thread
M12 x 1.75 is the coarse 12 mm thread used for heavy machinery, structural connections, anchor bolts and large brackets. Fine M12 threads are best known as wheel stud and lug nut threads: many cars use M12 x 1.5 and some use M12 x 1.25. If you are matching wheel hardware, read the maker’s data rather than measuring, because the two fine pitches are easy to mistake for each other.
Diameter minus pitch gives 10.25 mm for the coarse thread, and 10.2 mm is the standard bit. The fine rows below give 10.5 mm for M12 x 1.5 and 10.75 mm for M12 x 1.25 (a 10.8 mm bit).
M12 x 1.75 thread dimensions
| Dimension | Value | Also |
|---|---|---|
| Nominal diameter | 12 mm | 0.4724 in |
| Pitch | 1.75 mm | 14.51 threads per inch equivalent |
| Basic pitch diameter | 10.863 mm | 0.4277 in |
| Basic minor diameter (nut) | 10.106 mm | 0.3979 in |
| Tensile stress area | 84.27 mm² | 0.1306 in² |
| Fine thread M12 x 1.5: tap drill | 10.50 mm | 77% thread |
| Fine thread M12 x 1.25: tap drill | 10.75 mm | 77% thread |
Clearance hole for M12
The tapped hole is in the part that holds the thread; the part being clamped gets a clearance hole the bolt passes through. For M12 a normal fit is 13.5 mm. Never drill the clearance part with the tap drill: the screw will not pass.
| Fit | Drill | Diameter |
|---|---|---|
| Close (ISO 273 fine) | 13 mm | 0.5118 in |
| Normal (ISO 273 medium) | 13.5 mm | 0.5315 in |
| Loose (ISO 273 coarse) | 14.5 mm | 0.5709 in |
How deep to drill a blind M12 x 1.75 hole
| Part material | Full thread wanted | Drill depth (full diameter) | Depth to drill tip (118°) |
|---|---|---|---|
| Steel or cast iron (1 × diameter) | 12.0 mm | 24.2 mm | 27.3 mm |
| Aluminium or brass (2 × diameter) | 24.0 mm | 36.2 mm | 39.3 mm |
Wrench size and torque for M12
- Hex bolt or nut: 18 mm wrench (ISO), 19 mm on DIN 933 and older bolts
- Socket head cap screw (ISO 4762): 10 mm hex key
| Bolt grade | Dry | Lubricated |
|---|---|---|
| Class 8.8 | 88.0 N·m (64.9 ft-lb) | 66.0 N·m |
| Class 10.9 | 125.9 N·m (92.9 ft-lb) | 94.4 N·m |
| Class 12.9 | 147.1 N·m (108.5 ft-lb) | 110.3 N·m |
Threads easily mistaken for M12 x 1.75
| Thread | Diameter (in) | Diameter (mm) | Pitch |
|---|---|---|---|
| M12 x 1.75 (this page) | 0.4724 | 12.00 | 1.75 mm (14.5 TPI) |
| M12 x 1.5 | 0.4724 | 12.00 | 1.5 mm (16.9 TPI) |
| M12 x 1.25 | 0.4724 | 12.00 | 1.25 mm (20.3 TPI) |
| 1/2-13 UNC | 0.5000 | 12.70 | 13 TPI (1.95 mm) |
| 1/2-20 UNF | 0.5000 | 12.70 | 20 TPI (1.27 mm) |
Tips for tapping M12 x 1.75
- Wheel studs and lug nuts are safety parts: replace damaged ones; do not re-tap them.
- An M12 hex bolt needs an 18 mm wrench (ISO 4014) or 19 mm (DIN 933); an M12 socket head cap screw takes a 10 mm hex key.
- At 10.2 mm the tap cuts a lot of metal: use a step drill or pilot first, and break the chip often.
- M12 and 1/2-13 are close (0.472 vs 0.500 in) but not interchangeable.
Frequently asked questions
What size drill bit for an M12 x 1.75 tap?
10.2 mm, which gives about 79% thread. The exact 75% size is 0.4053 in (10.30 mm).
How deep should a blind M12 x 1.75 hole be?
For a full thread of 1 × diameter in steel, drill about 24.2 mm at full diameter with a plug tap, or 27.3 mm to the drill tip; in aluminium, about 36.2 mm.
What size drill for M12 x 1.5?
10.5 mm (12 minus 1.5).
What size drill for an M12 tap in inches?
13/32 in (0.406 in, 10.32 mm) is the nearest fraction to 10.2 mm, and letter Y (0.404 in) is closer still.
Sources and method
Every dimension and percentage on this page is computed from the formulas listed, not copied from another chart. Values are basic (nominal); real parts are made to tolerance classes (2A/2B for inch, 6g/6H for metric).
- ASME B1.1 and FED-STD-H28/2B (Unified inch), ISO 68-1 and ISO 261 (metric): basic thread profile and stress area formulas.
- Machinery’s Handbook (Industrial Press): percentage-of-thread relation used by our tap drill size calculator.
- ASME B94.11M twist drill series (number, letter, fractional); 0.1 mm metric drill steps.
- ISO 273 metric clearance holes; inch close, normal and loose fits as published in the ASME B18.2.8 clearance classes.
- SAE J429 and ISO 898-1 proof strengths; T = K × D × F torque relation (see our bolt torque chart for the full method).
- Wrench and hex key sizes: ASME B18.2.1, ASME B18.3, ASME B18.6.3, ISO 4014/4017, DIN 933 and ISO 4762 values as widely published.
More thread and fastener tools
- All thread and fastener charts
- UNC and UNF thread chart
- Metric thread pitch chart
- Tap drill chart (inch and metric)
- Clearance hole chart
- Nail size chart
- Wood screw size chart
- Lag screw pilot hole chart
- Bolt torque chart
- Wrench size chart
- Drill bit size chart
- Thread engagement chart
- Nail gun nail sizes by gauge
- Screw and nail size calculator
- Tap drill size calculator
- Clearance hole size calculator
- Tapped hole depth calculator
Last reviewed: 24 October 2026. How we build and check our data: methodology and corrections. Spotted an error? Please let us know.